He was by turns caring and contentious, a man quick to say "I am blessed" in casual greeting yet one who seemed to stew in discontent that he could not always keep to himself.

Army psychiatrist Nidal Malik Hasan, suspect in the assault that killed 13 people at Fort Hood, Texas, and hurt 30, salved the emotional wounds of troops returning from war even as he objected to his own looming deployment to Afghanistan, where he was to counsel soldiers suffering from stress.

But Hasan argued with fellow soldiers who supported U.S. war policy, say those who know him professionally and personally. He was a counselor who once required counseling for himself because of trouble he had dealing with some patients, said a former boss.

Authorities on Friday seized Hasan's home computer, searched his apartment and took away a Dumpster as the 39-year-old Army major lay in a coma in the hospital, attached to a ventilator.

There are many unknowns about the man authorities say is responsible for the worst mass killing on a U.S. military base.

Most of all, his motive.

For six years before reporting for duty at Fort Hood, in July, Hasan worked at the Walter Reed Army Medical Center pursuing his career in psychiatry, as an intern, a resident and, last year, a fellow in disaster and preventive psychiatry. He received his medical degree from the military's Uniformed Services University of the Health Sciences in Bethesda, Md., in 2001.

While an intern at Walter Reed, Hasan had some "difficulties" that required counseling and extra supervision, said Dr. Thomas Grieger, who was the training director at the time.

Grieger said privacy laws prevented him from going into details but noted that the problems had to do with Hasan's interactions with patients. He recalled Hasan as a "mostly very quiet" person who never spoke ill of the military or his country.

"He swore an oath of loyalty to the military," Grieger said. "I didn't hear anything contrary to those oaths."

But, more recently, federal agents grew suspicious.

At least six months ago, Hasan came to the attention of law enforcement officials because of Internet postings about suicide bombings and other threats, including posts that equated suicide bombers to soldiers who throw themselves on a grenade to save the lives of their comrades.

They had not confirmed Hasan is the author of the posting, and a formal investigation had not been opened before the shooting, said law enforcement officials who spoke on condition of anonymity because they are not authorized to discuss the case.

Federal authorities seized Hasan's computer Friday during a search of his apartment in Killeen, Texas, said a U.S. military official who spoke on condition of anonymity because of the ongoing investigation.

His anger was noted by a classmate, who said Hasan "viewed the war against terror" as a "war against Islam."

Dr. Val Finnell, a classmate of Hasan's at the Uniformed Services University of the Health Sciences in Bethesda, attended a master's in public health program in 2007-2008. Finnell says he got to know Hasan because the group of public health students took an environmental health class together. At the end of the class, everyone had to give a presentation. Classmates wrote on topics such as dry cleaning chemicals and mold in homes, but Finnell said Hasan chose the war against terror. Finnell described Hasan as a "vociferous opponent" of the terror war. Finnell said Hasan told classmates he was "a Muslim first and an American second."

Hasan recently was involved in a spat with another Fort Hood soldier residing in his apartment complex, apparently related to his Muslim beliefs.

The manager of the complex, John Thompson, said the other soldier, John Van de Walker, allegedly keyed Hasan's car and also removed and tore up a bumper sticker that read "Allah is Love." Thompson said Van de Walker had been in Iraq and was upset to learn that Hasan was Muslim.

A report filed with Killeen police on Aug. 16 indicates that Hasan's vehicle, a 2006 Honda Civic, had been scratched by an unknown object causing an estimated $1,000 worth of damage. The report indicates that Van de Walker, 30, was arrested on Oct. 21 and charged with criminal mischief. The matter has been referred for prosecution, according to the report.

The phone number for Van de Walker wasn't in service Friday, and Thompson, the apartment manager, said he had moved out of the complex.

In an interview with The Washington Post, Hasan's aunt, Noel Hasan of Falls Church, Va., said he had been harassed about being a Muslim in the years after the Sept. 11, 2001, terrorist attacks and he wanted to get out of the Army. She said he had sought a discharge for several years, and even offered to repay the cost of his medical training.

Hasan was in the preparation stage of deployment, which can take months, though Army spokeswoman Col. Cathy Abbott was uncertain when Hasan was to leave. Abbott said Hasan was to deploy with an Army Reserve unit that provides what the military calls "behavioral health" counseling.

Another military official said Hasan had indicated he didn't want to go to Iraq but was willing to serve in Afghanistan. The official did not have authorization to discuss the matter publicly and spoke on condition of anonymity.

A different military official said Hasan's family has Palestinian roots. There have been reports that he was harassed for his Muslim religion, but the official says there is no indication Hasan filed a complaint with military officials about that.

Alice Thompson, the manager at the apartment complex where Hasan lived, said he'd been living there since mid-August. Thompson said she didn't talk to him other than to say hello in passing. Thompson said he always answered her "How are you?" with "I am blessed." Continued...