Dr. Val Finnell was a classmate of Hasan's at the Uniformed Services University of the Health Sciences in Bethesda, Md. Both attended a master's in public health program in 2007 and 2008.
Finnell says he got to know Hasan in an environmental health class. At the end of the class, students gave presentations. Finnell says other classmates wrote on subjects such as dry cleaning chemicals and mold in homes, but Hasan's topic was whether the war against terror was "a war against Islam." Finnell described Hasan as a "vociferous opponent" of the terror war.
Finnell says Hasan told classmates he was "a Muslim first and an American second."
Thursday's shooting left 13 dead and 34 wounded. Hasan survived a gunshot wound and was in stable condition, under guard, in a local hospital as investigators try to piece together what motivated the rampage.
Investigators have located a shooting range near Fort Hood where Hasan practiced in his spare time as well as the gun store where a few weeks ago he bought the murder weapon, a semi automatic pistol which carries a clip of 20 rounds and is known on the street as a "cop killer," CBS News national security correspondent David Martin reports.
A cousin of Hasan's in the West Bank said the military psychiatrist had little contact with his Palestinian relatives but had told family there that he suffered discrimination in the U.S. Army because he is a Muslim.
Mohammed Malik Hasan told the AP he had not heard from his cousin since a visit to the West Bank 15 years ago but that he heard from other relatives in the U.S. that he was distressed on learning he was to be deployed to Afghanistan. Hasan said his cousin had hired a lawyer to seek a military discharge.
Speaking in Ramallah Friday, he described Maj. Nidal Malik Hasan as "religious and not very social but ... very normal."
More Coverage of the Tragedy at Fort Hood:
Hasan Likely "Lone Wolf," Officials Say
Hasan Reportedly Felt U.S. Attacked Islam
List of Fort Hood Dead, Wounded
Neighbor: Ft. Hood Suspect Packed Up Home
"Allahu Akbar": Hasan's Words as He Fired?
Mosques Up Security in Wake of Ft. Hood
Obama: Don't Jump to Conclusions
Hasan's Actions "Despicable," Family Says
Female Cop Hailed as Ft. Hood Hero
Store's Video May Show Ft. Hood Suspect
U.S. Army Base Violence Has Bloody History
Tragedy at Fort Hood
Accounts of Hasan's life paint a complex and, at times, contradictory picture. 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.
His job as a military psychiatrist was to salve 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.
While it's early in the investigation, investigators are looking at the case as a "lone wolf" situation, senior law enforcement officials told CBS News correspondent Bob Orr.
The FBI is going through his computer records - looking for web sites visited, contacts and writings. Investigators are also going through cell phone records, reports Orr.
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.
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."
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 President Barack 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.
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.
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."
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.