THE STATE OF WESTERN AUSTRALIA -v- MOUSSA [2026] WASC 164

[2026] WASC 164 Page 1 JURISDICTION : SUPREME COURT OF WESTERN AUSTRALIA IN CRIMINAL CITATION : THE STATE OF WESTERN AUSTRALIA -v- MOUSSA [No 2] [2026] WASC 164 CORAM : PALMER J HEARD : 28 APRIL 2026 DELIVERED : 1 MAY 2026 FILE NO/S : INS 24 of 2025 BETWEEN : THE STATE OF WESTERN AUSTRALIA Prosecution AND DAVID NADI LAMIE MOUSSA Accused Catchwords: Criminal law - Trial by judge alone - Murder - Where the accused admitted to killing the deceased - Whether the accused was mentally impaired - Whether the accused was deprived of any of the capacities specified in s 27 of the Criminal Code Legislation: Criminal Law (Mental Impairment Act 2023 (WA) Criminal Code (WA) Criminal Procedure Act 2004 (WA) Evidence Act 1906 (WA) -- 1 of 41 -- [2026] WASC 164 Page 2 Result: Not guilty on account of mental impairment pursuant to s 27(1) of the Criminal Code Category: B Representation: Counsel: Prosecution : Ms K Jennings Accused : Ms A Fedele Solicitors: Prosecution : Director of Public Prosecutions (WA) Accused : Legal Aid (WA) Case(s) referred to in decision(s): Evans v The State of Western Australia [2010] WASCA 34 Hone v The State of Western Australia [2007] WASCA 283; (2007) 179 A Crim R 138 R v Falconer [1990] HCA 49; (1990) 171 CLR 30 R v Porter [1933] HCA 1; (1933) 55 CLR 182 Stapleton v The Queen [1952] HCA 56; (1952) 86 CLR 358 State of Western Australia v Dent (No 2) [2023] WASC 261 State of Western Australia v Zahidi [No 2] [2024] WASC 8 The State of Western Australia v Jones [2018] WASC 395 The State of Western Australia v McCullock [No 2] [2024] WASC 400 The State of Western Australia v Taylor [2021] WASC 470 -- 2 of 41 -- [2026] WASC 164 PALMER J Page 3 PALMER J: Introduction 1 The accused, Mr David Nadi Lamie Moussa, stands trial for the murder of his father Mr Nadi Moussa and for an omission causing danger to his stepmother, Ms Theresa Awad Soliman Salama (arising out of his control of a knife). 2 Without intending any disrespect, as these reasons refer to various members of the Moussa family, I will refer to them by their first names. 3 In late 2025, David was living in Brisbane. He was enrolled as a medical student at the University of Queensland. He had been struggling at university and his mental health started to deteriorate. By January 2025, he became mentally ill and was experiencing psychosis and delusions. 4 David began to have delusions that he was part of a secret government research project, that he had been abused by his father throughout his life, and that his father was trying to kill him. David had difficulty distinguishing between delusion and reality. 5 On 13 January 2025, David was seen by a psychiatrist in Brisbane who assessed him as being psychotic and who prescribed him anti-psychotic medication. Although David took that medication, anti-psychotic medication takes time to be effective. Despite taking the medication, he began experiencing homicidal thoughts. 6 On or about 27 January 2025, David decided that he had no choice but to kill his father. In his psychotic and deluded state, he believed that the 'researchers' had told him to kill his father to bring the 'research project' to an end. He set out to drive from Brisbane to Perth. He brought a kitchen knife with him, intending to use it to attack his father. 7 When he arrived at his father's house in suburban Perth on 27 January 2025, there was no one there. His father, his stepmother Theresa, and Angela (his 6-year-old half-sister) were away on holiday. David decided to wait for them to come home and waited for them at their house. 8 On 4 February 2025, they returned home. Shortly afterwards, David confronted his father in the kitchen with the knife he had brought with him. There was a struggle during which Theresa and Nadi were -- 3 of 41 -- [2026] WASC 164 PALMER J Page 4 injured. Nadi opened the front door and took refuge behind his car parked outside the front of his house. David found him there and stabbed him repeatedly. Theresa tried to intervene and she was stabbed too. Nadi died from the stab wounds he sustained during the attack. 9 At one point during the attack, David told his father that he was sorry. I have no doubt that he is sorry, and that he and his entire family will be haunted by the tragic events of that day for the rest of their lives. 10 What happened was not the subject of any real dispute at trial. David admitted the facts set out in an agreed statement of facts, pursuant to s 32 of the Evidence Act 1906 (WA).1 On the basis of those admissions, I am satisfied beyond reasonable doubt that David unlawfully killed Nadi and that he omitted to do an act that it was his duty to do, endangering the life, health and safety of Theresa. 11 The substantive issue at trial was whether David could prove, on the balance of probabilities, that he was not criminally responsible for these offences on account of mental impairment. Whether David was criminally responsible turns on two matters: (a) first, whether David was mentally impaired at the time that he committed the offences; and (b) secondly, if so, was it more likely than not that his mental impairment deprived him of one of the capacities contained in s 27(1) of the Criminal Code (WA) (Criminal Code). 12 The defence called a consultant psychiatrist, Dr Adam Brett, to give evidence. He interviewed David, reviewed materials that were provided to him, and prepared four written reports. He also gave oral evidence at trial. 13 Dr Brett considered that David suffered from a mental illness in the schizophrenia spectrum at the time he committed the offences. Dr Brett thought that David's mental impairment deprived him of the capacity to know that he ought not kill his father. Dr Brett’s opinion was that David's mental impairment meant that he lacked the capacity to safely and properly control the knife the subject of the charge concerning Theresa. 1 See Exhibits 1 and 2. -- 4 of 41 -- [2026] WASC 164 PALMER J Page 5 14 The prosecution did not call an expert psychiatrist to give evidence and did not seek to dispute Dr Brett's evidence. In closing, the prosecutor submitted that given Dr Brett's evidence, it was open to the court to be satisfied that David had establish the matters necessary to make out an insanity defence. 15 I accept Dr Brett's evidence. He gave cogent and compelling evidence that was uncontradicted. On the basis of that evidence, I am satisfied on the balance of probabilities that David was suffering from a mental illness in the schizophrenia spectrum and that his mental impairment deprived him of the capacity to know that he ought not kill his father and the capacity to safely and properly control the knife the subject of the charge concerning Theresa. I find David not guilty of both counts on account of mental impairment. 16 My verdict does not mean that David will now be released into the community. Given my verdict, the Criminal Law (Mental Impairment) Act 2023 (WA) (the CLMI Act) requires me to make an order in relation to David under pt 5 of that Act. 17 As the offence of murder is a serious offence, I must make a custody order unless I am satisfied, on the balance of probabilities, that any risk that he appears to present to the safety of the community can be adequately managed under a community supervision order. 18 The appropriate order to be made under the CLMI Act will not be determined today. The defence has requested that reports be obtained to assist the consideration of the appropriate order to be made. I will order those reports be obtained. The appropriate order to make under pt 5 of the CLMI Act will be determined at a later date, after those reports are available. 19 I set out my reasons for these conclusions, including the principles of law that I have applied, and the findings of fact upon which I have relied below. The principles of law that I have applied 20 Section 119(1) of the Criminal Procedure Act 2004 (WA) (Criminal Procedure Act) requires me, as a judge sitting alone, to apply so far as practicable, the same principles of law and procedure as would be applied in a trial before a jury. -- 5 of 41 -- [2026] WASC 164 PALMER J Page 6 21 Section 120(2) of the Criminal Procedure Act requires me to state the principles of law that I have applied and the findings of fact upon which I have relied. General principles applicable to criminal trials 22 I have applied the following general principles of law that apply in criminal trials. Burden and standard of proof 23 David is presumed to be innocent of the charge. 24 The burden of proving his guilt is on the State. The standard of proof required to be achieved is proof beyond reasonable doubt. Unless I am satisfied that each element of each offence has been proved to that standard, David must be acquitted. Multiple charges 25 There are two separate charges on the indictment. Each charge could have been the subject of a separate trial before a different judge. However, separate trials have not been held because it would not be fair to David or the State for the evidence to be taken on two separate occasions. 26 Although the charges have been heard together it is important for me to remember at all times that there are two separate charges. I must deal with each charge separately and make a decision on each charge separately. When I am dealing with each charge I must consider only the evidence that is relevant to the charge. 27 I must not allow a verdict that I arrive at on one of the charges to lead me automatically to the same verdict on the other charge. My verdicts do not have to be the same on each charge. 