Lawyers for a soldier accused of killing two superior officers in Iraq asked a judge Friday to force the government to pay for an independent investigator to help them prepare their defense.

Lawyers for Staff Sgt. Alberto Martinez, 39, said Army investigators hadn’t cooperated.

Martinez is the only soldier known to be charged with killing a superior officer during the Iraq war, also known as “fragging.”

He is accused of killing Capt. Phillip Esposito, 30, of Suffern, N.Y., and 1st Lt. Louis Allen, 34, of Milford, Pa., by setting off grenades and a mine in June 2005 in their room at one of Saddam Hussein’s former palaces. They were his superior officers in the 42nd Infantry Division of the New York National Guard.

Military judge Col. Patrick Parrish appeared sympathetic to Martinez, noting that a civilian defendant in a death penalty case could be given an independent investigator at government expense.

“Do you think that would sit will with Congress, knowing that a soldier has fewer rights than a person sitting in a federal prison?” Parrish asked military prosecutor Capt. Adam Siple.

The defense also asked for permission to hire a forensic expert to examine the victims’ computer.