DIEGO COSTA SILVA, who cut his wife’s head off while suffering from a cannabis-induced psychosis, has been found not guilty of her murder by reason of insanity by a jury at the Central Criminal Court.

Costa Silva (35) pleaded not guilty to murdering Fabiola De Campos Silva (33) on 4 November, 2021 at their home in Charlestown Place, Finglas, Dublin 11.

His trial heard that due to his mental disorder, Costa Silva had come to believe that his wife was possessed by a serpent and that she would kill him.

After he attacked her, by striking her on the head with a mug, strangling and stabbing her, he cut her head off believing that he had to do so to make sure the serpent was dead.

Two forensic consultant psychiatrists gave evidence that Costa Silva was suffering from cannabis-induced psychosis with symptoms including paranoia, delusions and auditory hallucinations.

As a result of his illness he did not know the nature and quality of his actions and did not know that what he was doing was wrong, the psychiatrists said.

Barristers for the defence and prosecution told the jury that Costa Silva was not legally responsible for his actions and qualified for the special verdict of not guilty by reason of insanity under the Criminal Law (Insanity) Act 2006.

The jury of seven men and five women took two hours and 24 minutes to come to their unanimous verdict.

Evidence

Garda Colin Miley told the trial that two days before the killing he was on bike patrol at about 3.20pm when he saw Costa Silva running barefoot, wearing only shorts on Middle Abbey Street in Dubiln. Gda Miley caught up with Costa Silva near the Spire on O’Connell St and found him to be distressed and disorientated, while his eyes were bulging and he was sweating profusely.

The garda noted cuts and grazes to his feet and said Costa Silva told him he had jogged from Finglas to the city centre and that he liked to jog barefoot. When asked if he was “okay”, Costa Silva said he was upset and depressed following an argument with his wife. He told Gda Miley that he had recently confessed to her that he had cheated on her by kissing another woman and he suspected his wife was having an affair or affairs as revenge for what he had done.

Gda Miley had a concern regarding Costa Silva’s mental health and detained him under section 12 of the Mental Health Act to be examined by a doctor. Costa Silva was taken to Store St Garda Station where he agreed to go to the Mater hospital to be assessed.

Doctors noted Costa Silva was displaying the early signs of a psychotic episode, including thought disorder, delusion and a paranoid belief that his wife might hurt him.

Ms De Campos Silva came to the hospital and told doctors that she noticed a sudden change in her husband’s behaviour the previous Saturday but she said he had not smoked cannabis for several days. Doctors asked Costa Silva to remain as a voluntary patient but he chose to leave the hospital the following afternoon, 3 November.

His wife picked him up and drove him home.

In his garda interviews, Costa Silva said he had a “fight” with his wife at about 6am. He said he wasn’t feeling safe and told detectives he has “hurt on my mind, a sound or vibration in my ear and a voice in my head.” He later complained of having “something electronic in my ear” and of hearing “so many voices”. 

He said he did not argue with his wife but the “fight” started because “I just felt if I didn’t do it she could do it to me.”

When gardai put it to him that his wife did not try to kill him, he replied that her behaviour “led me to believe she was going to try to kill me.”

He described his wife biting him on the leg and scratching his shoulder with her nails before he struck her on the head two or three times with a cup. He said he then began choking her before putting his foot on her neck. She fainted, he said, and he stabbed her “in her heart” before cutting off her head. He added: “I took her head, I took a knife and I cut her head.”

When asked why, he said: “How can I explain? Sometimes you have to behead somebody because this person is possessed.”

He described four knives that he used and said it took about ten minutes to remove her head. He called gardai ten or 15 minutes later.

Gda Peter Kilgallen told the trial that he arrived at Costa Silva’s apartment within minutes of receiving an emergency call. Members of the Garda Armed Support Unit (ASU) were already there and Gda Kilgallen stood behind one of them as he knocked on the door. Costa Silva answered wearing just shorts and flip-flops. He had blood on his body and wrists, the garda said, and he told gardai: “I think I killed my wife.”

