OKLAHOMA CITY (AP) - A military appeals court has rejected a request by an Edmond soldier to overturn his conviction for killing an unarmed Iraqi prison detainee in 2008.

In a 3-2 opinion issued on Thursday, the U.S. Court of Appeals for the Armed Forces upheld 1st Lt. Michael Behenna's 2009 conviction for unpremeditated murder in a combat zone. The Edmond soldier is currently serving a 15-year prison sentence at a military prison in Fort Leavenworth, Kan.

Prosecutors say Behenna took a detainee to a secluded railroad culvert and shot him execution-style after interrogating the man at gunpoint about a roadside bombing that killed two men under Behenna's command.

Behenna had maintained the shooting was in self defense and that prosecutors failed to reveal a crime scene expert who supported his claim.