U.S. Army Staff Sgt. Robert Bales was sentenced to life in prison without the possibility of parole Friday. He pleaded guilty in June to killing of 16 Afghan civilians in March 2012.
Bales was spared the death penalty as part of a plea agreement.
The mass killing of the villagers -- mostly women and children -- is the worst case of civilian slaughter blamed on a single, rogue U.S. soldier since the Vietnam War. The incident further strained relations between the United States and Afghanistan after more than a decade of U.S. involvement in the country.
Bales was on his fourth combat deployment when the killings took place. He had been drinking and watching a movie with other soldiers at Camp Belambay in Kandahar province. Just before dawn, Bales slipped away, armed with a 9-mm pistol and an M-4 rifle, and killed 16 civilians in the village of Alkozai, the court was told.
He returned to base, woke another soldier and told him what happened. But the soldier didn't believe Bales and went back to sleep. Bales left again to attack a second village, Najiban.
The massacre sparked angry protests in Afghanistan, causing the U.S. to temporarily halt combat operations in the country. Meanwhile, it took three weeks before Army investigators could reach the crime scene.
Prosecutors in the case said Bates was familiar with the villages he attacked and knew that women and children lived in the homes he invaded. They questioned how remorseful Bales truly felt, playing for the jury a recording of a phone conversation with his wife in which he laughs as he recalls that the Army cut the number of murders he was charged with down to 16, from 17.
"At least they dropped one count of murder," he said.
Bales, 39, testified during the sentencing hearing that the killings were "an act of cowardice, behind a mask of fear, bull---- and bravado." He apologized for his actions and said he regularly drank alcohol and used sleeping pills and admitted he drank a great deal of alcohol on the day of the massacre.
"I'm truly, truly sorry to those people whose families got taken away," Bales told the jury in a military courtroom in Seattle. "If I could bring their family members back, I would in a heartbeat."
The sentencing hearing gave some of Bales' victims the chance to face him in court.
Haji Mohammad Naim, an Afghan farmer who was shot by Bales during the massacre in Kandahar province, cursed Bales in the courtroom before breaking down and pleading with the prosecutor not to ask him any more questions.
"This bastard stood right in front of me," the farmer said, testifying through an interpreter. "I wanted to ask him, 'What did I do? What have I done to you?' ... And he shot me!"
Seven Afghans testified -- four who had been hurt in the attacks and three others who were relatives of the dead or wounded.
Bales' defense lawyers, who declined to cross-examine any of the witnesses, sought to show that he suffered a mental breakdown during his fourth and final deployment to Afghanistan. They argued that he suffered from post-traumatic stress disorder and a brain injury before his final deployment.
"I don't think anybody with a rational mind could say Bob Bales didn't snap," defense attorney John Henry Browne told reporters on Wednesday after a court-martial session before a military jury.
Lt. Col. Jay Morse offered the most detailed single account yet of the attack, recounting the killings compound by compound and room by room, describing at one point how a widow was left clutching bits of her husband's skull after the killer finally left. Bales looked away as prosecutors displayed pictures of some of his bloodied victims.
At the time, Bales was under heavy personal, professional and financial stress, Morse said.
"The accused felt inadequate as a soldier and as a man because of his personal, financial and professional problems," Morse said.
Furthermore, Bales had expressed a desire for revenge after a fellow soldier stepped on a roadside bomb and lost his leg below the knee a week earlier -- though Bales did not witness the event or see the soldier afterward, Morse said.
Al Jazeera and wire services