(Recasts with testimony from Bales)
By Jonathan Kaminsky
TACOMA, Washington, Aug 22 (Reuters) - A decorated U.S. soldier who gunned down 16 unarmed Afghan civilians in a nighttime rampage apologized on Thursday at a sentencing hearing to determine his fate, calling the killings "an act of cowardice."
Army Staff Sergeant Robert Bales, a veteran of four combat tours in Iraq and Afghanistan, has admitted to shooting the villagers, mostly women and children, in attacks on their compounds in Kandahar province in March 2012.
"Sorry just isn't good enough, but I am sorry," Bales told a jury in a military courtroom in Washington state. "What I did is an act of cowardice."
Bales pleaded guilty to the killings in June in a deal that will spare him the death penalty. The jury of six military personnel is tasked with deciding if he will spend the rest of his life in prison or if he will be eligible for parole after 20 years.
Defense lawyers have been seeking to show that Bales suffered a breakdown under the pressure of his final deployment to Afghanistan, and say he suffered from post traumatic stress disorder and a brain injury even before his last deployment to Afghanistan.
"I don't think anybody with a rational mind could say Bob Bales didn't snap," Browne told reporters on Wednesday after the court-martial session before a military jury.
Army prosecutors have said Bales acted alone and with chilling premeditation when, armed with a pistol, a rifle and a grenade launcher, he left his base twice during the night, returning in the middle of his rampage to tell a fellow soldier, "I just shot up some people."
The prosecution rested its case on Wednesday after calling to the stand a string of witnesses including nine Afghans, among them a man who lost six of his seven children in the attacks and a teenager who was shot in the legs but survived.
The killings marked the worst case of civilian deaths blamed on a rogue U.S. soldier since the Vietnam War and further eroded strained U.S.-Afghan relations after more than a decade of conflict in that country.
Prosecutors had said they hoped to show Bales had engaged in a pattern of bad behavior that predated his multiple deployments to Iraq and Afghanistan.
Bales, who has claimed his memories of the killings are spotty, acknowledged the killings upon pleading guilty in June and told the court at the time there was "not a good reason in this world" for his actions.
During a nine-day pre-trial hearing last fall, witnesses testified that Bales had been upset by a bomb blast near his outpost that severed a fellow soldier's leg days before the shootings. (Editing by Cynthia Johnston and Andrew Hay)