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, the suspect in the assault that killed 13 people and wounded 30 at Fort Hood, Texas, 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.
Grandma: He was troubled
His maternal grandmother told NBC News that he was extremely unhappy at Fort Hood. Salha Hamad, 84, said Hasan told her he was very troubled by his upcoming deployment.
Hamad said her grandson was a “good boy” and a “good doctor with a good heart” with whom she would speak frequently on the phone.
In tears as she spoke from her home in Ramallah, West Bank, she said Hasan was particularly upset by seeing soldiers who were suffering as a result of being injured in Iraq and Afghanistan.
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."
Possible tie to online posts
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."
Allegedly said: 'Muslim first'
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.
A 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.
Hasan was born and raised in Arlington, Va., the son of Palestinian parents who immigrated to the United States from Albireh, a West Bank suburb of Ramallah. His grandmother told NBC News that many members of his extended family have American citizenship and she has a U.S. green card.
In a statement Friday, Kim Fuller, a spokeswoman for Hasan's family, said relatives in Virginia were reaching out to law enforcement to offer any help they can into the investigation.
The family said his actions don't reflect how they were raised in the U.S. Still, while there have been reports that he was harassed for his Muslim religion, there is no indication Hasan filed a complaint within the military about that.
Noel Hasan said her nephew "did not make many friends" and would say "the military was his life."
A cousin, Nader Hasan, told The New York Times that after counseling soldiers returning from Iraq and Afghanistan with post-traumatic stress disorder, Hasan knew the scars of war well.
"He was mortified by the idea of having to deploy," Nader Hasan said. "He had people telling him on a daily basis the horrors they saw over there."
Retired Army Col. Terry Lee, who said he worked with Hasan, told Fox News that Hasan had hoped Obama would pull troops out of Afghanistan and Iraq. Lee said Hasan got into frequent arguments with others in the armed forces who supported the wars, and had tried hard to prevent his pending deployment.
Col. Kimberly Kesling, deputy commander of clinical services at Darnall Army Medical Center at Fort Hood, said she had known Hasan.
"You wouldn't think that someone who works in your facility and provided excellent care for his patients, which he did, could do something like this," Kesling said. She described him as "a quiet man who wouldn't seek the limelight" and said she was shocked when she heard he was the suspect in the shootings.
Imam recalls 'committed soldier'
Hasan attended prayers regularly when he lived outside Washington, often in his Army uniform, said Faizul Khan, a former imam at a mosque Hasan attended in Silver Spring, Md. He said Hasan was a lifelong Muslim.
"I got the impression that he was a committed soldier," Khan said. He spoke often with Hasan about Hasan's desire for a wife.
His grandmother also told NBC that she frequently spoke with him about getting married, but he said he was so stressed by his work, that he never had time to meet anyone.
On a form filled out by those seeking spouses through a program at the mosque, Hasan listed his birthplace as Arlington, Va., but his nationality as Palestinian, Khan said.
"We hardly ever got to discussing politics," Khan said. "Mostly we were discussing religious matters, nothing too controversial, nothing like an extremist."
During an interview on NBC’s Today Show, Lt. Gen. Robert Cone, the base commander, said soldiers reported that the gunman shouted “Allahu akbar!” — an Arabic phrase for “God is great!” — before opening fire. He said officials had not yet confirmed that Hasan made the comment.
Hasan earned his rank of major in April 2008, according to a July 2008 Army Times article.
He served eight years as an enlisted soldier. Military records show he also served in the ROTC as an undergraduate at Virginia Tech in Blacksburg and received a bachelor's degree in biochemistry there in 1997.
But college officials said Friday that Hasan graduated with honors in biochemistry in 1995 and there was no record of him serving in any ROTC program.
He previously had attended Barstow Community College in Barstow, Calif., and Virginia Western Community College in Roanoke, Va., according to Virginia Tech records.