Capt. Phillip T. Esposito and 1st Lt. Louis E. Allen died about 10 p.m. Tuesday at Forward Operating Base Danger, near Tikrit, and the military said then that "an indirect fire attack" killed them.
"The initial investigation by responders and military police indicated that a mortar round struck the window on the side of the building where Esposito and Allen were located at the time," a military statement said.
"Upon further examination of the scene by explosive ordnance personnel, it was determined the blast pattern was inconsistent with a mortar attack," the document states.
The Army is looking at a number of scenarios including accidental death, attack by an intruder or infiltrator and fragging, which is the killing or wounding of a fellow soldier.
Both officers were "assigned to Headquarters & Headquarters Company, 42nd Infantry Division, New York Army National Guard. Esposito was the company commander; Allen served as a company operations officer," the statement reads.
