AURORA --The trial began Monday afternoon for one of two men accused of murdering a 6-year-old boy while he slept.It happened in November of 1996 at the home of the boy's grandparents. Prosecutors say 38-year-old Elias Diaz drove the gunman to the home in Aurora. The gunman fired shots into the bedroom where 6-year-old Nicholas 'Nico' Contreras was sleeping. He was killed. Diaz is charged with first-degree murder. He was arrested more than 10 years after the crime. Diaz waived his right to a jury trial. So a bench trial began. Contreras' mother was among those who testified. Prosecutors say the alleged gunman, Mark Downs, fired at the home in retaliation for an earlier shooting.