Irish Backpacker Murder In Oz: Guilty Plea A martial arts enthusiast has pleaded guilty in court to killing an Irish backpacker in Melbourne last August. Luke James Wentholt , 31, appeared in the Supreme Court via video link from prison and pleaded guilty to the murder of David Greene. He also pleaded guilty to one count of recklessly causing serious injury to another Irish backpacker, David Byas. Wentholt's then girlfriend, Shayla Pullen, said the group had been having drinks at a hostel in St Kilda, a suburb of Melbourne, on August 26, when an argument broke out. "He wouldn't stop stomping" on the two, she told Melbourne Magistrates' Court. Another witness, Christine Babuczki, who also lived in the house, said Wentholt acted like a "crazy monster." Mr Greene, 30, died in hospital on September 7, almost two weeks after the attack. Mr Byas, 28, suffered serious injuries and was in a coma for four days before being transferred to a rehab facility. Ms Pullen said Wentholt was drunk. She believed he was angry because Mr Greene had joked about accidentally seeing her partially naked earlier that week. "He said, 'Dave, I want to talk to you outside,' in a stern voice," Ms Pullen told the court. Then she heard "smashing noises" and ran up to Wentholt to try and stop him. "They were both bleeding, (blood) was just everywhere," Ms Pullen said. Wentholt trained in jujitsu up to five times a week, she said. Outside court, Australian Irish Welfare Bureau president Marion O'Hagan said Mr Greene's family was suffering. It's been horrific. It's been devastating," she said. Wentholt is due to appear in court again on July 30.