28 I must not draw any inference against the accused or make any conclusions against him or be prejudiced against him because there is more than one charge. The State has decided to charge the accused with two offences. My duty in respect of each charge is to consider the evidence relevant to that charge and on the basis of that evidence arrive at my verdict. -- 6 of 41 -- [2026] WASC 164 PALMER J Page 7 Prejudice and sympathy 29 In assessing the evidence and reaching a verdict, it is necessary to guard against any feelings of prejudice or sympathy. Such feelings must be put aside, and the issue of whether David's guilt has been proved must be determined dispassionately and objectively. Speculation and inferences 30 I must not speculate about matters not in evidence or look for theories that are not supported by the evidence. My verdict must be based only on the evidence. 31 If it is necessary to draw inferences as to essential facts from the evidence, I am not permitted to draw an inference adverse to David unless that inference is the only reasonable one open on the evidence. 32 I direct myself that it is dangerous to assess David's words and actions in testing his capacity to control his actions or to know that he ought not to do the act that resulted in the charge by the standards of people who do not suffer from a mental illness. Accused giving evidence 33 David did not give evidence. It was his right not to do so and no inference adverse to him can be drawn by reason of the fact that he chose not to give evidence. The law regarding murder 34 Pursuant to s 279 of the Criminal Code, the elements of the offence of murder are: (1) that David killed Nadi; (2) the killing was unlawful; and (3) at the time David killed Nadi, he intended to cause Nadi's death or intended to cause him a bodily injury of such a nature as to endanger, or be likely to endanger, his life. 35 In relation to the first element, a person who causes the death of another, either directly or indirectly, is deemed to have killed that other person.2 2 Criminal Code s 270. -- 7 of 41 -- [2026] WASC 164 PALMER J Page 8 36 Whether a killing constitutes the offence of murder depends upon the intention of David at the relevant time. 37 David has raised the defence of insanity. In circumstances where that defence has been raised it is necessary to consider whether David is criminally responsible for the killing, having regard to s 27 of the Criminal Code. The law regarding an act or omission causing bodily harm or danger 38 Given that identity if not in issue,3 the elements of the offence of an act or omission causing bodily harm or danger contrary to s 304(1) of the Criminal Code are: (a) that David omitted to do an act it was his duty to do; (b) the act was David's duty to do; (c) the omission caused, or was likely to cause, the life, health or safety of Theresa to be endangered; and (d) the act was unlawful in that it was not authorised, justified or excused by law. 39 Again, as David has raised the defence of insanity, it is necessary to consider whether David is criminally responsible for the act or omission, having regard to s 27 of the Criminal Code. The law regarding insanity Section 27 of the Criminal Code 40 Section 27 of the Criminal Code is applicable in this trial. David's defence is that at the time he committed the offences he was psychotic and delusional and he suffered from a mental illness in the schizophrenia spectrum. 41 Every person is presumed to be of sound mind until the contrary is proved.4 David has the onus of proving, on the balance of probabilities, that he was not of sound mind, that is he is not criminally responsible pursuant to s 27 of the Criminal Code at the time that he did the acts that are alleged to constitute the offences.5 3 I am satisfied that David was the offender beyond reasonable doubt in any event. 4 Criminal Code s 26. 5 R v Porter [1933] HCA 1; (1933) 55 CLR 182. -- 8 of 41 -- [2026] WASC 164 PALMER J Page 9 42 Section 27 of the Criminal Code provides as follows: Insanity (1) A person is not criminally responsible for an act or omission on account of mental impairment if at the time of doing the act or making the omission he is in such a state of mental impairment as to deprive him of the capacity to understand what he is doing, or of capacity to control his actions, or of capacity to know that he ought not to do the act or make the omission. (2) A person whose mind, at the time of his doing or omitting to do an act, is affected by delusions on some specific matter or matters, but who is not otherwise entitled to the benefit of subsection (1), is criminally responsible for the act or omission to the same extent as if the real state of things had been such as he was induced by the delusions to believe to exist. 43 Section 1(1) of the Criminal Code defines 'mental impairment' to mean intellectual disability, mental illness, brain damage or senility. The term 'mental illness' is defined as meaning: An underlying pathological infirmity of the mind, whether of short or long duration, and whether permanent or temporary, but does not include a condition that results from the reaction of a healthy mind to extraordinary stimuli. 44 The question of what constitutes mental illness is a question of law, and the question of whether or not the facts disclose a state of mental illness is a question of fact.6 45 In The State of Western Australia v Jones,7 Jenkins J made the following observations regarding the definition of 'mental illness', with which I respectfully agree and adopt: The definition of 'mental illness' reflects some of the comments made by King CJ in Radford about the meaning of the expression 'disease of the mind' which is used in the common law of insanity. Summarising the statement of King CJ: 1 'Disease of the mind' is synonymous with 'mental illness'; 2 A temporary disorder or disturbance of an otherwise healthy mind caused by external factors is not properly regarded as a disease of the mind; 6 R v Falconer [1990] HCA 49; (1990) 171 CLR 30, 60. 7 The State of Western Australia v Jones [2018] WASC 395 [43]. -- 9 of 41 -- [2026] WASC 164 PALMER J Page 10 3 Major mental illness or psychoses such as schizophrenia are clearly diseases of the mind as are physical diseases, such as psychomotor epilepsy and arteriosclerosis, when they affect the soundness of the mental faculties; 4 Disease of the mind is to be distinguished from 'mere excitability of a normal man, passion, even stupidity, obtuseness, lack of self-control and impulsiveness'; and 5 In order to constitute insanity in the eyes of the law the malfunction of the mental faculties 'must result from an underlying pathological infirmity of the mind, be it of long or short duration and be it permanent or temporary, properly be termed mental illness, as distinct from the reaction of a healthy mind to extraordinary external stimuli'. (footnotes omitted) Capacity to control actions 46 The phrase 'capacity to control' as used in s 27(1) has its ordinary plain meaning. The ordinary plain meaning of the word 'capacity' given the context in which it is being used in s 27(1), is 'a mental power; a faculty'. The ordinary plain meaning of the word 'control' is 'the power of restraining especially self-restraint'.8 47 The meaning of 'capacity to control' was considered by Derrick J in Taylor, who summarised the position as follows:9 There is, in my view, no justification for failing to give the phrase 'capacity to control' as used in s 27(1) its ordinary plain meaning. The ordinary plain meaning of the word 'capacity' given the context in which it is being used in s 27(1), is 'a mental power; a faculty'. The ordinary plain meaning of the word 'control' is 'the power of restraining especially self-restraint'. In my opinion the ordinary plain meaning of the words 'capacity to control' used in s 27(1) and a review of the relevant authorities supports the conclusion that a person is deprived of the capacity to control their actions within the meaning of the section if they are deprived of the capacity to make a conscious decision to act (that is, to act voluntarily) or if they are deprived of the capacity to refrain or restrain themselves from doing a willed act (sometimes also referred to as the capacity to exercise the power of choice to act). Thus, in my opinion, if the effect of a person's mental impairment is to deprive them of the capacity to refrain from doing an act, that is, to exercise the power of choice to act, they will, by reason of their mental impairment, be deprived of the capacity to control their actions within 8 The State of Western Australia v Taylor [2021] WASC 470 [50] (Taylor). 