The plea agreement by Sgt. John Russell of Sherman, Texas, Monday removed the possibility he would receive the death penalty and caps his punishment at life in prison, The (Tacoma, Wash.) News Tribune reported.
In his plea, Russell, 48, said he "wanted the pain to stop" when he shot five service members May 11, 2009, in a combat stress clinic at Camp Liberty in Baghdad.
The military judge, Col. David Conn, accepted the agreement after he questioned Russell for several hours, but the plea does not end the case. Prosecutors want Russell to admit the shootings were premeditated. Russell has refused, saying he was suffering from severe depression and post-traumatic stress disorder.
The court will reconvene May 6 to consider the issue.
Pistorius testifies he didn't consciously pull trigger when he shot girlfriend
'Happy' fan videos make Pharrell cry [VIDEO]