On the 4th of November, 2021, Diego Costa Silva took the life of his wife in their Finglas, Dublin residence while battling cannabis-induced psychosis. Despite being held on trial for the murder of Fabiola De Campos Silva, a jury found him blameless, attributing his actions to insane compulsion. Throughout the trial, insight was provided by two seasoned forensic psychiatrists into his psychological state, which included auditory hallucinations, delusions, and intense paranoia.
Dr Mark Joynt offered an explanation to the court, stating that Mr Costa Silva’s (aged 35) comprehension of his actions was hindered by his mental instability, leading him to believe that his misconduct was justified, and leaving him incapable of resisting his urges. The term psychosis is often associated with a person losing their connection with real world situations, as defined by Prof Des Crowley, Assistant Director of Substance Misuse at the Irish College of General Practitioners. He went on to clarify that psychotic people may misjudge reality, such as interpreting television broadcasts as personal messages or suspecting ill-intent from innocent chatter.
Furthermore, hallucinations, which may involve hearing non-existent voices or experiencing false visions, can also be a symptom of psychosis. In these instances, they might believe they are being instructed to harm themselves or others, as mentioned by Prof Crowley. In the case of Mr Costa Silva, he was convinced that his wife had become a vessel for an evil serpent intent on ending his life.
According to Prof Crowley, cannabis-induced psychosis is most often associated with prolonged, heavy use of the drug. Those with previous brain injuries, a family history of mental issues, or concurrent usage of other substances are more likely to develop such a disorder. As disclosed during the trial, Mr Costa Silva revealed to Dr Joynt that his habitual use of cannabis started at 16 and by 20, he was a daily smoker, whilst also having a family history of bipolar disease.
Crucially, Prof Crowley pointed out that the onset of psychosis stemming from cannabis use doesn’t necessarily limit to the time frame of intoxication, but potentially extends over a longer period. If individuals fail to revert back to their original mental state after roughly a month, the possibility of an ongoing mental disorder, like schizophrenia, should be considered as a diagnosis.
Psychotic symptoms continued to be exhibited by Mr Costa Silva for 11 days after he committed murder, despite his he claimed to have abstained from cannabis use leading up to the fatal incident. Following a conversation with Dr Joynt in November of the prior year, it was reported that there was no detection of currently active psychotic symptoms in Mr Costa Silva, which resulted in him not being diagnosed with a lingering ailment like schizophrenia.
Notably, there is a family history of bipolar disorder in Mr Costa Silva’s lineage, which puts him at an elevated risk of succumbing to a serious mental illness, including substance-induced psychosis.
Defence and prosecution barristers informed the jury that, under the Criminal Law (Insanity) Act 2006, Mr Costa Silva cannot be held legally accountable for his actions and therefore is eligible for the unique verdict of not guilty on the grounds of insanity.
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