Jurors will hear differing evidence from expert psychiatrists for the prosecution and defence in the trial of a man accused of murdering three members of his family in their Co Louth home last year, the Central Criminal Court was told.
Robert O’Connor (32), of Drumgowna, Louth Village, Dundalk, Co Louth, pleaded not guilty of murder by reason of insanity, or guilty of manslaughter on the basis of diminished responsibility to the triple murder of his mother Louise O’Connor (56), his father Mark O’Connor (54) and his younger brother Evan O’Connor (27) at their home in Drumgowna between September 28th and 29th 2025.
In her opening address on Tuesday, prosecution counsel Roisin Lacey SC said the jury will hear evidence that Robert O’Connor had episodes of psychosis from a young age and was diagnosed with schizophrenia in 2018.
Counsel said the special verdict of not guilty by reason of insanity is not one that a psychiatrist engaged on behalf of the prosecution would support.
Whereas the defence position is that the accused does come within the criteria of the Criminal Law Insanity Act 2006, she said.
The jury panel also heard the prosecution psychiatrist will give evidence that the accused’s mental disorder of schizophrenia had substantially diminished his responsibility for the three killings.
Prosecution counsel previously told the jury that O’Connor accepted he caused the death of the three victims in the case.
The jurors have already been told they will hear evidence that the three victims sustained a combined 139 stab wounds. Last week in her opening address, Lacey said that the accused told gardaí that he had a row over drugs, lost his head and only meant to kill his father and brother, but not his mother.
Lacey told Judge Mícheál P O’Higgins and the jury of six men and six women that they would hear from forensic scientist Georgina Daly, who examined a number of items taken from Drumgowna.
Counsel said Daly examined two knives, the accused’s clothing and door handles from inside and outside the patio door area.
Lacey said forensic scientist Andrea McGrath examined a three-seater couch in the sittingroom, which had a considerable amount of blood-staining.
McGrath, counsel said, will tell the jury that blood-pooling on three areas of the sittingroom floor and on a two-seater couch matched Mark O’Connor. The lawyer said McGrath found that Mark was actively bleeding in those areas while he was in an upright position.
Lacey said the jury will also hear psychiatric evidence during the trial, which will be “critical”. The barrister said in this case, the issue of the intention for murder must be interpreted in the context of psychiatric evidence.
Lacey said there will be evidence from two expert psychiatrists; Dr Fiona Toal engaged on behalf of the defence and Dr Ronan Mullaney engaged by the prosecution.
The barrister further stated that the jurors have already heard the two pleas put forward by the accused; “not guilty by reason of insanity or the alternative plea of guilty of manslaughter by reason of diminished responsibility”.
The three criteria for a verdict of not guilty by reason of insanity under the Criminal Law Insanity Act 2006 are that an accused did not know the nature and quality of the act, or was unable to appreciate that what they did at the time was wrong or would have been unable to refrain from their actions.
Counsel said the court will hear that Toal is of the view that the accused “does come” within the second two criteria of the Act; namely that he didn’t know what he was doing was wrong or was unable to refrain from committing the act.
Counsel said the prosecution’s position is that Mullaney disagrees with Toal. She said Mullaney accepts that the accused was in a state of psychosis and was having a psychosis relapse of schizophrenia. “Mullaney does say, like Toal, that Robert O’Connor did know the nature and quality of the act, where he disagrees is in relation to the two other elements; that he didn’t know what he was doing was wrong or was unable to refrain.”
The barrister said the court will also hear evidence from Mullaney that the accused’s ability to regulate his conduct was substantially impaired, but not fully impaired. Lacey said the special verdict of not guilty by reason of insanity is not a verdict Mullaney would support from a psychiatric point of view. The barrister said the alternative plea entered by the accused is guilty of manslaughter by diminished responsibility.
She said legislators had provided for this in section six of the Criminal Law Insanity Act 2006 and that this was the second potential verdict open to the panel. “Diminished responsibility is where a mental disorder is operating at the time of the killing and you will hear evidence that the person is criminally responsible but it is substantially diminished.”
Lacey said Mullaney will give evidence on behalf of the prosecution that on the balance of probabilities, the accused was suffering from schizophrenia at the material time and that his mental disorder substantially diminished his responsibility for each of the three killings.
Essentially, she explained, the “battleground” between the prosecution and defence is the verdict of not guilty by reason of insanity. The trial continues on Thursday.