Judge finds Declan Sean Thomas not guilty of murdering father Edward Charles Thomas due to mental impairment

A man who killed his elderly father in Mandurah has been found not guilty of murder because he was suffering a mental impairment. Declan Sean Thomas, 35, pleaded not guilty in January 2022 to murdering Edward Charles Thomas in his Mandurah Terrance unit in July 2020, with his lawyer flagging he may seek a trial by judge-alone. That happened for not even a full day last week, when Supreme Court of WA Justice Fiona Seaward was told the shocking details of what took place. In her judgment handed down on Thursday, it was revealed that after killing the fragile 71-year-old, Thomas walked into Mandurah Police Station and declared: “I have just killed my dad”. He later told detectives that he attacked his father from behind while he was sitting in a chair, hitting him on the back of the head with a frying pan then placing him in a choke‑hold. They struggled on the floor before Thomas used a serrated kitchen knife to cut his throat. Thomas then held his hand. “He squeezed it and he left the world. That was that,” Thomas told them. He said the pair “never really got along ... but we weren’t complete enemies”, and his father was “getting older and older”. After mentioning “pain”, Thomas was asked to elaborate. “It’s not like he was years ago,” he said. Mr Thomas’ health had been deteriorating and he was using a gopher to get around. He had suffered a stroke, been diagnosed with asbestosis, and had had a knee replacement and a shoulder replacement. The court was told that Thomas began to suffer mental problems between the ages of 13 and 15, feeling paranoid about anything or anybody acting in an official capacity. He then became violent with family members and abusing drugs, which worsened his condition. Thomas once told his mother: “Old people should be put down when they are 60”. Justice Seaward said she was satisfied on the balance of probabilities that it was more likely than not Thomas was suffering a mental impairment, which deprived him of the capacity to know he should not do what he did. “Therefore, I find that Mr Thomas cannot be considered criminally responsible for his actions and must be found not guilty,” the judge said. Justice Seaward detained Thomas under a custody order, with a limiting term of life imprisonment commencing from the date of the killing. Mr Thomas lectured in Indigenous studies at Murdoch University and was described by one of his neighbours, Linda Stephens, as a “very quiet, very intelligent” man who “kept to himself a lot”. Lifeline 13 11 14 Beyond Blue: 1300 224 636 National Alcohol and Other Drugs Hotline: 1800 250 015