9 Taylor, [50] and [52]. See also: State of Western Australia v Dent (No 2) [2023] WASC 261 [31] and State of Western Australia v Zahidi [No 2] [2024] WASC 8 [28]. -- 10 of 41 -- [2026] WASC 164 PALMER J Page 11 the meaning of s 27(1) even though the act was a willed or deliberate act; an act done as a result of a consciously made decision. It necessarily follows that in determining the effect of a person's mental impairment on their capacity to control their actions the focus will often be on the extent to which their delusions or hallucinations (if any) controlled their actions or deprived them of the power of choice. … Nothing I have said should be taken as indicating that a person will be deprived of the capacity to control their actions merely by reason of them having a significantly impaired capacity to resist an impulse or an emotion. A significantly impaired capacity to resist an impulse or an emotion does not equate to a deprivation of a person's capacity to control their actions within the meaning of s 27(1). (footnotes omitted) 48 I respectfully agree with and adopt Derrick J's approach. Capacity to know ought not do the act 49 The meaning of the phrase the capacity to know that he ought not to do the act or make the omission was considered by the High Court in Stapleton v The Queen:10 A case of this description must turn very largely upon the jury's appreciation of what amounts to knowledge of the nature and quality of the act and of its wrongness. For it is evident that a jury although satisfied that no capacity existed in a particular accused to reason at all may think that at the back of it all was an awareness of the nature of the act and of the fact that other people might regard it as wrong more especially if that means regarded by the law as wrong. That would not lead to a conviction if the jury understands that, given a disease disorder or defect of reason, then it is enough if it so governed the faculties at the time of the commission of the act that the accused was incapable of reasoning with some moderate degree of calmness as to the wrongness of the act or of comprehending the nature or significance of the act of killing. See R v Davis (1881) 14 Cox CC 563, Stephen J, R v Kay (1904) 68 JP Jo 376, Stephen J. In R v Porter (1933) 55 CLR 182 at pp 189, 190, this was expressed by Dixon J as follows: 'The question is whether he was able to appreciate the wrongness of the particular act he was doing at the particular time. Could this man be said to know in this sense whether his act was wrong if through a disease or defect or disorder of the mind he could not think rationally of the reasons which to ordinary people make that act right or wrong? If through the 10 Stapleton v The Queen [1952] HCA 56; (1952) 86 CLR 358, 367 (Stapleton). -- 11 of 41 -- [2026] WASC 164 PALMER J Page 12 disordered condition of the mind he could not reason about the matter with a moderate degree of sense and composure it may be said that he could not know that what he was doing was wrong. (footnotes omitted) 50 The High Court also held that a direction to a jury that 'wrong' meant 'against the law' was in error. There is no requirement that an accused know the act is wrong in the sense of being contrary to law, but that rather it is a question of knowing right from wrong, good from evil, not legality from illegality.11 The High Court went on to observe that in some cases this distinction may not be of much significance, but in others it may be.12 51 In Evans v The State of Western Australia,13 the Court of Appeal considered the application of the common law principles to s 27 of the Criminal Code. President McLure stated that there was no suggestion that there was any material distinction between the common law test as stated by the High Court in Stapleton v The Queen and s 27 of the Criminal Code. President McLure went on to consider the term 'know' in s 27 of the Criminal Code and concluded:14 Thus the real issue for the jury in this case was whether the appellant had established on the balance of probabilities that at the time of the killing his mental impairment resulted in a complete incapacity to reason as to what is right or wrong according to ordinary standards. The term 'know' means 'understand', 'appreciate' or 'comprehend'. An incapacity to reason rationally as to what is right or wrong according to ordinary standards prevents a person from understanding that he (or she) ought not do the act. Knowledge (short of understanding) that to kill is punishable by law does not prevent such a finding. Nor is a finding of incapacity dependent upon proof of a positive belief in the rightness of the conduct. Whether an act is right or wrong is determined by reference to an objective standard. The question is whether the appellant had a complete incapacity to reason as to what was, by that objective standard, right or wrong. 52 Justice of Appeal Wheeler (with whom Owen JA agreed) held as follows:15 It is not easy to summarise the detailed discussion of authority in Stapleton in a way which is capable of being fashioned into an 11 Stapleton, 367 - 368. 12 Stapleton, 370 - 371. 13 Evans v The State of Western Australia [2010] WASCA 34 (Evans). 14 Evans [31]. 15 Evans [60]. -- 12 of 41 -- [2026] WASC 164 PALMER J Page 13 appropriate direction in every case of insanity. However, the principles extracted from that discussion appear to focus upon two issues. First, the ability to know that one 'ought not' to do an act or make an omission is a capacity to know that one 'ought not' to do it according to ordinary standards of right and wrong, rather than knowledge that the act is unlawful. As the High Court observed, from a practical point of view it often may not matter much, because in relation to serious offences the two ideas 'are not easily separable' (at 375). However, in cases where, as here, the distinction may arise, it should be made. The second principle is that the capacity which must be found to be lacking is not merely a capacity to appreciate, in some abstract sense, that others would view the act as wrong. Rather, it is a capacity of the particular accused either to discern the difference between moral good and evil, or to 'think rationally' of the reasons which would lead ordinary people to consider the act to be right or wrong. The law regarding expert psychiatric opinion of insanity 53 In Hone v The State of Western Australia, the Court of Appeal considered the significance of uncontradicted expert psychiatric opinion evidence where the issue of insanity is raised by an accused. In that case Miller JA said the following:16 Neither a jury nor a judge sitting alone are bound to accept and act upon expert evidence. But where there is no evidence to contradict that evidence, a verdict cannot be given contrary to it. The principles were well summed up by Roden J in Hall (1988) 36 A Crim R 368, where a number of relevant cases were reviewed. Roden J said: 'Juries are not bound to accept and act upon expert evidence. Nevertheless they are not entitled to disregard it capriciously. These two propositions have found expression and support in a line of authorities developed in England with regard to the defences of insanity and diminished responsibility. In Rivett (1950) 34 Cr App R 87, Lord Goddard CJ, said (at 94): 'The second matter for emphasis is that it is for the jury and not for medical men of whatever eminence to determine the issue. Unless and until Parliament ordains that this question is to be determined by a panel of medical men, it is to a jury, after a proper direction by a judge, that by the law of this country the decision is to be entrusted.' The Court of Criminal Appeal was there dealing with medical evidence relating to a defence of insanity. 16 Hone v The State of Western Australia [2007] WASCA 283; (2007) 179 A Crim R 138 [124] - [125]. See also the comments made by Steytler P at [6], [13]. -- 13 of 41 -- [2026] WASC 164 PALMER J Page 14 Eight years later, when dealing with a defence of diminished responsibility, Lord Goddard showed the other side of the coin, in Matheson [1958] 1 WLR 474; 42 Cr App R 145, saying (at 478; 151): 'While it has often been emphasised, and we would repeat that the decision in these cases, as in those in which insanity is pleaded, is for the jury and not for doctors, the verdict must be founded on evidence. If there are facts which would entitle a jury to reject or differ from the opinions of the medical men, this court would not, and indeed could not, disturb their verdict, but if the doctors' evidence is unchallenged and there is no other on this issue, a verdict contrary to their opinion would not be 'a true verdict in accordance with the evidence'.' In Bailey (1977) 66 Cr App R 31, another diminished responsibility case, Lord Parker CJ said (at 32): 'The court has said on many occasions that of course juries are not bound by what the medical witnesses say, but at the same time they must act on evidence, and if there is nothing before them, no facts and no circumstances shown before them which throw doubt on the medical evidence, then that is all that they are left with, and the jury, in those circumstances, must accept it.' In both Matheson and Bailey, manslaughter verdicts were substituted for jury verdicts of guilty of murder, on the basis that the medical evidence was 'all one way', and there was no other material which would justify its rejection. It was otherwise in Walton [1978] AC 788; 66 Cr App R 25. The Privy Council was there considering a murder conviction where a diminished responsibility defence had been rejected. In the judgment, which was delivered by Lord Keith of Kinkel, there are observations that 'the jury were entitled to regard (the medical evidence) as not entirely convincing', and 'their Lordships have come to be of opinion that in all the circumstances the jury were entitled not to accept as conclusive the expression of opinion by Dr Bannister'. After a consideration of both Matheson and Bailey, the following statement of principle was made: 'These cases make clear that upon an issue of diminished responsibility the jury are entitled and indeed bound to consider not only the medical evidence but the evidence upon the whole facts and circumstances of the case. These include the nature of the killing, the conduct of the defendant before, at the time of and after it and any history of mental abnormality. It being recognised that the jury on occasion may properly refuse to accept medical evidence, it follows that they must be entitled to consider the quality and weight of that evidence.' -- 14 of 41 -- [2026] WASC 164 PALMER J Page 15 The effect of those decisions is accurately summarised in Professor Smith's commentary on Walton in (1977) Crim LR 747 at 748: 'If the medical evidence is all one way and in favour of the accused and there is