Murder-accused who killed and decapitated his wife found not guilty by reason of insanity

Trial heard due to cannabis-induced psychosis, Diego Costa Silva did not know the nature and quality of his actions and did not know that what he was doing was wrong

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

WARNING: Some readers may find the following article upsetting

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.

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

His trial heard due to his mental disorder, Mr 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 he had to do so to make sure the serpent was dead.

Two forensic consultant psychiatrists gave evidence Mr 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 Mr 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.