Seattle attorney John Henry Browne told The Associated Press that according to his client's family, the suspect was standing next to another U.S. soldier when that soldier was gravely injured.
"We have been informed that at this small base that he was at, somebody was gravely injured the day before the alleged incident - gravely injured, and that affected all of the soldiers," he said.
Browne said his client had been reluctant to leave on his fourth deployment and surprised to be deployed to Afghanistan.
He offered no other details of the incident, and it isn't clear whether it prompted the horrific middle-of-the-night attack. The soldier had been injured twice during his three previous deployments to Iraq, and he was loath to go to Afghanistan to begin with, Browne said.
Browne declined to release his client's name, citing concerns for the soldier's family, which is under protection on Joint Base Lewis-McChord, near Tacoma. But he said the soldier has two young children, ages 3 and 4.
The soldier, a 38-year-old father of two who is originally from the Midwest, deployed last December with the 3rd Stryker Brigade, and on Feb. 1 was attached to a "village stability operation." Browne described him as highly decorated and said he had once been nominated for a Bronze Star, which he did not receive.
But he did say that the soldier and his family thought he was done fighting. During tours in Iraq, the soldier suffered a concussive head injury in a car accident caused by a roadside bomb, Browne said, and he suffered a battle-related injury that resulted in surgery to remove part of his foot.
He was screened by health officials after the head injury before he redeployed, Browne said. He did not know if his client had been suffering from post-traumatic stress disorder, but said it could be an issue at trial if experts believe it's relevant.
He and the rest of his brigade had initially been told they wouldn't have to go to Afghanistan, Browne said.
Browne and his co-counsel, Emma Scanlan, said they had met with the soldier's wife and other family members, and Browne said he spoke briefly by phone with the soldier, whom he described as stunned and distant.
His family was shocked: "They were totally shocked," he said. "He's never said anything antagonistic about Muslims. He's in general very mild-mannered."
Browne said he knew little of the facts of the shooting, but disputed reports that a combination of alcohol, stress and domestic issues caused him to snap. He said the family said they were unaware of any drinking problem, and described the couple's marriage as "fabulous."
The soldier is suspected of going on a shooting rampage in villages near his base in southern Afghanistan early Sunday, killing nine children and seven other civilians and then burning some of their bodies. The shooting, which followed a controversial Quran-burning incident involving U.S. soldiers, has outraged Afghan officials.
The suspect was flown out of Afghanistan on Wednesday evening to what officials describe as a pretrial confinement facility in Kuwait. Officials have anonymously described him as a father of two who has been in the military for 11 years. He has served three tours in Iraq and began his first deployment to Afghanistan in December.
The soldier asked to be represented by Browne when he was taken into custody, the lawyer said.
Browne said he's spoken with the soldier, but did not discuss the substance of the allegations. He said the soldier had no prior events in his Army dossier indicating misbehavior.
Browne once defended serial killer Ted Bundy and recently represented Colton Harris-Moore, a youthful thief known as the "Barefoot Bandit."
Browne said he has only handled three or four military cases before. The soldier will also have at least one military lawyer.
Military lawyers say once attorneys involved in the initial investigation of an alleged crime involving a service member have what they believe to be a solid understanding of what happened and are satisfied with the evidence collected, they draft charges and present them to a commander.
That person then makes a judgment on whether there is probable cause to believe that an offense was committed and that the accused committed it.
That commander then "prefers" the charges to a convening authority, who typically is the commander of the brigade to which the accused is assigned but could be of higher rank.