nothing in the facts and surrounding circumstances which could lead to a contrary conclusion, then a verdict against the medical evidence cannot be sustained. In the present case there were facts and circumstances in addition to the medical evidence and the jury was therefore entitled to reject that evidence.' (370 - 371)' Allen J summarised the position as follows: There is no rule of law that a verdict of guilty will be quashed as unsafe in any case in which the verdict is inconsistent with medical evidence called for the accused - even where no medical evidence has been called for the Crown. On the other hand there is no rule of law that an appellate court will not quash such a verdict - refusing to do so because it is open to a jury to reject the opinion of any expert witness. Each case is unique. The totality of the evidence must be weighed: Walton [1978] AC 788; 66 Cr App R 25. In assessing medical evidence a multitude of factors must be taken into account - including the standing of the expert, whether he expresses his opinion with conviction or with hedging, whether the opinion expressed in its nature seems reasonable or fanciful, whether it incorporates assumptions not founded upon the evidence given, and whether the evidence given, upon which the opinion is based, is to be believed. It is clearly settled that it can be unreasonable for a jury to reject medical testimony: Walton; Chester [1982] Qd R 252; 5 A Crim R 296. (380 - 381)'. 54 Therefore, although neither a jury nor a judge sitting alone is bound to accept and act upon expert opinion evidence, if there is no evidence, fact or circumstance that contradicts the evidence or warrants a conclusion that the evidence is unreliable, a verdict cannot be given that is contrary to the evidence. Expert evidence cannot be disregarded capriciously.17 The findings of fact upon which I have relied 55 As I have said, the relevant facts were not in issue at trial. I make the findings of fact in paragraphs 56 to 136 below, based on the agreed statement of facts. 17 Taylor [73]. -- 15 of 41 -- [2026] WASC 164 PALMER J Page 16 David's history of health problems 56 David has a history of long term health problems. He has been diagnosed with Crohn's disease and cystitis glandularis.18 David's undergraduate and post-graduate degrees 57 David holds a number of undergraduate and post-graduate degrees. He completed a Bachelor of Science (Biomedical Science). He also completed two masters degrees: a Masters in Psychological Sciences and a Masters in Medical Statistics.19 2023: David enrols in medicine but struggles 58 In 2023, David enrolled in medicine at the University of Queensland.20 59 As the year progressed, however, he started to fall behind in his studies.21 60 David sought help from a counsellor at the University of Queensland and a doctor at the university. He was referred to a psychologist at the university but given the length of the waiting list, he saw a private psychiatrist.22 61 In May 2023 he was prescribed ADHD medication which helped with his studies, but he was subsequently advised that he had lost his place in medical school. He successfully appealed that decision, however.23 2024: David continues to struggle at university 62 On 31 August 2024, David presented to the Princess Alexandra Hospital Emergency Department with abdominal, pelvic and perineal pain (he had recently had a colonoscopy). 24 63 David was given paracetamol and told to follow-up with a gastroenterologist. He was discharged on 1 September 2024 with a diagnosis of a viral illness with secondary abdominal pain. 25 18 Exhibit 1 [4]. 19 Exhibit 1 [4]. 20 Exhibit 1 [5]. 21 Exhibit 1 [5]. 22 Exhibit 1 [5]. 23 Exhibit 1 [5]. 24 Exhibit 1 [6]. -- 16 of 41 -- [2026] WASC 164 PALMER J Page 17 64 Around examination time that year, David was not physically well and did not perform well in that round of exams.26 65 Throughout 2024, David continued to struggle at university. On November 2024, he received notification that he had received a 'N' grade on his BE component.27 David experiences a psychotic episode in Brisbane 66 In early January 2025, David sent messages to a childhood friend in which he discussed accessing his 'child welfare records', that his records had been deleted, and that he was trying to get in contact with a 'children's welfare researcher'.28 67 He sent messages like: (a) 'They can't find anything because it's all been deleted'; (b) 'I have a million witnesses'; (c) 'I dunno how they think they can get away with this'; (d) 'it's all stuff my family admitted to'; and (e) 'they had to admit everything as part of the deal'. 29 68 On 13 January 2025, Dr Damon Batts, David's psychiatrist in Brisbane, prepared a report concerning a consultation he had with David in which: (a) Dr Batts recorded David: (i) having increasing dreams over several months of negative childhood memories of significant abuse and neglect; (ii) believing that his mother was not dead and that his family put on a sham funeral; (b) Dr Batts observed that there were multiple stressors in David's life at the time including his relationship ending, failing a rental 25 Exhibit 1 [6]. 26 Exhibit 1 [6]. 27 Exhibit 1 [7]. 28 Exhibit 1 [8]. 29 Exhibit 1 [8]. -- 17 of 41 -- [2026] WASC 164 PALMER J Page 18 inspection, and being told that he may not be able to progress in his medical degree; (c) Dr Batts thought that David presented with likely psychotic symptoms in the context of dexamphetamine use and psychological stressors, ADHD combined presentation and Crohn's disease and cystic glandularis; (d) Dr Batts thought that David was 'not completely insightless' and was willing to try treatment; and (e) David was referred to a psychologist for a mental health plan.30 69 On 15 January 2025, when David filled out a new client intake form for Anxiety House in Brisbane, he ticked the box 'yes' when asked if he had ever had any homicidal thoughts.31 70 The same day David sent numerous messages to his friend saying things like: (a) 'so first, I ditch the drugs'; (b) 'I need to find out how much of what I think is true is actually so'; (c) 'new plan, no drugs except for antipsychotics'; (d) 'I guess I got a bit too freaked out by the memories and haven't slept in a while'; (e) 'I've decided to go home. Told them to get fucked in a message I typed into Google search'; (f) 'Dude the shit they are sending me lol. All through different mediums. Text. Email, random flashes on screen'; (g) 'Bigger fish to fry. Sending my father to prison!'; (h) 'Fuck this I'm going to sleep. Must be lack of sleep. Plus researcher is fucking with me'; and (i) 'Soon I will be dead'. 30 Exhibit 1 [9]. 31 Exhibit 1 [10]. -- 18 of 41 -- [2026] WASC 164 PALMER J Page 19 71 David's messages also mentioned a 'worker' putting drugs in his slushy. He also comments about ditching all the drugs and first dinging [sic] out how much of what he thinks is true is actually so. 32 72 On 16 January 2025, David saw a clinical psychologist for an initial appointment. In the psychiatric assessment form, David indicated that the 'dreams' (of family abuse, neglect etc by his father) started vividly from 5 - 17 December 2024. He stated that he felt they were memories and not dreams.33 73 The same day, David sent more messages to his friend saying things like: (a) 'You wouldn't be pushing this so hard unless you were in on it. Dr Batts is a shit actor. His script was also stupid. Asking me about shit that I never even told him. I last saw him in late July. I did...'; (b) 'Due, wtf the text I send. Just ignore. I'm fine, Just need sleep more'; and (c) 'I can't believe I actually went insane for a moment'.34 74 On the same day, David sent a message to another friend saying 'I'm pretty sure I'm being followed everywhere by reptilians'.35 75 On 18 January 2025, David sent messages to his friend saying 'Let's say you have been abused the shit out of your entire life. By your own family and 'friends…And the State was in on it the entire time. Then they magically can't find any paperwork. Oopsie'[sic]. 36 76 A case note prepared by a clinical psychologist at Anxiety House on 20 January 2025 records that: (a) David was deliberately not contacting family in case he 'kills them'; (b) the psychologist thought that David was experiencing 'likely first episode psychosis'; and 32 Exhibit 1 [11]. 33 Exhibit 1 [12]. 34 Exhibit 1 [12]. 35 Exhibit 1 [12]. 36 Exhibit 1 [13]. -- 19 of 41 -- [2026] WASC 164 PALMER J Page 20 (c) David was experiencing 'transient homicidal ideation. Denies any plan or intent to harm any member of family or other. Denies any plan or intent to travel to Perth to see family. States will follow legal course'.37 77 On 21 January 2025, David had a telephone consult with his general practitioner, Dr John Bennett. David told Dr Bennett that the dreams had stopped and his memories were less frequent, but he felt that he had been drugged by his father.38 78 On the same day, he sent his friend a message saying 'when I turn up dead in 2 days. You take this forward'. He said he had spoken to a lawyer and that he will 'FOI' Joondalup Childrens Court the following day.39 79 That day, David also filled out on online report made through Safe2Say, which is a platform developed by Crime Stoppers WA.40 80 On 22 January 2025, David sent messages to his friend talking about how drugs he was given as a child stunted his growth and affected his brain development. He sent messages like: (a) 'Even though my dad had been drugging me a lot. When I was 9, I was on the taller side of the class..'; (b) 'the gov made him stop at the end of year 11…'; (c) 'He also starved me as much as he could'; (d) 'He did it to Andrew too'; and (e) 'I get monitored by researchers.' 