Curtis James Hill, 29, faces life in prison without the possibility of parole. His sentencing is scheduled Dec. 16.
Hill and his co-defendant, John Kirk McKinney, 29, also a Huntington Beach resident, beat up 77-year-old Cecil Warren on Nov. 11, 2003, after he noticed them inside his parked van, according to prosecutors. Warren, working at the time as a handyman, was cleaning the parking lot of a bank in Huntington Beach.
The veteran spent almost four years in a coma before dying from injures he sustained during the beating, prosecutors said.
Hill and McKinney had been in jail since 2006, serving time for the beating, and were expected to be released this year, but were charged with murder Sept. 4, 2009.
McKinney faces the same charges and sentence as Hill and his trial is scheduled on Feb. 27.