The trial heard that Shane Smyth, aged 29, believed Mairead Moran had stolen a “vile of his blood”, had “installed hidden cameras”, and put “black widow spiders” in his house.
Mr Smyth, of McGuinness House, Evans Lane, Kilkenny, was charged with murdering Ms Moran, aged 26, on May 8, 2014 at the Market Cross Shopping Centre in Kilkenny City.
Last week at the Central Criminal Court, Mr Smyth pleaded not guilty to murdering Ms Moran by reason of insanity.
The jury had been told that the facts of the case were not disputed.
Last week forensic psychiatrist Dr Brenda Wright gave evidence that Mr Smyth was suffering from severe paranoid schizophrenia at the time.
A second forensic psychiatrist, Dr Paul O’Connell, from the Central Mental Hospital, also gave evidence that the accused was suffering from schizophrenia and was “not capable of forming a specific intent”.
In her charge to the jury yesterday, Ms Justice Margaret Heneghan said there were three possible verdicts open to it in this case, but that the verdict of “not guilty by reason of insanity” would be in accordance with the lengthy evidence they had heard in the case.
“The law requires that you must make a finding of fact in this case and a verdict other than the verdict of not guilty of murder by reason of insanity means you would be rejecting the evidence of the two psychiatrists,” said the judge.
Finishing her charge, Ms Justice Heneghan said the “evidence in this case all points one way”.
The jury, comprising three men and nine women, spent 55 minutes deliberating before bringing in a unanimous verdict of not guilty of murder by reason of insanity.
After they had delivered their verdict, the judge thanked the 12 jurors for their time as they had been longer in court “than anticipated” and excused them from jury service for the rest of their lives.
Ms Justice Heneghan, addressing the jury, said: “You have performed a critical task.
“It has been a difficult trial and some of the elements were extremely upsetting and disturbing.
“It is a difficult duty you have carried out and I thank you for the attention you have given this trial.”
At the request of John O’Kelly, prosecuting, Ms Justice Heneghan ordered that Mr Smyth be detained in the Central Mental Hospital and put in the matter for mention on February 15.
Finally, the judge told the court that at the commencement of the case she had asked for the co-operation of everyone, which, she added, she had received at all times.
“There are two families involved and I can only extend my sympathy and those of the registrar to Mairead Moran’s family,” said Ms Justice Heneghan.
“It has also been a difficult trial for members of the Smyth family and I thank that family for having behaved as to how I asked them to in court.”