A 35-year-old man who killed his wife because he believed she was possessed and had become a serpent, was suffering from a psychotic disorder induced by cannabis, the Central Criminal Court has been told.
Consultant forensic psychiatrists for the defence and for the prosecution agreed on the diagnosis for Diego Costa Silva who has pleaded not guilty to the murder of his wife, 33-year-old Fabiole Campara de Campos Silva.
Both psychiatrists agreed that Mr Costa Silva met the legal criteria for the jury to bring in a verdict of not guilty by reason of insanity.
The jurors heard evidence from consultant psychiatrist Dr Brenda Wright on behalf of the defence. She told the jury that on 4 November 2021, when Diego Costa Silva killed his wife, he was suffering from a cannabis-induced psychotic disorder.
She said such a disorder involves delusions, hallucinations and abnormal thought processes. When he killed his wife, she said, Mr Costa Silva did not know the nature and quality of his act. He understood his actions would result in her death, the psychiatrist said, but he believed his wife was possessed, had become a serpent and posed a threat to his life.
Dr Wright said it was notable during Mr Costa Silva’s interviews with gardaí afterwards that he was suffering from thought disorder, which she said was a core feature of a psychotic state. She said he was also hearing voices and other auditory hallucinations.
She said it was clear Mr Costa Silva had been using cannabis for a very long period of time and she had to assess the role the drug may have played in altering his mental state. He had only had two brief incidents in previous years where he had become paranoid after using the drug, but in the weeks leading up to the killing, she said his psychotic state had become much more enduring and much more preoccupying.
She said there was a difference between intoxication – where someone experiences symptoms while they are taking a drug and immediately afterwards – and the more prolonged psychosis experienced by Mr Costa Silva.
Psychiatrist Mark Joynt, called on behalf of the prosecution, agreed with Dr Wright’s diagnosis.
Dr Joynt said Mr Costa Silva’s mother, aunt and sister had all been diagnosed with Bipolar Affective disorder which meant that he was more vulnerable to developing a mental illness such as a psychotic disorder.
Dr Joynt said the symptoms in Mr Costa Silva’s case had begun a number of days before the killing and had continued for almost two weeks afterwards.
He was detained under the Mental Health Act two days before the killing and brought to the Mater Hospital where he was assessed. He was prescribed and administered an anti-psychotic medication at the hospital and given the option of remaining there as a voluntary patient but he chose not to do so, Dr Joynt said.
The court heard that doctors in the Mater spoke to his wife who told them she had seen a very sudden change in his behaviour a number of days previously when he had become paranoid and believed she would hurt him.
When she arrived in the area to pick him up from hospital, he initially hid from her, the court heard.
At the time he killed his wife, Dr Joynt said Mr Costa Silva believed she had been possessed by a gang leader from Brazil who was a serpent.
He cut her head off after attacking her because he believed it was the only way to kill the serpent. Dr Joynt said Mr Costa Silva was hearing voices and believed the gang leader was controlling his body.
During garda interviews he tried to injure his eyeballs as he believed the gang leader was seeing through his eyes.
Dr Joynt said Mr Costa Silva was administered anti-psychotic medication on 12 November but continued to show psychotic symptoms until 15 November, 11 days after the killing.
This indicated that he was suffering from a psychotic disorder, Dr Joynt said, rather than from the effects of cannabis intoxication where the symptoms come on while the drug is being used but resolve after drug use stops.
Dr Joynt agreed that Mr Costa Silva did not know what he was doing was wrong when he killed his wife and also found that he could not stop himself from killing her.
Lawyers for the prosecution and the defence said the evidence about Mr Costa Silva’s mental state all pointed one way.
Prosecuting counsel Shane Costelloe said the jurors may ask how someone who is abusing substances can rely on that for a defence.
He said it was not a case about intoxication as if it was the judge would tell them it was not a defence. The evidence was that Mr Costa Silva was suffering from a cannabis induced psychotic disorder which was a recognised mental disorder under the legislation.
Mr Costello said it was a particularly horrible and deeply tragic case. A young woman had lost her life and Mr Costa Silva had killed the woman he was married to for years.
Defence counsel, Garnet Orange told the jurors to put aside any views they had about domestic violence or cannabis use or any feelings of sympathy or horror. He said the evidence only pointed in one direction and only one verdict was possible – a verdict of not guilty by reason of insanity.
The jurors in the trial will begin considering their verdict tomorrow morning after Judge Michael McGrath finishes his charge to them.
