A 46-year-old woman on trial, charged with murdering her flatmate, told gardaí that voices in her head made her stab him.
Mercy Peters has gone on trial at the Central Criminal Court, having pleaded not guilty by reason of insanity to murdering the 42-year-old in their South Dublin home.
The Sierra Leone native stabbed Tyrone McKenna to death on July 17, 2014, at the house they had shared in Marley Court, Rathfarnham. She entered her plea yesterday, and a jury of eight men and two women was sworn in to hear the two-day trial.
Sergeant David Bunn testified that both the accused and deceased had a history of mental health problems and were living with Mr McKenna’s father, Tom McKenna, at the time.
Sgt Bunn told Paul Burns SC, prosecuting, that Tom McKenna had gone out for a walk that Thursday afternoon. He had returned home to find his son lying on his back at the bottom of the stairs. He appeared motionless.
He said that Mr McKenna had gone to the kitchen, where the accused appeared unfazed and unconcerned. He rang for an ambulance and, while waiting, noticed blood in different locations, particularly upstairs.
The deceased had no pulse when the ambulance crew arrived, and he was pronounced dead at the scene.
A post-mortem exam later gave the cause of death as a stab wound to the trunk, which injured the left lung and left kidney. A stab wound to the left forearm was a contributory factor. This might have been a so-called defensive injury, and several bruises and abrasions may have been caused by a scuffle.
Sgt Bunn explained that, while the ambulance crew was in the house, the accused had said that she was going to the shops. However, the crew asked her to stay until the gardaí arrived.
Gardaí found her sitting on a sofa, listening to music on headphones. There appeared to be blood-staining on a tobacco pouch on the coffee table in front of her. She told them that she’d heard a thud but hadn’t gone to find out what it was.
She was taken to Dundrum Garda Station to provide a witness statement. As her home was now a crime scene, the gardaí organised food and a hotel room for her. However, she didn’t want to go and requested to stay in the station overnight.
Another garda noticed her talking to herself and counting on her fingers the following morning. When asked, she said she was talking to her spirits.
Sgt Bunn also spoke to her that morning, when she again declined the offer of accommodation before telling him that she wanted to leave.
“I want to see Mary Lou McDonald,” she said. “I want to change my statement.
"I stabbed Tyrone McKenna and the voices in my head made me do it.”
She later said that she needed to get her stuff.
“I have a knife in my bag that I used to stab him. My fingerprints will be on it,” she said. “I’m off my medication. That’s why I stabbed Tyrone.”
Sgt Bunn agreed that she had been behaving quite strangely and was ‘erratic’ in her earlier interviews. Mr Burns then read out the memo of her final interview, in which she explained that she had met the deceased in a psychiatric ward in 2010.
The sergeant agreed that she was difficult to follow at times. She made references to being monitored, and to the deceased "being put up to it by politicians and monarchs".
“Most nights, they would make use of spiritual guides,” she said.
She said that stabbing him was "self-defence" from all the "hassle he brought from monarchs from Africa and Ireland".
When brought to court to be charged with murder, she had shouted: “I stabbed that man with full knowledge of what I was doing,” and “No psychiatric assessment.”
He said that she was so agitated that she had to be carried out of the courtroom.
Gardaí searched the house and found a black-handled knife inside a handbag. The sergeant identified the knife in court and said that the DNA profile in the blood on both the knife and tobacco pouch matched that of the deceased.
Professor Aiden Corvin, a consultant psychiatrist attached to St James’ Hospital, then testified on behalf of the defence.
He told Michael O’Higgins SC that he had known Ms Peters as a patient since 2010. She had been diagnosed with schizophrenia, which he described as a "severe, enduring mental disorder".
He said that she had delusional beliefs about the Government, the CIA and MI5 and had believed that she was being tracked by satellites and bugs. He said that at the time of the alleged offence, she was having an acute, severe episode, did not know the nature and quality of the act and wouldn’t have known right from wrong.
He said that she had heard the voice of her dead mother compelling her to commit this act.
“It would have been irresistible at this time,” he said, confirming that she met the criteria required for the special verdict of not guilty by reason of insanity.
Dr Sally Linehan, Consultant forensic psychiatrist at the Central Mental Hospital, testified on behalf of the State.
She told Mr Burns that Ms Peters’ symptoms were most consistent with schizoaffective disorder, the core features of which were psychotic episodes with delusions.
She was also satisfied that she was suffering from a mental disorder at the time of the alleged offence and didn’t understand that what she was doing was wrong.
She said that it had occurred in the context of a severe episode, when she was hearing the voices of her mother and sister.
“She would have felt that her actions were justified and would not truly have understood that they were wrong,” she said.
“Her judgement was so impaired that she was unable to refrain from committing the act.”
She said that she, therefore, fulfilled the criteria for a verdict of not guilty by reason of insanity.
Mr Burns had earlier told the jury that there was no dispute but that Ms Peters had killed Mr McKenna.
“The real question for you is whether she’s entitled to the special verdict of not guilty by reason of insanity,” he said.
He explained that, although the experts for both sides were in agreement, the law required such a verdict to be returned by way of a jury.
The trial continues before Mr Justice Michael White.