Woman deemed unfit to stand trial for murder of man

Mercy Peters accused of killing Tyrone McKenna at house in Rathfarnham in 2014

A 44-year-old woman with schizophrenia has been deemed unfit to stand trial for the murder of a man in his South Dublin home in 2014.

Mercy Peters, originally from Sierra Leone, is charged with murdering Tyrone McKenna (42) on July 17th, 2014 at the house they had shared in Marley Court, Rathfarnham, Dublin 14.

At a Central Criminal Court hearing on Wednesday, Mr Justice Tony Hunt heard there was an issue to be decided by him about Ms Peters fitness to stand trial.

Paul Burns SC, prosecuting, called a consultant forensic psychiatrist from the Central Mental Hospital (CMH) to give evidence on the issue.


Dr Sally Linehan said she interviewed Ms Peters on two occasions in order to give her opinion regarding her fitness to be tried and had prepared two reports on each assessment.

The witness said she was first asked to meet Ms Peters on June 9th, 2016 and reviewed her history.

Dr Linehan said Ms Peters has been in the CMH since July 21th, 2014 and the accused did not agree with her diagnosis that she had a mental disorder. The accused told Dr Linehan that she had never heard voices or had hallucinations. She also denied any feelings of being controlled by an external force.

Persecutory themes

The court heard Ms Peters had persecutory themes involving the gardaí and Dr Linehan formed the opinion that her insight into her illness was “very poor”.

The witness said she came to the conclusion that Ms Peters had a mental disorder at the time of the offence and was suffering from paranoid schizophrenia. She said her illness displayed entrenched persecutory and delusional themes.

Concerning her fitness to be tried, Dr Linehan said Ms Peters had incorporated the criminal proceedings into this delusional system. She would be unable to make a proper defence and her capacity to give instruction to counsel would be impaired, said the witness.

Dr Linehan said she further assessed the accused on June 1st, 2017 and compiled a second report. The witness again formed the opinion that Ms Peters insight into her mental health issues was limited and her mental state was unchanged. She said in addition to her delusions, Ms Peters presented with mood disturbance.

The witness said she remained satisfied when she reviewed Ms Peters again on June 1st that she met the criteria of a mental disorder. However, Dr Linehan said her opinion of the accused’s diagnosis had changed and diagnosed her as having a schizoaffective disorder.

She said it remained her opinion that Ms Peters did not satisfy the criteria for fitness to be tried as her reasoning and judgement was so impaired by her illness that she would be unable to meaningfully instruct a legal representative.

Very intelligent

Under cross-examination by Michael O’Higgins SC, defending, Dr Linehan agreed that Ms Peters had not been taking her prescribed medication for several months before this event occurred.

The court heard Ms Peters had received a very good education in Sierra Leone where she worked as a journalist. Mr O’Higgins said his client - who is a “very intelligent and articulate woman” - came to Ireland where she was involved in various organisations assisting asylum-seekers.

Dr Linehan agreed with counsel that Ms Peters’s overarching view was blocked because of “this persistent delusional belief system” concerning gardaí­, MI5 and how Mr McKenna had a death wish.

“The core element of her illness is a series of delusional beliefs with persecutory themes,” she confirmed.

The defence then called Dr Aiden Corvin, Professor in Psychiatry at Trinity College, to give evidence.

Dr Corvin said he had been Ms Peters’s treating psychiatrist for several years and had diagnosed her with schizophrenia. He said despite Ms Peters being treated and medicated over the last three years, her “belief system” was still entrenched.

The witness concluded that, arising out of Ms Peters’s long-standing delusional beliefs and the fact that her judgement and reasoning were impaired by her mental disorder, she was unable for the judicial process.

Mr Justice Hunt said it was “quite clear” that the evidence in this “very tragic” case had proved that the accused was suffering from a “chronic” mental disorder.

“It must be said from the outset that what is an unusual feature of the evidence is that Ms Peters is a very intelligent person with an understanding of the criminal process which goes beyond what one would expect in a lay person,” he said.

The judge said that the strength of the accused’s delusional beliefs were so strong that she was unfit to be tried.

Mr Justice Hunt then made an order committing Ms Peters to the Central Mental Hospital until July 21st. He also directed the preparation of a psychiatric assessment by an approved medical officer.