Bales was led away from the court without a chance to hug his wife or mother after the verdict was announced in a courtroom at Joint Base Lewis-McChord in Washington state, The Tacoma News-Tribune reported.
In June, Bales, 40, pleaded guilty to murder, which carries a mandatory minimum life sentence under the Uniform Code of Military Justice. At issue is whether the military jury would grant him the opportunity for parole.
Bales Thursday apologized for the slaughter, saying he had no explanation for the dozen killings but that he grieved for the lives he ruined. Attorney Emma Scanlan said his taking responsibility for the deaths should have been taken into account when considering whether Bales should be eligible for parole.
The military jurors were presented with two portrayals of Bales during closing arguments Friday: one as a cold-blooded killer and the other as a respected non-commissioned officer who "snapped," the News-Tribune said.
"The truth is Sergeant Bales is a man of no moral compass with no one to blame and nothing to blame but himself," Army prosecutor Lt. Col. Jay Morse said.
"I believe he was finally overwhelmed by witnessing the deaths and injuries of the soldiers he loved so much," one of Bales' former officers wrote in a letter his defense attorney read to jurors. "It wears you down. While many of us are able to handle it a little better, for Sergeant Bales, each time it got worse and worse."