FORT HOOD, Texas (AP) - In retrospect, the signs of Maj. Nidal Malik Hasan's growing anger over the U.S. wars in Iraq and Afghanistan seem unmistakable. But even people who worried his increasingly strident views were clouding his ability to serve the U.S. military could not predict the murderous rampage of which he now stands accused.

In the months leading to Thursday's shooting spree that left 13 people dead and 29 others wounded, Hasan raised eyebrows with comments that the war on terror was "a war on Islam" and wrestled with what to tell fellow Muslim solders who had their doubts about fighting in Islamic countries.

"The system is not doing what it's supposed to do," said Dr. Val Finnell, who complained to administrators at a military university about what he considered Hasan's "anti-American" rants. "He at least should have been confronted about these beliefs, told to cease and desist, and to shape up or ship out."

Finnell studied with Hasan from 2007-2008 in the master's program in public health at the military's Uniformed Services University of the Health Sciences in Bethesda, Md., where Hasan persistently complained about perceived anti-Muslim sentiment in the military and injected his politics into courses where they had no place.

"In retrospect, I'm not surprised he did it," Finnell said of the shootings. "I had real questions about what his priorities were, what his beliefs were."

Hasan, who was shot by civilian police and taken into custody, was in intensive care but breathing on his own late Saturday at an Army hospital in San Antonio. Officials refused to say if he was talking to investigators.

At least 17 victims remained hospitalized with gunshot wounds, and nine were in intensive care late Saturday. On Sunday, numerous church services honoring the victims were planned both on the post and in neighboring Killeen.

Military criminal investigators continue to refer to Hasan as the only suspect in the shootings but won't say when charges would be filed. "We have not established a motive for the shootings at this time," said Army Criminal Investigative Command spokesman Chris Grey.

A government official speaking on condition of anonymity because the person was not authorized to discuss the case said an initial review of Hasan's computer use has found no evidence of links to terror groups, or anyone who might have helped plan or push him toward the shooting attack. The review of Hasan's computer is continuing, the official said.

Army investigators on Sunday were searching for additional evidence to put together a comprehensive bullet trajectory analysis. Investigators were "seeking any military or civilian personnel who may have left the scene ... with gunshot damage such as damaged privately owned vehicles," Fort Hood spokesman Chris Haug said in a statement.

Hasan likely would face military justice rather than federal criminal charges if investigators determine the violence was the work of just one person.

Sen. Joe Lieberman, chairman of the Senate Homeland Security and Governmental Affairs Committee, said he plans to begin a congressional investigation to determine whether the shootings constitute a terrorist attack.

Lieberman, an independent from Connecticut, said on "Fox News Sunday" that he wants to find out whether the Army missed warning signs that Hasan was becoming extreme in his Islamist views.

"If Hasan was showing signs, saying to people that he had become an Islamist extremist, the U.S. Army has to have zero tolerance," he said. "He should have been gone."

Army Chief of Staff George Casey warned against reaching conclusions about the suspected shooter's motives until investigators have fully explored the attack.

He said on ABC's "This Week" that focusing on Hasan's Islamic roots could "heighten the backlash" against all Muslims in the military.

Hasan's family described a man incapable of the attack, calling him a devoted doctor and devout Muslim who showed no signs that he might lash out.

"I've known my brother Nidal to be a peaceful, loving and compassionate person who has shown great interest in the medical field and in helping others," his brother, Eyad Hasan, of Sterling, Va., said in a statement. "He has never committed an act of violence and was always known to be a good, law-abiding citizen."

Still, in the days since authorities believe Hasan fired more than 100 rounds in a soldier processing center at Fort Hood in the worst mass shooting on a military facility in the U.S., a picture has emerged of a man who was forcefully opposed to the wars in Iraq and Afghanistan, was trying to elude his pending deployment to Afghanistan and had struggled professionally in his work as an Army psychiatrist.

"I told him, `There's something wrong with you,'" Osman Danquah, co-founder of the Islamic Community of Greater Killeen, told The Associated Press on Saturday. "I didn't get the feeling he was talking for himself, but something just didn't seem right."

Danquah assumed the military's chain of command knew about Hasan's doubts, which had been known for more than a year to classmates at the Maryland graduate military medical program. His fellow students complained to the faculty about Hasan's "anti-American propaganda," but said a fear of appearing discriminatory against a Muslim student kept officers from filing a formal complaint.

Others recalled a pleasant neighbor who forgave a fellow soldier charged with tearing up his "Allah is Love" bumper sticker. A superior officer at Darnall Army Medical Center at Fort Hood, Col. Kimberly Kesling, has said Hasan was quiet with a strong work ethic who provided excellent care for his patients.

Twice this summer, Danquah said, Hasan asked him what to tell soldiers who expressed misgivings about fighting fellow Muslims. The retired Army first sergeant and Gulf War veteran said he reminded Hasan that these soldiers had volunteered to fight, and that Muslims were fighting each other in Afghanistan, Pakistan and the Palestinian territories.

"But what if a person gets in and feels that it's just not right?" Danquah recalled Hasan asking him.

"I'd give him my response. It didn't seem settled, you know. It didn't seem to satisfy," he said. "It would be like a person playing the devil's advocate. ... I said, `Look. I'm not impressed by you.'"

Danquah said he was disturbed by Hasan's persistent questioning but never told anyone at the sprawling Army post about the talks, because Hasan never expressed anger toward the Army or indicated any plans for violence.

"If I had an inkling that he had this type of inclination or intentions, definitely I would have brought it to their attention," he said.

Hasan was promoted from captain to major in 2008, the same year he graduated from the master's program. Bernard Rostker, a military personnel expert at the Rand Corp., said a shortage of officers and psychiatrists meant Hasan's advancement was all but certain absent a serious blemish on his record, such as a DUI or a drug charge.

Hasan reportedly jumped up on a desk and shouted "Allahu akbar!" - Arabic for "God is great!" - at the start of Thursday's attack.

"Hopefully, they can put together the pieces and find out what in the world was in his mind and why he went crazy," Danquah said. "Aaaaah, it's sad. Those soldiers could have been my soldiers."

Associated Press Writers Allen Breed in Killeen, Texas, Dalia Nammari in Ramallah, West Bank, and Devlin Barrett, Richard Lardner, Pamela Hess and Jessica Gresko in Washington contributed to this report.