THE boyfriend of a 19-year-old woman charged with murdering her brother said she told him she was taking a steak knife to a party because she needed "protection", a trial has heard.
The victim struck his sister across the face moments before he "slumped to the ground", a jury at the Central Criminal Court in Waterford heard.
The trial of Caroline Brennan for the murder of Michael Brennan (22) at a party in their uncle's house heard Mr Brennan also "punched" his girlfriend Lisa "to the ground" that night.
It also heard that Mr Brennan was "out of control" on drunk and drugs and threatened to "smash in" his girlfriend's head.
Mr Brennan died from a single stab wound to the heart at Barrack, Street, Castlecomer, Co Kilkenny, shortly after 3.30am on December, 30, 2008.
Caroline Brennan, of Love Lane, Castlecomer, has denied murdering her brother.
The court heard Brennan had taken a steak knife from her house to go to the party at around 1am, where her brother had been drinking and taking drugs with friends since the previous afternoon.
Brennan's boyfriend Keith Byrne told the court that Caroline had told him: "Michael is going to start trouble tonight," and that she needed the knife for "protection".
Mr Byrne said when they arrived, Mr Brennan told him he was taking heroin. An argument broke out between Caroline and Mr Brennan because he was using the drug.
He said they wanted to get out, so they left and were in Mr Byrne's car when they heard a scream from the house and saw Mr Brennan punching his girlfriend, Lisa Peagram, to the ground outside the front door.
Ms Peagram told the court: "Michael boxed me and pushed me out the door". In cross-examination by Paddy McCarthy, Ms Peagram said that when Mr Brennan was drinking he "could easily snap and be violent".
The court heard that Thomas Timmons, who was at the party, had told gardai he saw Caroline Brennan with "a knife in her right hand at hip level" and that "she stuck the knife in Michael Brennan".
The trial continues.