A 21-year-old an accused of murdering his 17 year-old sister told gardaí he didn't know why he killed her and that he loved her, a jury at the Central Criminal Court has heard.
Patrick O'Dwyer, then aged 19, of Shrohill, Ennistymon, Co Clare, has pleaded not guilty to murdering his sister Marguerite, at the family home on November 29th 2004.
The court heard that during garda interviews Mr Fahy admitted killing his sister by 'belting' her on the head with a hammer and then stabbing her with a knife and scissors.
Mr O'Dwyer told gardaí that on the day of the killing- a Monday- he bought two cans of Red Bull and two packets of paracetemol on his way back from his job as a butcher's apprentice.
He said his parents were away on holidays and that he still had a headache on the Monday following a drunken fall on the Saturday night when his sister had a party in the house.
He claimed he had around eight paracetemol on the day of the killing. He spent the evening of the killing watching TV with his sister. He said halfway through a television programme he went into the kitchen and picked up a hammer from the press.
He told gardaí he was annoyed because he had made a fool of himself on the Saturday by getting sick and falling after drinking too much and that he intended to hurt himself with it.
Instead, he said he walked into the sitting room and approached Marguerite. He said she must have thought he was joking because she looked up and smiled at him.
"I'd often be messing with a hurley and things," he said. He said he then hit her across the head with the hammer and paused before striking her a few more times.
Mr O'Dwyer said his sister never screamed because the first "belt did enough damage". After she fell to the floor, he said she was still alive and that he picked up a scissors and a knife from the kitchen. He admitted 'jabbing her' in the torso and legs to make sure she was dead, before going outside to smoke and walk. When he returned, he said he drank half a can of beer in front of the TV and threw a blanket from the couch on her body.
He said he loved her and that he regretted her death because she had a "great life" ahead of her.
"I just can't explain why I did what I did," the court heard he told gardaí.
In his opening for the prosecution, John Edwards SC said the main issue in the case was whether the accused was suffering from a mental disorder at the time of the incident.
He told the jury that the defence would be basing their case on the defence of diminished responsibility.
He said that if they accepted the accused was suffering from a mental disorder, they would have to find him not guilty of murder but guilty of manslaughter, but that they first had to decide on other issues in the case.
The trial before Mr Justice Paul Carney continues tomorrow.