Woman found not guilty by reason of insanity of murdering flatmate

Mercy Peters told gardaí that voices in her head made her stab Tyrone McKenna

Mercy Peters. Photograph: Frank Miller

Mercy Peters. Photograph: Frank Miller


A 46-year-old former journalist has been found not guilty by reason of insanity of murdering her flatmate in their south Dublin home.

Mercy Peters had told gardaí that voices in her head made her stab the 42-year-old.

The Sierra Leone native went on trial at the Central Criminal Court on Tuesday, charged with murdering Tyrone McKenna on July 17th, 2014 at the house they had shared in Marlay Court, Rathfarnham. She pleaded guilty by reason of insanity.

The trial heard that both the accused and deceased had a history of mental health problems and had first met in a psychiatric ward in 2010. They became friends and were living with Mr McKenna’s father, Tom McKenna, at the time of the killing.

Tom McKenna went out for a walk that Thursday afternoon, returning home to find his son lying on his back at the bottom of the stairs. He appeared motionless.

Mr McKenna went 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.

Tyrone McKenna had no pulse when the ambulance crew arrived, and he was pronounced dead at the scene.

A post-mortem examination later gave the cause of death as a stab wound to the trunk, which collapsed his left lung and injured his 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.

Gardaí found Mercy Peters 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 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 a hotel room for her. However, she didn’t want to go and requested to stay in the station overnight.

A garda noticed her talking to herself and counting on her fingers the following morning. She said she was talking to her spirits.

She again declined the offer of accommodation before telling another garda 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.”

The court heard that she behaved quite strangely and was “erratic” in her interviews, and 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 shouted: “I stabbed that man with full knowledge of what I was doing,” and “No psychiatric assessment.”

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 DNA profile in the blood on both the knife and tobacco pouch matched that of the deceased.

Prof Aiden Corvin, a consultant psychiatrist attached to St James’s Hospital, testified on behalf of the defence.

He said that 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.

Paul Burns SC, prosecuting, told the jury on Wednesday that it was not disputed that Peters had killed the deceased. He said that the issue for the jury was whether she met the criteria for the special verdict to which she had pleaded.

“If you come to the conclusion on the balance of probabilities that she does, then the verdict you should return is not guilty by reason of insanity,” he said.

Michael O’Higgins SC, defending, said his client was from “a high-achieving family”. The court had already heard she had worked as a journalist with a daily newspaper in Freetown.

Mr O’Higgins noted in his closing speech that the family had fled Sierra Leone during the war and that she had came to Ireland as a refugee.

“She was integrating herself into this society, working closely with other refugees,” he said, referring to her roles with a number of organisations.

He noted that she had become very ill mentally in 2009 and had been diagnosed with a schizophrenic-type illness by 2011.

It was managed with a medication regime. “She wasn’t a danger to herself or anyone else, providing that regime was kept up,” he continued. “There were times when that regime was not kept up, including on this occasion. When the medication is not taken, the illness tends to manifest itself, in this case in a very, very severe form.”

“She was full of delusions and there was this complex persecutory situation in which she had a fixed, false basis for believing certain things, which people in the full of their mental health would never conceive.” He said that this had, tragically, resulted in Mr McKenna being stabbed.

Following 23 minutes of deliberations, the jury of eight men and two women returned with a unanimous verdict of not guilty by reason of insanity.

Mr Justice Michael White thanked the jury and expressed the court’s deepest sympathy to Mr McKenna’s family.

He committed Mercy Peters to the CMH. He adjourned the case to May 21st for an examination of her there and preparation of a report for court.