None of the Afghan witnesses were able to identify Bales as the shooter, but other evidence, including tests of the blood on his clothes, implicated him, according to testimony from a DNA expert.
After the hearing concluded, Scanlan spoke with reporters, saying that in addition to questions about Bales' state of mind, there are still questions of whether there were more people involved.
During testimony, a special agent testified that months after the killings, she was able to interview a victim's wife who recounted having seen two U.S. soldiers. Later, however, the woman's brother-in-law, Mullah Baraan, who was not present at the shootings, testified the woman says there was only one shooter. The woman herself did not testify.
"We need to know if more than one person was outside that wire," Scanlan said.
Scanlan also raised the issue of post-traumatic stress disorder and brain injury, noting that Bales had received a screening at the traumatic brain injury clinic at Madigan Army Medical Center during a period of time that the center is under investigation for reversing hundreds of PTSD diagnoses of soldiers since 2007.
"We're in the process of investigating that," she said.
When asked if Bales had ever been diagnosed with PTSD, Scanlan said, "I'm not going to answer that right now."
Dan Conway, a military defense lawyer based in New Hampshire, said Tuesday that PTSD must be considered in the case.
"I think the defense team has an obligation to meet with doctors and determine if PTSD affected Bales' ability to premeditate the murders," Conway said.
Eric Zillmer, a military psychology expert at Drexel University in Philadelphia, said many people suffer from PTSD and still function just fine in society.
He noted Bales was considered fit for duty when the killings occurred, but he said PTSD could be a contributing factor to Bales' actions, which sets up a key issue to be decided.
"Is this a bad apple who should be punished?" Zillmer asked. "Or is he to some extent an actor who didn't have complete control over all his behaviors? I think it would be difficult to make PTSD completely responsible for the series of murders this perpetrator committed."
Associated Press writer Nicholas K. Geranios contributed to this report from Spokane, Wash. Follow Rachel La Corte at http://www.twitter.com/RachelAPOly or http://www.facebook.com/news.rachel