The official declined to provide additional details about Bales, who is suspected of walking off his base in southern Afghanistan on Sunday and gunning down the 16 villagers, including nine children and three women.
Earlier, the soldier’s attorney said the staff sergeant was scheduled to arrive on Friday at the Fort Leavenworth army base in Kansas, where he will be held in maximum security. Fort Leavenworth has the U.S. Defense Department’s only maximum-security facility.
The 38-year-old soldier, whose military unit is based south of Tacoma, Washington, had been held in Kuwait after he was flown out of Afghanistan on Wednesday.
Bales has not yet been charged in the incident. U.S. military officials have said they would not publicly identify the soldier until he is charged.
“I would assume he’ll be charged pretty fast,” said Jeffrey Lustick, a defense attorney and former Air Force military prosecutor and defense attorney in Bellingham, Washington.
The soldier is expected to face justice under U.S. military rules, but it is not clear where any trial would take place.
Photos of a soldier identified as Bales, wearing camouflage and battle gear, appeared in an article about training for soldiers headed for Afghanistan on a web publication linked to Fort Irwin, a California military base. According to the website, the photos were taken in August.
Seattle attorney John Henry Browne told Reuters that post-traumatic stress disorder, or PTSD, would likely be part of the defense of the four-tour veteran.
“It is commonly used in military defense,” he said, calling it a mitigating factor. Browne has said the soldier was unhappy about returning to combat after being wounded twice in Iraq.
He added on Friday that the man had witnessed a serious injury to a comrade the day before the massacre in the southern province of Kandahar on Sunday.
“One leg was blown off,” Browne said, and the sergeant was nearby. Browne or a colleague from the defense team plan to meet the sergeant next week, he said.
It is believed that the soldier walked off the Belandai base in the middle of the night last Sunday and began shooting Afghan villagers in two nearby villages, according to a congressional source.
The shooting of villagers has harmed relations between Afghanistan and the United States. Afghan President Hamid Karzai has accused the Pentagon of failing to fully cooperate with an investigation into the killings.
Browne told CNN that he had spoken with his client earlier in the morning, and in the short conversation the soldier “sounded distant and kind of like a deer in the headlights, but okay.”
At a news conference on Thursday, Browne described his client as “an exemplary soldier” who was upset at having to do a fourth tour of duty in a war zone and was likely suffering from stress after seeing colleagues wounded.
An unnamed U.S. official had told The New York Times the killings were a result of “a combination of stress, alcohol and domestic issues – he just snapped.”
But Browne said on CNN that marital problems were “totally bogus.” He said his client has a “very strong marriage and, frankly, we’re all taking offense at that.”
Karzai met with village elders and families of victims of the shootings on Friday and appeared to back their belief that a single gunman could not have killed so many people and in different places some distance apart.
On Thursday Karzai called for NATO troops to leave Afghan villages and confine themselves to major bases, underscoring fury over the massacre and clouding U.S. plans to withdraw its troops from Afghanistan by the end of 2014.