81 David told his friend that a friend's parents tried to help him escape, so as punishment, the State made them drug his friend.41 82 David's older brother, Hany, has said that his parents were loving and there was 'absolutely no incident in my childhood that would reflect what David said in the report'. 42 37 Exhibit 1 [14]. 38 Exhibit 1 [15]. 39 Exhibit 1 [15]. 40 Exhibit 1 [16]. 41 Exhibit 1 [17]. 42 Exhibit 1 [17.1]. -- 20 of 41 -- [2026] WASC 164 PALMER J Page 21 83 David's younger brother, Andrew, has said that he strongly disagreed with David's claims of abuse or neglect. Andrew said that 'my childhood was amazing. I had the best mum and dad. It was beautiful, I wish I could go back to those times … there were never any issues with any of my siblings growing up. We had a great childhood'. 43 27 January 2025: David resolves to kill his father 84 On or about 27 January 2025, David decided to kill his father as he believed that his father was responsible for sexually and physically abusing him and neglecting him as a child.44 85 David drove his 2010 Mercedes E63 from his home in Bald Hills, Queensland, to his father's home in Clarkson, Western Australia. He brought a large Japanese kitchen knife with him.45 86 David took photographs at various places along the drive from South Australia to Western Australia.46 29 January 2025: David is stopped by police in South Australia 87 On 29 January 2025, police in South Australia received calls from members of the public who had seen David's car speeding along Eyre Highway with its rear bumper hanging off.47 88 At some point that day David had hit one or more kangaroos.48 89 David was pulled over by a police officer at 1.58 pm. David had been driving 79 km over the speed limit.49 90 David told police that he was relocating from Queensland to Perth and that his reason for speeding was that he was low on fuel, and that he could only fill up with 98 octane.50 91 David was calm. The police saw a knife in the passenger side footwell, with grey duct tape next to it. David told the police that he had been using the knife to cut the duct tape he was using to fix the 43 Exhibit 1 [17.2]. 44 Exhibit 1 [18]. 45 Exhibit 1 [19]. 46 Exhibit 1 [20]. 47 Exhibit 1 [21]. 48 Exhibit 1 [22]. 49 Exhibit 1 [23]. 50 Exhibit 1 [24]. -- 21 of 41 -- [2026] WASC 164 PALMER J Page 22 bumper on his vehicle. The police briefly seized the knife but gave it back to David. The police got David to duct-tape his bumper and fined him.51 31 January 2025: David arrives in Perth 92 About 2.40 am on Friday 31 January 2025, David arrived in Clarkson in suburban Perth. He drove to a location within walking distance of his father's house. He parked his vehicle nearby because he did not want to alert his family or their neighbours to his presence.52 93 David walked to his father's house holding the knife, intending to wake his father and kill him.53 94 David entered the house and found no one home. He decided to wait until his father returned home.54 95 David called his brother, Andrew, but Andrew did not answer.55 96 At 3.18am, David messaged his friend on WhatsApp saying that his family have gone into hiding because he came home, the door was unlocked and the house is pristine. David also referred to his family drugging him and the government being in on it.56 97 Later on, and throughout the day, David sent his friend messages accusing his dad, family, and the government of drugging him whilst he was a child. He also said he is 'Ready to kill all who enter … especially small children'. He said that the police took his family into protection so that he could not kill them. He also said that about seven months ago the memories started coming back, like 'leaks' and then there was a 'flood around December'.57 1 February 2025: David waits for his father at his father's house 98 On Saturday 1 February 2025, David parked his car in the garage of his father's house. His brother, Andrew, texted him that his father, Theresa, and Angela were on holiday in Thailand and would all be 51 Exhibit 1 [25]. 52 Exhibit 1 [26]. 53 Exhibit 1 [27]. 54 Exhibit 1 [28]. 55 Exhibit 1 [29]. 56 Exhibit 1 [30]. 57 Exhibit 1 [30]. -- 22 of 41 -- [2026] WASC 164 PALMER J Page 23 returning on Wednesday 5 February 2025. Andrew did not know that David was at his fathers' house.58 99 David remained at the house, waiting for his family to return. He did not go out as he did not want to alert anyone to his presence at the house.59 100 David exchanged Whatsapp messages with his friend in which: (a) his friend asked why David did not stop and sleep on his drive over to which David replies, at 12.27 pm 'Adrenaline' followed by 'On my way to ki…I mean see my father'; (b) David mentioned the researchers saying that they would get into trouble if 'they' killed his father but he wouldn't; (c) David said 'you see. They made me deal with my dad'; and (d) David said that his brother Andrew contacted him and informed him that his dad and family were in Thailand and return Wednesday and David said 'Feb 5th…which is also my deadline'.60 3 February 2025: David speaks to his general practitioner 101 On 3 February 2025, David again had a telephone consult with his general practitioner. Dr Bennett's clinical notes state: 61 is in Perth at present. Has some things to do with the police there in person. Staying in his fathers' house as his younger brother had told him that his father is in Thailand. Has spoken with a lawyer in WA. Recalling more memories of past abuse. Denies homicidal or suicidal intent - says he will do this through the police. He had hit 2 kangaroos on the way over to Perth. Isn't taking dexamphetamine or cannabinoids - says he stopped this since Dr Batts has asked him to stop. 102 At 10.12 pm David sent a text message to his general practitioner which said 'God help me Dr Bennett'.62 58 Exhibit 1 [31]. 59 Exhibit 1 [32]. 60 Exhibit 1 [33]. 61 Exhibit 1 [34]. 62 Exhibit 1 [35]. -- 23 of 41 -- [2026] WASC 164 PALMER J Page 24 4 February 2025: David's family returns home 103 At 5.15 am on 4 February 2025, Andrew picked up his father, Theresa and Angela from the airport and drove them to his house. At about 6.00 am, Nadi drove Theresa and Angela back home from Andrew's house.63 104 David woke up to hearing Theresa and Angela talking in the kitchen. They were not expecting David to be there. They opened the garage door and saw David's car parked in the garage.64 105 David told them that he had come to stay with them for about a week. David asked Angela to come with him to the front of the house, through the garage, telling her that he wished to speak with her parents alone. He did not want Angela to witness what he was going to do next.65 106 David returned to the kitchen holding a knife. David put the knife on the kitchen bench and Theresa moved the knife a little. Theresa noticed that Angela was not there and that David looked angry.66 107 David picked up the knife and pointed it at his father and said 'I remember when I was young. I remember things from when I was young. I never forget anything. I want to kill'.67 108 David made a motion with the knife as if to cut his own neck. David pointed the knife at his father and said 'You two sit down here. I want to kill you both. Sit down together. I remember when I was young. I am going to kill you both'.68 109 Theresa said to David 'I was not there when you were young. What happened?' David did not answer but said 'sit here and I will call the police'. Nadi asked David to relax.69 110 Nadi and Theresa both tried to convince David to drop the knife. When he refused, they tried to wrestle the knife out of his hand. During this struggle, David pushed his father's head against a wall. His father screamed out in pain and moved away down the hallway to the front 63 Exhibit 1 [36]. 64 Exhibit 1 [37]. 65 Exhibit 1 [38]. 66 Exhibit 1 [40]. 67 Exhibit 1 [41]. 68 Exhibit 1 [41]. 69 Exhibit 1 [42]. -- 24 of 41 -- [2026] WASC 164 PALMER J Page 25 door. Angela was ringing the doorbell, and Nadi opened it to let her in.70 111 David was angry at his father for letting Angela in and told all three of them to go out the front of the house. Nadi and Angela went outside. Theresa was still holding David's hand with the knife and the knife cut her as she and David moved outside.71 112 Theresa told Angela to run. At that stage, Nadi was near the letterbox. Theresa could see David waving the knife around. Theresa saw Angela run to the end of the road.72 113 Nadi tried to avoid David by moving around behind his car which was parked on the driveway.73 114 Angela came back and said 'mum did you get wounded' but Theresa told her that she was ok and to go away.74 115 Theresa went toward Nadi who was near their car, and Nadi told her to call an ambulance. David moved around toward Nadi from the other direction and stabbed him twice in the back very fast. Nadi fell to the floor.75 116 Theresa put out her hands to try to protect Nadi and felt the knife cut her hand. She also felt the knife in her arm. She did not feel getting stabbed in the stomach.76 117 Theresa sustained a laceration to her right hand, a laceration to her left forearm, and a penetration wound to her abdomen (upper left quadrant).77 118 David stabbed Nadi several more times (Theresa cannot recall how many). David then stepped back and said 'I'm sorry dad'. David then stepped forward and stabbed Nadi to the heart and then walked away.78 70 Exhibit 1 [43]. 71 Exhibit 1 [44]. 72 Exhibit 1 [45]. 73 Exhibit 1 [46]. 74 Exhibit 1 [47]. 75 Exhibit 1 [48]. 76 Exhibit 1 [49]. 77 Exhibit 1 [50]. 