He is accused of the murder of Thea Kheav, 21, at an 18th birthday party in Parafield Gardens, in Adelaide's north, in December 2007. Prosecutor Kos Lesses said the accused was part of a group of men at the party who argued with one of Mr Kheav's brothers. "It's about a group attack on Thea Kheav allegedly committed by these four men," Mr Lesses said. "The issue in this trial … is going to be one of involvement and group criminal responsibility," Mr Lesses said. "What is in dispute is this idea that he is a murderer, so that's where the battle lines are drawn," he said.