PADUCAH, Kentucky (CNN) -- Defense lawyers trying to save their client from the death penalty argued Tuesday that former U.S. soldier Steven Green exhibited clear symptoms of acute stress disorder in Iraq and that a military psychiatric nurse-practitioner failed to diagnose the troubled infantryman and pull him out of combat.
Former U.S. soldier Steven Green has been convicted of raping and killing a 14-year-old Iraqi girl.
Green was convicted last week in U.S. District Court in Kentucky of murder, rape, conspiracy and obstruction of justice.
A jury found Green guilty of a raping a 14-year-old girl, then killing her and setting her body on fire to destroy evidence. Green also was found guilty of killing the girl's parents and 6-year-old sister.
Green might become the first former U.S. soldier to face the death penalty for war crimes before a civilian court, where he was tried because he had been discharged from the military before his crimes came to light.
Four other former soldiers are in prison for their roles in the crimes and the cover-up that followed.
His lawyers offered testimony Tuesday from a psychiatrist who testified that a mental health review "did not meet acceptable mental health standards."
Dr. Pablo Stewart testified that a military nurse-practitioner who examined Green some three months before the crimes "had the answers in front of her that clearly marks all the symptoms of acute stress disorder or post-traumatic stress disorder."
Yet rather than pull Green out of combat or follow up with additional care, Stewart testified, the nurse-practitioner prescribed sleeping pills and sent Green back to his traffic checkpoint in an area known as the "Triangle of Death," one of the bloodiest areas of the Sunni-led insurgency.
Earlier, defense lawyers had identified the nurse practitioner as Lt. Col. Karen Marrs, and she was called by the defense to testify. She described Green's company as having the worst morale she'd ever seen, and she said the entire battalion was "red," meaning it was "mission incapable" -- the troops were "hostile, vengeful and needed increased control and command," without which there was a greater likelihood of misconduct.
The psychiatric nurse said it was important for soldiers to return to duty, not only to keep up troop numbers, but also because "soldiers evacuated prematurely have a hard time fitting in."
Marrs said procedures were followed, but it was difficult to keep precise records partly because soldier interviews took place under difficult conditions, in one case in a concrete structure that had a hole in the ceiling from a mortar shell.
She said troops often were counseled that "having sad and angry feelings are common," and that "you aren't a monster for having these thoughts in monstrous conditions."
At the time of Green's arrest, he told FBI agents, "You probably think I'm a monster."
Throughout the testimony Tuesday, Green repeatedly glanced at the jury. He appeared pale, wearing a light-blue button-down shirt and pressed khakis. He smiled at times while talking to his lawyers.
He seemed moved by the testimony of his uncle, Greg Simolke, who broke down several times while speaking about his nephew.
"(Steve) was one of these kids, everyone knows them, no matter what they do, nothing works out, like he had a black cloud hanging over him," Simolke said. Green lived with his uncle, an obstetrician, in North Carolina for a few months during his senior year in high school, according to testimony.
He moved back to Midland, Texas, where he was originally from, after a school counselor told him he was so far behind that he would have to take sophomore-level courses.
"I don't know if any of us realized how far behind he was," said Simolke, who went on to describe how proud he was when his nephew finished his military training.
"To me, that was a huge accomplishment for Steve," Simolke said before breaking down in tears.
Testimony in the penalty phase of the case began Monday.