Gardaí found three young children hungry and in dirty clothes and nappies when they called to a house after the children's father claimed he had "killed his wife and kids", the Central Criminal Court has heard.

49-year-old James Kilroy from Westport, Co Mayo has admitted killing his wife, 41-year-old Valerie French Kilroy in June 2019, but has pleaded not guilty to murder by reason of insanity.

Valerie French Kilroy worked as an occupational therapist with Mayo Mental Health services. She was described as an immensely popular woman particularly in the healthcare community, with a wide circle of friends.

By June 2019, she and her husband, James Kilroy, had been married for more than 11 years and had known each other for the previous ten. The court was told there was no history or evidence of domestic violence.

They had three young children and lived in a bungalow in a remote area around six kilometres from Westport.

The court was told Ms French Kilroy was killed at some point between arriving home on the night of 13 June 2019 from a friend's house and the following afternoon when her body was discovered by gardaí.

Garda Leanne Nallen gave evidence that on the morning of 14 June she had found James Kilroy naked and running around a field after receiving a report from a member of the public.

Mr Kilroy was dirty, dishevelled, disorientated and distressed she said. He told gardaí he was on a pilgrimage to Croagh Patrick and God had given him the path to follow.

He was brought to hospital but later that afternoon as he was about to be transferred to the mental health unit, he told Garda Nallen and her colleague that he had a confession. He claimed he had escaped from his home and that he had killed his wife and kids. He said there had been an argument four days previously about him not doing enough.

Garda Nallen told the court they called to the family home and found the couple's children unharmed. However, she said they were wearing dirty clothes and soiled nappies. She noted dirty dishes on the kitchen counter and flower pots knocked over on the floor. The oldest child said their mammy and daddy must have gone to work.

The gardaí changed the children's clothes and one garda went to the shop to buy cereal and snacks for the children. Garda Nallen said it was obvious they were extremely hungry. She became emotional for a brief time as she gave evidence about her interactions with the children.

The body of Ms French Kilroy was found in a camper van on the property. She had been strangled with a ligature and suffered a stab wound to her neck and blunt force trauma to her head.

Detective Sergeant Michael Doherty told the court gardaí had carried out four interviews with Mr Kilroy after his arrest.

In the first, he went into detail about how he had taken drugs throughout his entire life and described a mental health incident in 2001 during which he required inpatient care. In subsequent interviews he demonstrated to gardaí how he had killed his wife. He drew a sketch of the knife he used and described how he had put her in the camper van before walking away. He told gardaí she was still alive when he walked away.

Prosecuting counsel, Anne Marie Lawlor told the jurors Mr Kilroy had accepted he killed his wife and the issue they would have to decide on was his mental state at the time.

She said they would hear expert psychiatric evidence from the defence and the prosecution which they would have to weigh up.

Ms Lawlor said to bring in a verdict of not guilty by reason of insanity, the jurors would have to decide Mr Kilroy was suffering from a mental disorder at the time of the killing, and that he did not understand what he was doing, or did not know it was wrong or could not stop. She said a mental disorder did not include intoxication and that was important in this case.

Ms Lawlor told the jurors it was the prosecution case that Mr Kilroy was simply guilty of murder.

The trial will continue tomorrow.