78 Exhibit 1 [57]. -- 25 of 41 -- [2026] WASC 164 PALMER J Page 26 A neighbour witnesses the attack 119 The attack was witnessed by a neighbour. He heard yelling and screaming from inside Nadi's address. At first, he thought that David appeared to be punching Nadi in the abdomen and chest area. He saw six motions of moderate force. When David turned towards him, however, he saw that David was holding a knife in his hand.79 120 The neighbour also saw Theresa being struck or slashed to the arm and hand area by David.80 121 There is also door-bell Ring footage from the house next door which shows Angela running away. David and Theresa can be seen on the top left-hand side out the front of the house, and Theresa can be heard screaming. David still had the knife in his hand for a time. David can then be seen on the phone.81 David calls 000 122 After the stabbing, David called 000 and he informed the operator that he had killed his father. David is very calm on the phone. He simply says, 'I killed my father...I stabbed him outside the house'. David said that he's a few metres away from his father. 123 The paramedic continuously asked about the victim's health symptoms and David kept replying 'he's dead'. 124 The operator said that she would give David advice about how to help his father and he said 'I'm the killer, he's dead lady'. The operator said that if his father was still bleeding, he could still help to which David responded 'I stabbed him 50 times, in the heart'. 125 David said he also stabbed 'his wife once' but it was an accident because she got in the way. The operator asked why he did it, to which he said 'I remember things he did to me when I was young - child molester - psychopath'. David then said that the police had arrived so he had to go.82 79 Exhibit 1 [54]. 80 Exhibit 1 [55]. 81 Exhibit 1 [58]. 82 Exhibit 1 [59]. -- 26 of 41 -- [2026] WASC 164 PALMER J Page 27 Emergency services arrive 126 The police were the first emergency responders on the scene.83 127 One police officer, Senior Constable Rixon, saw blood on David's hands and asked him if he had a knife on him. David said no. The Senior Constable handcuffed David and brought him to the police van. David told the Senior Constable that the knife was inside.84 128 David was arrested. He was observed to be calm and quiet when put into the back of the police van.85 129 St John of God's Ambulance paramedics arrived at 6.42 am. One officer observed multiple stab wounds on Nadi. He was certified life extinct at 6.49 am.86 130 A fingerprint on the knife was subsequently identified as belonging to David and a number of blood stains were identified as belonging to Nadi.87 131 David was taken to the Joondalup police station arriving at 8.20 am. He was there for an hour before he was taken to Joondalup Hospital.88 David is taken to the hospital 132 David was assessed in the Emergency Department by a Registrar. She asked David 'do you know why you are here?' to which he replied 'Because I killed my father'.89 133 A blood sample was taken from David. He had no alcohol in his system and tested negative for illicit substances.90 134 At 12.44 pm, David returned to the Joondalup Police station.91 83 Exhibit 1 [61]. 84 Exhibit 1 [62]. 85 Exhibit 1 [63]. 86 Exhibit 1 [64]. 87 Exhibit 1 [65]. 88 Exhibit 1 [66]. 89 Exhibit 1 [67]. 90 Exhibit 1 [68]. 91 Exhibit 1 [70]. -- 27 of 41 -- [2026] WASC 164 PALMER J Page 28 The police interview David 135 At 6.47 pm on 4 February 2025, David was interviewed by the police. He admitted the offences.92 During the interview David said the following: (a) that he did it and went there with intent to kill his father;93 (b) he told his dad he remembered everything and he pulled out the knife;94 (c) his father ran outside. He stabbed his father several times to make sure he was dead. He wanted him to die quickly as he did not want him to suffer. He told him he was sorry as he lay on the ground, before he died;95 (d) Theresa tried to grab the knife but it cut her. The injury was an accident;96 (e) he then called the police;97 (f) he left Queensland in his car on 27 January;98 (g) the knife was a Japanese knife that he has had a while.99 (h) someone told him to kill his father. His eyes were closed at the time. He spoke to those researchers (an actual person when he was 15 years old) once or twice a year. They told him it was his home if he did it. In his mind it was the only way to end the study. The drugs make him see the researchers;100 (i) his father would lock him in a room for hours and days at a time. His father was involved in a molestation syndicate where older men would come, drug him, and molest him. The sexual abuse stopped at when he was around eight or nine years old, 92 Exhibit 1 [72]. 93 Exhibit 1 [73.1]. 94 Exhibit 1 [73.6]. 95 Exhibit 1 [73.7]. 96 Exhibit 1 [73.8]. 97 Exhibit 1 [73.9]. 98 Exhibit 1, [73.10]. 99 Exhibit 1 [73.11]. 100 Exhibit 1 [73.12]. -- 28 of 41 -- [2026] WASC 164 PALMER J Page 29 but the neglect continued until he moved out of home when he was 18 or 19;101 and (j) he has been seeing a psychiatrist since 2023 for ADHD.102 David is admitted to the Franklyn Centre 136 David was then admitted to the Franklin Centre. He was diagnosed with psychosis and treated with antipsychotics.103 Count 1: David unlawfully killed Nadi 137 I am satisfied beyond reasonable doubt that David unlawfully killed Nadi. 138 I have found that David stabbed him repeatedly with a knife, including stabbing him in the heart. Nadi was pronounced dead by ambulance officers, shortly after the attack. Count 2: David omitted to do an act that it was his duty to do 139 I am satisfied beyond reasonable doubt that David omitted to do an act that it was his duty to do, as a result of which the life, health or safety of Theresa was, or was likely to be, endangered. 140 I am satisfied beyond reasonable doubt that David omitted to wield the knife safely and properly, so as to avoid endangering Theresa’s life, health, and safety. I consider that in his frenzied attack on his father, David failed to pay any attention to where Theresa was or take any steps to avoid injuring her. He was focused on his attempts to stab his father. 141 I am satisfied beyond reasonable doubt that David was under a legal duty to use the knife in a manner that did not endanger and would not be likely to endanger Theresa's life, health, and safety. Knives are dangerous and capable of causing serious injury or death if insufficient care is taken in their use. 142 I am satisfied beyond reasonable doubt that the manner in which David used the knife endangered and was likely to endanger Theresa's life, health or safety. The manner in which he used the knife could easily have seriously injured her and she was in fact wounded. 101 Exhibit 1 [73.13]. 102 Exhibit 1 [73.14]. 103 Exhibit 1 [71]. -- 29 of 41 -- [2026] WASC 164 PALMER J Page 30 Dr Adam Brett's evidence 143 The defence called Dr Adam Brett to give evidence. He is a consultant psychiatrist. He qualified in medicine in 1990 and has been a member of the Royal Australian and New Zealand College of Psychiatrists since 1999. He was the director of the Community Forensic Mental Health Service between 2001 and 2009. 144 Dr Brett prepared four reports dated 30 April 2025,104 23 October 2025,105 26 March 2026,106 and 20 April 2026,107 that were tendered by consent. 145 The prosecution did not call an expert psychiatrist and did not contest Dr Brett's opinion. Dr Brett's report dated 30 April 2025 146 To prepare his first report, Dr Brett interviewed David twice at the Frankland Centre, on 26 February 2025 and 18 March 2025. He also liaised with David's treating team, his previous treating psychiatrist, and reviewed David's medical records.108 147 When Dr Brett first interviewed David, David described being abused by his father. Dr Brett considered that his account was consistent with delusional beliefs. David described being locked in a room by his father for two years from the age of three to five.109 148 David told Dr Brett that the Department of Child Protection were involved in his care but that his father took the Department to court and he lied for his father.110 149 He said that his father tried to drown him when he was aged seven, tried to pay off lifeguards, and tried to make his arm bands get stuck below the ropes.111 150 David told Dr Brett that his father paid $200 to students to bully him in school and that his father drugged him and prostituted him out to 104 Exhibit 10. 105 Exhibit 11. 106 Exhibit 12. 107 Exhibit 13. 108 Exhibit 10, page 2. 109 Exhibit 10, page 2 [4]. 110 Exhibit 10, page 2 [5]. 111 Exhibit 10, page 3 [6]. -- 30 of 41 -- [2026] WASC 164 PALMER J Page 31 child molesters. He said that he had watched his mother and sister being gang raped which was organised by his father.112 151 David said that he believed he had been recruited into a research trial due to his high intelligence and his resilience to human trauma when he was nine. He said that a lawyer and federal police were involved and that he recalled them taking photos of him and playing games with him to teach him how to be resilient to bullying. He said that he had been attached to a lie detector.113 152 David said that the abuse stopped when he was aged 12, when the government became involved.114 153 David told Dr Brett that he had made a freedom of information application to the Department of Child Protection but they had no record of him.115 154 He said that the people who ran the study would contact him every year to review his progress. He said that he saw them in a dream like state.116 155 David said to Dr Brett that he had seen his general practitioner in late 2024 when his mental health deteriorated. He said that he had been using marijuana oil and dexamphetamines (which had been prescribed), and his general practitioner and psychiatrist had told him that he was psychotic and told him to stop using drugs. He was also prescribed an antipsychotic (risperidone). He stated that he did not use drugs after his doctors told him to stop.117 156 David told Dr Brett that the memories became more prominent and that the researchers were communicating with him in dream like states. He stated that he became aware through the researchers that he had to kill his father to end the studies and that he had no choice. He believed that agencies were covering up his abuse.118 157 David told Dr Brett that he made the decision to kill his father based on his dreams and memories.119 112 Exhibit 10, page 3 [7] - [9]. 