Staff Sergeant Robert Bales met with his attorney John Henry Browne for the first time, behind the walls of Fort Leavenworth.
"I can't think of a more difficult case, I mean every challenge, this case has political ramifications, legal ramifications, it has social ramifications,” said Browne.
Bales could be formally charged this week for killing 16 Afghan civilians, nine of them children.
People who know the 38-year-old father of two are shocked.
Captain Chris Alexander served with Bales for several years, and expressed surprise.
“No job too menial or too dangerous. And he would always get it done, and get it done very well,” said Alexander.
The killings have sparked outrage in Afghanistan.
President Hamad Karzai says American and NATO forces should pull out of the villages and return to their bases.
But the White House says the mission in Afghanistan has not changed.
"Stabilizing Afghanistan sufficiently so we can train up and transfer authority to afghan security forces and withdraw our troops as we do that,” said Jay Carney, White House spokesman.
Bales joined the military after the 911 attacks and did four tours in the Middle East.
He was injured twice, his lawyer says Bales lost part of his foot and suffered a concussion.
"Everybody that has had three or four deployments to the Middle East is probably going to have some form of PTSD,” said Browne.
Experts say even if charges are filed this week, the case may not go to trial for months.