The trial of a 29-year-old man for the murder of his former girlfriend in May 2014 has heard he had suffered from a psychotic illness which remained untreated for years before she was stabbed to death.

Shane Smyth, of McGuinness House, Evans Lane, Kilkenny, has pleaded not guilty at the Central Criminal Court by reason of insanity to murdering 26-year-old Mairead Moran on 8 May 2014 at the Market Cross Shopping Centre in Kilkenny city.

Ms Moran was stabbed repeatedly in what was described as a terrible attack, during which she was stabbed in the heart.

Prosecuting counsel John O’Kelly told the jury a lot of the facts of the case would not be in dispute and the major factor in the case would be whether or not Mr Smyth was suffering from a mental disorder at the time.

He said two consultant psychiatrists had prepared reports indicating that Mr Smyth was suffering from a form of psychosis and delusions at the time of the attack.

Mr O'Kelly said Ms Moran was working in the Holland and Barrett shop at Market Cross Shopping Centre and was on the late shift.

She and the accused had gone out together years previously for seven months but went their separate ways.

Ms Moran had moved away from the area for a time and had gone to college and then returned to the area.

Mr Smyth had been diagnosed in 2005 with schizophrenia and had spent a number of months in hospital being treated before returning back into the community. 

They had seldom met or even come across each other during that period but in the months leading up to the incident he had become aware of where she was working and there had been an occasion where he had confronted her and had spat at her, which had upset and disturbed her.

On 8 May 2014 he had come into the shop and started speaking to her quite aggressively and people overheard him asking her: "Why did you want my blood?"

He was ordered to leave by a security guard but returned about five minutes later when "a terrible attack" took place and Ms Moran was attacked with a knife and dragged outside and stabbed repeatedly.

Mr Smyth was told by onlookers to drop the knife which he did and he was placed sitting on the floor while Ms Moran was tended to.

He then "hopped up" and ran from the shopping centre and took a taxi to his cousin's house and told his cousin he had stabbed his ex-girlfriend.

Gardaí were called and he was arrested and gave a number of interviews.

The jury was told a report had been prepared by a Dr Paul O'Connell who said the accused man was suffering from paranoid schizophrenia which had its onset in adolescence and had been untreated from 2006 until his arrest and admission to hospital following the tragic death of Ms Moran.

Dr O'Connell said Mr Smyth remained mentally ill and exhibited active symptoms of psychosis. He had delusions about his interaction with Ms Moran and failed to appreciate the enormity of his actions.

His behaviour at the time was driven by his symptoms and his judgement would have been "grossly impaired" according to the report, which added that he would have been unable to refrain from his actions.

Defendant believed victim was part of conspiracy, court told

A second consultant psychiatrist, Dr Brenda Wright, had also prepared a report which said he did not have the capacity to form intent as a result of his mental disorder, and in her opinion he did not understand the nature and quality of the event.

Dr Wright said he believed he was being persecuted and that people were conspiring to harm him and that Ms Moran was part of that conspiracy.

She also said he delusionally believed he was being victimised and harboured psychotic moral justification and was unable to refrain from acting in the way he did.

These episodes appeared to have occurred in the context of his psychotic illness.

The jury was told that under the Criminal Law Insanity Act of 2006 it was open to a person to plead not guilty by reason of insanity.

Mr O'Kelly said where an accused person is tried for an offence and the jury finds the accused person committed the act, and having heard evidence relating to his mental condition, finds that he was suffering at the time from a mental disorder and ought not to be held responsible because he did not know the nature and quality of the act, did not know what they were doing was wrong or was unable to refrain from doing the act, the jury could return a special verdict of not guilty by reason of insanity.

Security guard James Coffey who was working in the shopping centre, described how he had told Mr Smyth to leave the shopping centre after he observed him upsetting Ms Moran and accusing her of "working for a company who kidnapped him and stole his blood".

He said Ms Moran told him Mr Smyth had done the same thing on a previous occasion.

She told him who Mr Smyth was and told him that he had been a psychiatric patient and was obviously "off his meds".

Mr Coffey said he told Mr Smyth to leave and made sure he left after an altercation during which he had kicked out at him and grabbed his radio when he tried to call for assistance.

He informed a colleague of what had happened and passed on Mr Smyth's name to his colleague. Minutes later he got a call on his radio simply to tell him "Holland and Barrett". 

When he got there he at first thought Mr Smyth had hit Ms Moran and he stood between them but then saw a knife in his hand and got him to drop it.

He said Mr Smyth had a completely blank expression on his face. "He had a stone faced look, I've never seen anything like it before".

When he turned his attention to Ms Moran, Mr Smyth got up and ran off. He had tried to chase him but slipped.

Another witness Angela Hennessey said she had seen Mr Smyth shouting and using language at the security guard before leaving the shopping centre "in a huff".

She had put her shopping in her car and returned to the centre a few minutes later and then saw Ms Moran lying on the ground in front of the shop.

Another witness, Eimear Lawlor, described how she saw the accused man dragging Ms Moran by the hair outside the shop and stabbing her a number of times in the chest as she screamed.

She said Ms Moran put her hand to her head and screamed even more when she saw the blood. She then saw a security guard intervene and another on a phone.

The trial continues.