113 Exhibit 10, page 3 [11] - [12]. 114 Exhibit 10, page 3 [13]. 115 Exhibit 10, page 3 [14]. 116 Exhibit 10, page 4 [15]. 117 Exhibit 10, page 4 [15]. 118 Exhibit 10, page 4 [16]. 119 Exhibit 10, page 4 [17]. -- 31 of 41 -- [2026] WASC 164 PALMER J Page 32 158 David told Dr Brett that in the two days before the attack he felt his life fell apart. He said that he lost his job, failed his studies, his girlfriend dumped him, and he was evicted from his accommodation. He blamed his father for all of these events.120 159 David told Dr Brett that he did not mean to stab his stepmother and was remorseful for this. He believed that killing his father was the right thing to do.121 160 David said that he has had no communication from the study people since then, and that he would be given a new identity and would not go to prison.122 161 By the second time that Dr Brett interviewed David, Dr Brett considered that David had responded to treatment and gained some insight into his psychopathology. Dr Brett said that David understood that he was not in a study and that it was unlikely that his father was trying to kill him. Dr Brett did not think that David had achieved complete insight and said that he still struggled with whether his memories were real or delusional.123 162 Dr Brett said that the Department of Child Protection have no record of David.124 163 Dr Brett also said that he understood that David's brother had confirmed that none of the stories of abuse were true.125 164 Dr Brett set out his understanding of David's prior psychiatric history,126 his previous medical history,127 his substance abuse history,128 his family history129 and his personal history.130 165 Dr Brett conducted a mental state examination. He reported that there were no acute risk issues and that David's risk to himself is likely 120 Exhibit 10, page 4 [18]. 121 Exhibit 10, page 5 [21]. 122 Exhibit 10, page 5 [22]. 123 Exhibit 10, page 5 [24]. 124 Exhibit 10, page 5 [29]. 125 Exhibit 10, pages 5 - 6 [30] - [31]. 126 Exhibit 10, pages 6 - 10 [33] - [61]. 127 Exhibit 10, page 10 [62] - [66]. 128 Exhibit 10, page 11 [70] - [73]. 129 Exhibit 10, page 11 [70] - [73]. 130 Exhibit 10, pages 11-12 [74] - [81]. -- 32 of 41 -- [2026] WASC 164 PALMER J Page 33 to increase when he gains insight into his mental health and offending behaviour.131 166 Dr Brett diagnosed David as suffering from a mental illness in the schizophrenia spectrum and ADHD.132 167 Dr Brett said that David developed a psychotic episode while taking prescribed dexamphetamine and medicinal marijuana. He said that David had been treated by a psychiatrist in Queensland who had diagnosed him with psychosis, told him to stop taking dexamphetamine and marijuana, and prescribed the antipsychotic, risperidone.133 168 Dr Brett considered that the combination of the medication he had been taking and the significant stress he was under appeared to be significant factors in his development of psychosis. He thought that there was evidence of a decline in his functioning from the loss of his job, failing medical school, separating from his girlfriend, and losing his accommodation.134 169 Dr Brett thought that David's psychosis involved delusional beliefs about his father, whom he believed had abused him throughout his life and who was trying to kill him. He said that David believed that he was part of a research scheme, involving different government agencies.135 170 Dr Brett said that David believed that he had no choice but to kill his father, which he believed would end the research and his suffering. Dr Brett said that David believed that if he did not do this, his father would kill him.136 171 Dr Brett considered that David was suffering from a mental impairment, namely a mental illness in the schizophrenia spectrum.137 172 Dr Brett explained what he meant by 'a mental illness in the schizophrenia spectrum' during the following exchange that took place at trial:138 131 Exhibit 10, pages 12-13 [82] - [83]. 132 Exhibit 10, page 13 [84] - [85] and page 12 [5]. 133 Exhibit 10, page 13 [1]. 134 Exhibit 10, page 14 [2]. 135 Exhibit 10, page 14 [3]. 136 Exhibit 10, page 14 [4]. 137 Exhibit 10, page 14 [5]. 138 Ts 72. -- 33 of 41 -- [2026] WASC 164 PALMER J Page 34 Now ultimately, Dr Brett, your diagnosis of [David] is that he suffers schizophrenia?---I think I put in the report, schizophrenia spectrum, which is slightly different, and I'll explain that, if you want. Yes, I'd like you to, thank you?---Yeah. So usually, when people become first psychotic, we refer it to as first episode psychosis, and that's as it explains, it's the first episode that someone has become unwell. And the reason that that's changed, is because with longitudinal research it shows that the definitive diagnosis usually becomes apparent in a year or two. So some people go on to develop schizophrenia, some people get a bipolar effective disorder, or schizoaffective disorder. So it's difficult to predict how people are going to evolve. So schizophrenia spectrum incorporates a lot of those major mental illnesses. So I had no doubt he had a major mental illness, just wasn't sure which one of them he had. 173 Dr Brett considered that David's mental impairment deprived him of the capacity to know that he ought not do the act. Dr Brett thought that David believed that his life was in danger, that if he did not kill his father, his father would kill him, and that what he was doing was morally right. In Dr Brett's opinion, David also believed that the government would give him a new identity and that he would not go to prison.139 174 Dr Brett explained that he had reached this conclusion based on information about David prior to the offence, including his psychiatrist diagnosing him and treating him for psychosis. He also referred to David's psychologist noting his psychosis and his homicidal ideation whilst he was in Queensland.140 175 Dr Brett also said that he attached significance to David's admission to hospital after the offence and his diagnosis then as suffering from psychosis and treatment with antipsychotics. He also thought that the history that David gave him when he examined him was consistent with psychosis.141 176 Dr Brett thought that David's precise diagnosis was presently unclear. He said that David may have had a psychotic episode secondary to the medication he was prescribed and the stress that he was under.142 139 Exhibit 10, page 14 [8]. 140 Exhibit 10, pages 14-15 [9]. 141 Exhibit 10, page 15 [10] - [11]. 142 Exhibit 10, page 15 [12] - [13]. -- 34 of 41 -- [2026] WASC 164 PALMER J Page 35 Dr Brett's report dated 23 October 2025 177 Dr Brett's second report was prepared after David's solicitors provided him with further material, including text messages he sent, witness statements prepared by the police, a statement of material facts, the 000 call made by David, and David's police interview. Dr Brett summarised that material in his report.143 178 Dr Brett thought that the further material supported his original opinion.144 179 Dr Brett reported that the material provided revealed that David had a relatively normal upbringing. He said that there was no evidence of abuse and he had a loving relationship with his parents. He said that there was no evidence of personality pathology.145 180 Dr Brett thought that the material provided supported the conclusion that David developed psychosis some time before the offence occurred. He said that David believed that he had been abused and drugged by his father and involved in a research experiment that was orchestrated by the government and his father. He said that David believed that the only way to stop the abuse and the experiment was to kill his father, and his functioning declined.146 181 Dr Brett considered that there was evidence that David's thought processes were not clear. He said that this was evident from the fact that he failed university and was pulled over by the police whilst speeding excessively with his back bumper hanging off.147 182 Dr Brett thought that David's state of delusion was further confirmed by his 000 call, when he told the operator that he had killed his father because he had abused him and was a child molester and a psychopath. Dr Brett said that as there was no information to corroborate this belief, the behaviour is consistent with a delusion.148 143 Exhibit 11, pages 1-6 [1] - [34]. 144 Exhibit 11, page 7 [1]. 145 Exhibit 11, page 7 [2]. 146 Exhibit 11, page 7 [3]. 147 Exhibit 11, page 7 [4]. 