The Los Angeles Times reported Staff Sgt. Justin Laughner was the first witness to indicate evidence in the killings at Haditha may have been covered up.

Laughner testified under immunity Lt. Andrew Grayson ordered him to delete the photos of Iraqi women and children killed by Marines in 2005 from his computer. He said he lied later when he was asked if photos had been taken at the scene of the deaths of 24 civilians.

"It was wrong," Laughner said. "Somebody was asking for (the photos) and we're not going to give them to them? It's not right, but I didn't say anything."

Grayson has been charged with dereliction of duty and obstruction of justice.

Three other officers are charged with dereliction of duty for not calling for a war-crimes investigation into the killings.

Laughner testified at the military equivalent of a pretrial hearing he had no evidence battalion commander Lt. Col. Jeffrey Chessani knew of the existence of the photos, the Times reported.