U.S. Army Sgt. Robert Bales could face up to life in prison during the sentencing phase of his trial after pleading guilty to murdering 16 Afghan civilians. Bales is set to be sentenced Monday at Joint Base Lewis-McChord court in Washington state, CNN reported. Prosecutors agreed not to seek the death penalty in return for his guilty plea to the March 2012 killings. A military panel of four officers and two elicited personnel will decide if Bales, 39, should ever be given a chance for parole. Bales\' attorneys have said he suffered from post traumatic stress syndrome and brain injury after four tours of combat and had been using drugs and alcohol the night of he made raids on family compounds in Kandahar province. Prosecutors have said Bales was upset about an explosion near his outpost and the attacks were his response. In addition to the 16 murder counts, Bales pleaded guilty to six counts of attempted murder, seven of assault and the use of illicit steroids and alcohol. He pleaded not guilty to obstruction of justice.