148 Exhibit 11, page 7 [5]. -- 35 of 41 -- [2026] WASC 164 PALMER J Page 36 183 Dr Brett noted that David was subject to drug testing after the offence and this confirmed that there was no evidence of intoxication at the time of the offending.149 184 Dr Brett considered that during his police interview, David's affect was abnormal to the content of the interview, and his presentation was consistent with a man who was experiencing a psychotic episode.150 185 Dr Brett concluded that there was good collateral information to support his previous opinion that David was psychotic before the offence and after the offence, when he made the 000 call and was interviewed by the police. Dr Brett thought that David was acutely unwell at the time of the offence.151 186 Dr Brett noted that people with mental disorders can plan as David did but he said that the planning was based on delusional beliefs.152 Dr Brett's report dated 24 March 2026 187 Dr Brett prepared his third report after he was asked to comment about whether David's psychosis might have been induced by him taking seven to eight dexamphetamine tablets per day, rather than the six tablets per day he had been prescribed. 153 188 Dr Brett considered that although the scientific literature is not robust, it supports a conclusion that there is a dose-response relationship between medication and risk of psychosis.154 189 Dr Brett noted however that the difference in dosage between seven to eight tablets to the prescribed six tablets is minimal. He said it was theoretically possible that it may have made a difference. 155 190 Dr Brett believed that David had developed a schizophrenia spectrum disorder which would have made him more vulnerable to any factors that would increase his risk of psychosis. He said that these factors would include stress, marijuana and dexamphetamines. He thought that David had all of these risk factors and that his psychosis 149 Exhibit 11, page 7 [6]. 150 Exhibit 11, page 8 [8]. 151 Exhibit 11, page 8 [9] - [10]. 152 Exhibit 11, page 8 [11]. 153 Exhibit 12, page 1. 154 Exhibit 12, page 2 [6]. 155 Exhibit 12, page 2 [7]. -- 36 of 41 -- [2026] WASC 164 PALMER J Page 37 persisted in the absence of dexamphetamine and marijuana, suggesting an underlying mental disorder.156 191 Dr Brett noted that dexamphetamines have been used to treat the negative symptoms of schizophrenia and people who have schizophrenia and ADHD have been treated with dexamphetamines. He considered that although the medication increases the risk of psychosis, it has been used in people with schizophrenia safely.157 192 Dr Brett believed that it was possible that David may have not developed psychosis if he had taken his medication as prescribed but said this would be 'extremely unlikely'.158 193 Dr Brett concluded that David had a vulnerability to psychosis and that the stress he was experiencing, the dexamphetamines, and the medicinal marijuana all likely contributed to the emergence of his psychosis.159 Dr Brett's report dated 20 April 2026 194 Dr Brett's last report was prepared after the charge regarding Theresa was changed to the present charge. 195 Dr Brett considered that David was acting secondary to his psychosis. He said that this deprived him of the ability to exercise care in controlling the knife. He thought that given David's psychosis he was unable to reason with any degree of clarity. He believed that David was deprived of the capacity to manage the safety of the knife given his acute psychosis.160 196 Dr Brett said that he believed that David's main aim was to kill his father, driven by his psychosis. He said that David's psychosis impacted on his reasoning and his physical control. He said that David would have been in a state of acute distress and agitation, which would have impacted on his ability to physically control the knife and reason.161 197 At trial, Dr Brett explained that people who are in acute psychosis can be deprived of the ability to control their actions because they are 156 Exhibit 12, page 2 [8]. 157 Exhibit 12, page 2 [10]. 158 Exhibit 12, page 2 [10]. 159 Exhibit 12, page 2 [12]. 160 Exhibit 13, page 2 [6]. 161 Exhibit 13, page 2 [7]. -- 37 of 41 -- [2026] WASC 164 PALMER J Page 38 distracted by their psychosis. He suggested that the psychosis made David more impulsive. He thought that David was unable to exercise the ability to control his actions.162 Was David mentally impaired when he committed the offences? 198 Dr Brett's uncontradicted evidence was that when David committed the offences, he was suffering from a mental impairment, namely a mental illness in the schizophrenia spectrum.163 Dr Brett explained that it may take time to diagnose the precise mental illness in the schizophrenia spectrum.164 199 Both the prosecution and the defence submitted that Dr Brett's evidence was sufficient to establish that David was mentally impaired when he committed the offences. 200 Although Dr Brett's evidence was that the precise diagnosis of David's mental illness is presently unsettled, his opinion was that David was undoubtably suffering from a mental illness. That opinion was uncontested. 201 While I am not bound to accept and act upon Dr Brett's evidence, I am not entitled to disregard his evidence capriciously. I may only reject that evidence if there is some other evidence, fact or circumstance that contradicts it or warrants the conclusion that his evidence is unreliable. Otherwise, I must accept it. 202 I found Dr Brett's reasoning to be cogent and compelling. His conclusion that David was suffering from a mental illness is consistent with the contemporaneous evidence of delusional behaviour, including the texts that he sent. The conclusion is also consistent with the fact that the medical practitioners treating David in Brisbane in January 2025 thought that he was psychotic. 203 I do not consider that there is some other evidence, fact or circumstance that contradicts Dr Brett's evidence, or warrants a conclusion that the evidence is unreliable. I accept his evidence, and I am satisfied that at the time that David committed the offences, he had a mental illness and suffered from a mental impairment. 162 Ts 83 - ts 84. 163 Exhibit 10, page 14 [5]. 164 Ts 72. -- 38 of 41 -- [2026] WASC 164 PALMER J Page 39 Count 1: Did David lack the capacity to know he ought not do the act? 204 Dr Brett's evidence was that when David committed the offences, his mental impairment deprived him of the capacity to know that he ought not do the act. 205 Again, that evidence was uncontradicted and both the prosecution and the defence submitted that it provided a sufficient basis for me to find that Daivd was deprived of the capacity to know that he ought not kill Nadi. 206 I again found Dr Brett's reasoning to be cogent and compelling. His conclusions were again consistent with the contemporaneous evidence of delusional behaviour and the concerns expressed by the medical practitioners treating David in Brisbane. 207 I do not consider that there is some other evidence, fact or circumstance that contradicts Dr Brett's evidence, or warrants a conclusion that it is unreliable. I accept his evidence, and I am satisfied that at the time that David unlawfully killed Nadi, he was deprived of the capacity to know that he ought not kill Nadi. Count 2: Did David lack the capacity to control his actions? 208 Dr Brett's evidence was that David's psychosis deprived him of the ability to exercise care in controlling the knife. He thought that David's psychosis meant that all of David's attention was focused on trying to kill his father and he was unable to give attention to whether Theresa might be injured by his actions. 209 The evidence was again uncontradicted and both the prosecution and the defence submitted that it provided a sufficient basis for me to find that Daivd was deprived of the capacity to control his actions, when he failed to adequately control the knife to avoid injuring Theresa. 210 I do not consider that there is some other evidence, fact or circumstance that contradicts Dr Brett's evidence, or warrants the conclusion that the evidence is unreliable. I accept his evidence, and I am satisfied that David lacked the capacity to control his actions at the relevant time. -- 39 of 41 -- [2026] WASC 164 PALMER J Page 40 Verdict on both counts: Not guilty on account of mental impairment 211 I find David not guilty on both counts on account of mental impairment. Whether David intended to kill Nadi 212 While the identification of a specific intention can be difficult in cases where an accused was suffering from a mental impairment at the relevant time, there are nevertheless cases in which it is possible to reach a positive conclusion about intention, even if it is the product of a delusion. In The State of Western Australia v McCullock [No 2],165 the Chief Justice observed that where there is reliable evidence to support a finding of an intention to kill (albeit an intention that was the result of a delusion caused by a mental impairment) it may be appropriate for the trial judge to make specific findings in relation to those issues. 213 In this case, David's attack on his father was premeditated and planned. He drove from Brisbane to Perth to kill him and brought a knife with him to use. He waited for his father to return home for several days. He stabbed his father repeatedly, including in the heart. He has admitted to intending to kill his father. 214 Ultimately, I consider that the evidence establishes beyond reasonable doubt that David intended to kill Nadi, although that intention was the result of a delusion caused by his psychosis. Conclusion 215 For these reasons, I find David not guilty on both counts on account of mental impairment. 216 It will now be necessary for me to make an order regarding David under pt 5 of the CLMI Act. Another hearing may be required for that purpose. I will hear from the parties about the appropriate orders that should be made to progress matters. 165 The State of Western Australia v McCullock [No 2] [2024] WASC 400 [134] - [136]. -- 40 of 41 -- [2026] WASC 164 PALMER J Page 41 I certify that the preceding paragraph(s) comprise the reasons for decision of the Supreme Court of Western Australia. CN Associate to the Honourable Justice Palmer 1 MAY 2026 -- 41 of 41 --