A CNN Special Investigation drills down on the causes and the impact of the Fort Hood shootings, at 8 p.m. ET Saturday on CNN TV.
Fort Hood, Texas (CNN) -- A picture began to emerge Thursday of the suspect in the Fort Hood shootings as a mental health professional who worked to help others in high-stress situations.
The gunman was identified as Maj. Nidal Malik Hasan, 39, a law enforcement source told CNN. Hasan's office at the base's Darnall Army Medical Center is about a mile from the shootings, where 13 people were killed and 30 were wounded.
Hasan had been telling his family since 2001 that he wanted to get out of the military, said a spokeswoman for his cousin, Nader Hasan. Hasan told his family he had been taunted after the September 11 attacks, the spokeswoman said.
"He was mortified by the idea of having to deploy," his cousin told the New York Times. "He had people telling him on a daily basis the horrors they saw over there."
An owner of a 7-Eleven at Fort Hood said Hasan -- whom he knows as "Major Nidal" -- came in for coffee and hash browns most mornings, including the morning of the shootings. Surveillance video from the store obtained by CNN shows a man who according to the store owner is Hasan at the cashier's counter at about 6:20 a.m. Thursday, about seven hours before the mass shooting. He was carrying a beverage and dressed in traditional Arab garb. Another surveillance video from Tuesday showed the man in scrubs.
"He looked normal," the owner said. "Came in had his hash browns and coffee as you see in the surveillance video."
The owner said he was too busy to chat with Hasan on Thursday, but through brief talks learned the officer's background was Jordanian, though he didn't speak Arabic well. He said Hasan didn't wear a wedding ring and jokingly asked several times whether the owner knew a bride for him.
Hasan would also ask the owner whether he planned to attend Friday prayers. The owner would say he was too busy.
Hasan said he would be deployed to Afghanistan soon, the owner said.
Sen. Kay Bailey Hutchison, R-Texas, who had been briefed by a general at the post, told CNN that Hasan was to have been deployed to Iraq and was unhappy about it.
Staff Sgt. Marc Molano, based at Fort Knox, Kentucky, told CNN Hasan treated him for post-traumatic stress disorder earlier this year at Walter Reed Army Medical Center in Washington.
"Dr. Hasan provided me with nothing but the best care," Molano said. "He was a very well-mannered, polite psychiatrist, and it's just a shock to know that Dr. Hasan could have done this. It's still kind of hard to believe."
Molano described him as "far and away one of the best psychiatrists I ever dealt with."
A soldier who served two tours in Iraq and is awaiting medical retirement for chronic PTSD and severe mental disorders called Hasan "a soldier's soldier who cared about our mental health."
"Hasan hears nothing but these horror stories from soldiers who come back from Iraq and Afghanistan," the soldier said. "Just hearing it I'm pretty sure would have a profound effect."
Mindy B. Mechanic, an associate professor of psychology at California State University, Fullerton, said listening to horror stories can have an impact, but such as extreme one is unlikely.
The impact on therapists who work with traumatized individuals is known as vicarious traumatization or compassion fatigue, Mechanic said.
"But they don't go out on shooting sprees," she said. "They might get depressed or have some emotional fallout from it, but to go on a shooting spree is not part of what happens to people from having to deal with trauma survivors all the time."
Mechanic, who does not know Hasan, said people don't just snap. "When you start looking back, there are crumbs that suggest everything was not hunky-dory."
A former neighbor of Hasan said he lived in a highrise apartment complex in Silver Spring, Maryland, with another man, apparently his brother, and that the two appeared friendly.
"They had some Arabic signs out there, and I asked them what they meant," said the woman, who asked not to be identified. The other man, who routinely wore a chef's outfit, told her it was a prayer, she said. "They seemed like they were nice people," she said.
The two men moved out three or four months ago, which she noticed because the Muslim prayer had been removed from their door.
"Honestly, they seemed like very cool, calm guys, and religious guys," she said. "It's kind of strange."
According to military records, Hasan was born in Virginia, and a federal official said he was a U.S. citizen of Jordanian descent.
Military records show Hasan received his appointment to the Army as a first lieutenant in June 1997 after graduating from Virginia Tech in Blacksburg, Virginia, with a degree in biochemistry.
Six years later, he graduated from the Uniformed Services University of the Health Sciences' F. Edward Hebert School Of Medicine in Bethesda, Maryland. He was an intern, resident and a fellow at Walter Reed Army Medical Center.
He was promoted to captain in 2003 and to major in May.
This year Hasan completed a fellowship in disaster and preventive psychiatry and was assigned to Darnall in July.
He had been awarded the National Defense Service Medal, the Global War on Terrorism Service Medal and the Army Service Ribbon, but was never deployed outside the United States.
CNN's Octavia Nasr, Tracy Sabo and Kevin Bohn contributed to this story.