A 29-year-old man who stabbed his ex-girlfriend to death in May 2014 has been found not guilty of murder by reason of insanity.

Shane Smyth, from McGuinness House, Evans Lane, Kilkenny, has pleaded not guilty by reason of insanity to murdering 26-year-old Mairead Moran on 8 May, 2014.

He was suffering from paranoid schizophrenia when he stabbed Ms Moran several times at the Market Cross Shopping Centre where she worked.

The trial heard he was hospitalised for two weeks in 2006 but his condition went untreated in subsequent years until the death of Ms Moran in 2014.

He had been suffering from psychosis and delusions and believed she was involved in a conspiracy against him and wanted to steal his blood.

Ms Moran had dated Mr Smyth seven years previously but had lost contact with him after she moved away.

In the weeks leading up to her death, she had complained that he was hanging around the shop where she worked and had accused her of working for a company that had kidnapped him and stole his blood.

On 8 May, 2014, he had been told by a security guard to leave the shopping centre after upsetting Ms Moran while she worked in the Holland and Barrett health store.

However, he returned minutes later with a knife and stabbed her a number of times after dragging her outside the shop.

Two psychiatrists who gave evidence during the five-day trial said Mr Smyth was suffering from a mental disorder and was incapable of forming the intent to commit murder.

They also said he was not in control of his actions at the time.

After deliberating for less than an hour the jury found him not guilty of murder by reason of insanity.

Ms Justice Margaret Heneghan thanked the jury for their work in what had been a very difficult and distressing case. She excused them from jury duty for life.

Mr Smyth will be detained at the Central Mental Hospital for psychiatric assessment by order of the court. He will be brought back before the court in two weeks' time.

In closing arguments, defence counsel Colman Cody told the members of the jury they may have asked themselves at the outset of the trial how could this have happened.

"You might ask how could a young, vibrant girl with her whole life ahead of her had her life ended so abruptly and violently? You might ask how can he admit doing the physical act and yet not be held responsible in law?"

He said words such as "schizo, mad, crazy" were used perhaps jovially by people but they had real and specific meaning and had clinical and precise meaning to describe conditions that could have life-altering and devastating circumstances, not just for those with the condition but for innocent third parties.

Mr Cody said they were dealing with the shocking tragedy, the horror and unimaginable grief of the victim's family but if there was something positive to take from it, perhaps it was that their understanding of mental illness, particularly paranoid schizophrenia, may have been enhanced by the evidence.

He said the evidence of two psychiatrists with years of experience was that he did not have the capacity to form the intent to commit murder and that his actions were a direct consequence of an enduring illness going back many years.

He said it was based on hard evidence and not theorising.

He said it was natural and understandable to have the utmost sympathy for the Moran family who had lost a daughter and a sister.

He said Smyth family had also lost a son and a brother but they would be able to see him and speak to him, whereas the Morans could not do that with Mairead.

Mr Cody said the jury would have to decide the case in a clinical and dispassionate manner and the evidence points in one direction.

He said by returning the special verdict of not guilty by reason of insanity they would not be disparaging the memory of Mairead Moran, nor would they be allowing him to walk free, to return to the streets or main stream society.

Mr Cody said it was quite the contrary, they would be ensuring he remains in hospital for the correct long-term treatment and thereby protect "society so that a shocking tragedy such as this may be prevented into the future".

Prosecuting counsel John O’Kelly also reminded the jury that both psychiatrists gave clear evidence that on the day of the attack, Mr Smyth was incapable of forming the necessary intent for murder.

He said it was a difficult and tragic case but the jury was in a fortunate position that it had a volume of evidence to assist it in coming to a fair and just verdict.

In her charge to the jury, Judge Heneghan said the accused man does not get to walk out the door, he goes back to the Central Mental Hospital and in two weeks he would be brought back before the court and the judge would decide what is to happen to him.

The jury had heard evidence that there was a very extensive treatment plan proposed.

She explained to the jury that if it found that Mr Smyth was suffering from a mental disorder the law says it "shall" return a verdict of not guilty by reason of insanity.

She said two psychiatrists had given evidence that Mr Smyth suffered from a mental disorder and if they accepted this evidence it was mandatory they return the verdict of not guilty by reason of insanity.