TACOMA, Washington -- Military prosecutors said on Monday they would seek the death penalty for a U.S. soldier accused of killing 16 Afghan villagers when he twice ventured out of his camp earlier this year.

The lead prosecutor, Lieutenant Colonel Jay Morse, told a preliminary hearing he would present evidence proving "chilling premeditation" on the part of Staff Sergeant Robert Bales, a decorated veteran of four combat tours in Iraq and Afghanistan.

The shootings of mostly women and children in Afghanistan's Kandahar province in March marked the worst case of civilian slaughter blamed on an individual U.S. soldier since the Vietnam War and eroded already strained U.S.-Afghan ties after more than a decade of conflict in the country.

Bales faces 16 counts of premeditated murder and six counts of attempted murder, as well as charges of assault and wrongfully possessing and using steroids and alcohol while deployed.

Morse said he was submitting a "capital referral" in the case, requesting that Bales be executed if convicted.

The hearing at Joint Base Lewis-McChord in Washington State was expected to last two weeks and include witness testimony from Afghanistan carried by live video, including testimony from villagers and Afghan soldiers.

At the end, military commanders will decide whether there is sufficient evidence for Bales to stand trial by court-martial.

'I just shot up some people'
Bales, dressed in camouflage Army fatigues with his head shaven, embraced his wife Kari in court before the hearing began. He then sat silently watching the proceedings from the defense table as Morse summarized the prosecution's account of the events of March 10-11.

According to Morse, Bales had been drinking with two fellow soldiers before he left his base, Camp Belambay, and went to a village where he committed the first killings.

Morse said Bales then returned to the camp and told a drinking buddy, Sergeant Jason McLaughlin, "I just shot up some people," before leaving for a second village and killing more people. Morse called Bales' actions "deliberate, methodical."

According to McLaughlin, Bales asked him to smell his rifle and said "I'll be back at 5 (a.m.). You got me?" McLaughlin said he did not think Bales was serious, and "didn't think too much about it," going back to sleep for guard duty that started at 3 a.m.

Child witnesses to Afghan massacre: Bales was not alone

Prosecutors showed a video shot by night-vision camera from a surveillance balloon over the camp, showing a figure they identified as Bales walking back to the post wearing a dark blue bed sheet or throw rug tied around his neck like a cloak.

He is seen being confronted by three soldiers, including the two men prosecutors said he had been drinking with, who ordered him to drop his weapons and took him into custody as he is heard saying, "Are you ****ing kidding me?"

One of the three, Corporal David Godwin, testified that Bales kept repeating the words, "I thought I was doing the right thing," and "It's bad. It's bad. It's really bad." Several witnesses said Bales' trousers were spattered with blood. One said he had a "ghost-like look."

Drank whiskey, watched assassin film
Godwin recounted that he, Bales and McLaughlin had been drinking whiskey together in McLaughlin's room while watching the Hollywood film "Man on Fire," which stars Denzel Washington as a former assassin bent on revenge.

Several witnesses from the camp said Bales had been aggrieved over the lack of action over an improvised explosive device attack on a patrol near the camp several days earlier, in which one U.S. soldier lost the lower part of a leg.

Officials: US soldier in Afghanistan shooting spree said 'I did it'

Prosecutors said Bales had been armed with a rifle, a pistol and a grenade launcher on the night in question, and that the killings took place over a five-hour period in two villages. The dead included members of four families, most shot in the head.

When Bales returned to the camp and surrendered his weapons, he was brought to Captain Daniel Fields, team leader, at the camp's command center. "What the **** just happened?" Fields said he asked Bales. He said Bales avoided eye contact and just said "I'm sorry, I let you down."

Bales was not expected to testify during the so-called Article 32 hearing.

John Henry Browne, Bales' civilian lawyer, has suggested Bales may not have acted alone and may be suffering from post-traumatic stress disorder.

Kari Bales told NBC station KING5.com before Monday's hearing that she believed he was innocent, as a massacre of innocent civilians was "not something my husband would have done ... not the Bob that I know."

No motive has emerged for the killings.

Kari Bales had complained about financial difficulties on her blog in the year before the killings, and she had noted that Bales was disappointed at being passed over for a promotion.

Browne described those stresses as garden-variety — nothing that would prompt such a massacre — and has also said, without elaborating, that Bales suffered a traumatic incident during his second Iraq tour that triggered "tremendous depression.”

Asked about the prospect of the death penalty, Kari Bales told KING5 that she had not “had time to worry about that.”

“I know that’s a possibility,” she added. “If and when that happens then that’s the time I will worry about it. It’s in God’s hands.”

Reuters and The Associated Press contributed to this report.

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