The ASU members entered and after being informed that the body of a deceased female was inside, Gda Kilgallen arrested Costa Silva on suspicion of murder and handcuffed him. Gda Kilgallen entered the apartment and saw Ms De Campos Silva lying between the doorway of one room and the hall. Besides the injury to her head, he could see obvious stab wounds and a knife protruding from the hilt in the area of the left breast. 

Gda Kilgallen left the apartment and Costa Silva told him that his wife had “tried to kill me” and later said: “She took my heart, she took my head. I did that because she was cheating on me.”

State Pathologist Dr Heidi Okkers wrote that the cause of death was “decapitation” with blunt force trauma to the head and asphyxia as contributing factors. She noted other stab wounds and some bruises which could have been defensive in nature.

Costa Silva was charged with his wife’s murder and taken to Cloverhill Prison where he was assessed by psychiatrists. Dr Mark Joynt was approached by the Director of Public Prosecutions (DPP) to assess Costa Silva’s mental state at the time of the killing.

Costa Silva told Dr Joynt he had begun smoking cannabis aged 16 and from the age of 20 would smoke daily. In 2020, he said his wife told him he was smoking too much and he agreed to cut down. He did not think he had smoked cannabis in the days immediately prior to killing his wife.

Dr Joynt said that in the lead-up to killing his wife, Costa Silva came to believe that his parents were being held by a gang and that his wife was possessed by the leader of the gang, in the form of a serpent. He believed his possessed wife was going to kill him and that he had to kill her to defend himself, the doctor said. After he attacked his wife, Costa Silva believed “the serpent wasn’t dead and he had to cut the head off to make sure it was dead.”

During his detention, doctors noted that Costa Silva continued to show psychotic symptoms until 15 November, eleven days after the killing. Two days after that, when Costa Silva had spent five days taking the antipsychotic drug Olanzapine, he was reported to be improving and to have gained insight into his illness and what had happened.

When Dr Joynt last spoke to Costa Silva in November last year, he said he found no evidence of active psychotic symptoms. He said this was one of the reasons he did not diagnose Costa Silva with a more persistent illness such as schizophrenia.

Dr Joynt concluded that Costa Silva was suffering from a cannabis induced psychotic disorder, the symptoms of which included hallucinations and delusions regarding his wife. He said that he excluded intoxication as a diagnosis because the symptoms persisted for eleven days after the killing, a period in which Costa Silva did not have access to drugs. He said this would not be consistent with the effects of acute intoxication from cannabis, which typically wear off within hours.

In conclusion, Dr Joynt said that due to his mental disorder, Costa Silva did not know the nature and quality of his actions, did not know that what he was doing was wrong and was unable to refrain from his actions.

Dr Brenda Wright, who was called by the defence, said she agreed with most of Dr Joynt’s conclusions. The only significant  distinction, she said, was that she believed Costa Silva could have refrained from his actions by avoiding his wife, as he had done previously when suffering similar delusions.

In his closing speech to the jury Shane Costelloe SC for the DPP said the prosecution had proven beyond reasonable doubt that Costa Silva killed his wife and that when he cut her head off, he intended to kill her. He asked them to consider the evidence of the psychiatrists who both said that Costa Silva was suffering from a mental disorder and that he is not responsible in law for his actions.

“All of the evidence adduced points only one way,” he said, “and you must act upon the evidence.”

He said the jury may ask themselves how somebody can abuse illegal substances and rely on that as a defence. However, he added: “You heard from both psychiatrists that this is not intoxication, it is not taking drugs or alcohol and then going and doing something, that would not be a defence. This is not intoxication, this is a mental disorder – cannabis induced psychosis.”

Counsel described it as a “particularly horrible case” and a “deeply tragic case” in which a young woman lost her life and her husband finds himself having killed his wife with whom he had enjoyed an otherwise healthy relationship. He asked the jury to put aside emotion, sympathy and personal feelings and view the evidence dispassionately.

If they find that Costa Silva did have a mental disorder that removed his responsibility for the crime, they must return a verdict of not guilty by reason of insanity, he said.

Orange, for the defence, said he agreed with everything said by counsel for the prosecution. He asked the jury to put aside any views they might have about drug use or domestic violence or any feelings of “disdain or horror” that they might ordinarily feel.