Bales had been downing Jack Daniels whiskey on a rural base 22 miles west of Kandahar when he allegedly left the installation and walked to the first of two neighboring villages, killing unarmed civilians as he went from dwelling to dwelling, prosecutors said at a pretrial hearing at Joint Base Lewis-McChord, Wash., to determine if Bales will face a full court-martial and potentially the death penalty, NPR reported.
The alleged massacre occurred in the villages of Balandi and Alkozai in Afghanistan's Panjwayi district, which is known as the birthplace of the Taliban.
A key witness said Bales was covered in blood when he returned to the base and said, "It's bad, it's really bad."
Prosecutors allege Bales returned to the base and told another soldier he'd just killed several people. That soldier thought Bales was joking and did not restrain him, prosecutors said. Bales then allegedly went off the base again and killed more people. By the time his rampage was over, 16 Afghan civilians were killed and six more were wounded. Nine were children and 11 were from the same family.
Military investigators for the first time showed a video from a surveillance blimp showing the sergeant returning to the base, putting down his weapon and surrendering, NPR said.
Bales' wife maintained her husband's innocence as prosecutors laid out a horrific sequence of events.
"My husband did not do this -- did not do this," Kari Bales told ABC News before the hearing. "I truly believe, from the bottom of my heart, that my husband is not involved."
She said it was "incomprehensible" to her that her husband faced 16 charges of premeditated murder. He also faces six counts of assault and attempted murder for six others who were wounded and charges of alcohol consumption and using an illegal anabolic steroid commonly used by athletes to build muscle mass.
The 38-year-old Army veteran was serving his fourth combat tour in Afghanistan after three stints in Iraq.
Bales -- the youngest of five boys who grew up in Norwood, Ohio, a suburb of Cincinnati -- was formally charged in the killings March 23.
"It doesn't seem possible, especially that there were women and children," Karilyn Bales said. "My heart goes out to those families that lost loved ones, parents and grandparents. I am a mom. I can't imagine losing my child, especially to something like that."
She said her husband didn't fully know what happened when he called her after the incident.
"He was like: 'What? What you talking about?' ... He knew that something was going on, but did not know the extent of what was going on, and I was actually the one that had told him how many people had died, and that included women and children, and he was blown away. He did not know the details as they had been portrayed in the press."
Parts of the hearing, which could last up to two weeks, are expected to be held overnight to permit video testimony from 10 to 15 witnesses in Afghanistan, including women and children survivors of the attack.
If convicted of premeditated murder, he could face the death penalty. A minimum penalty on the charge is a life sentence with the possibility of parole.