WASHINGTON — After two days of investigation into the mass shooting at Fort Hood, Texas, investigators have tentatively concluded that the attack was not part of a terrorist plot.

Rather, they have come to believe that Maj. Nidal Malik Hasan, the Army psychiatrist accused in the shootings, acted out under a welter of emotional, ideological and religious pressures, according to interviews with federal officials who have been briefed on the inquiry.

Investigators have not ruled out the possibility that Hasan believed he was carrying out an extremist's suicide mission.

But the investigators, working with behavioral experts, suggested that he may have long suffered from emotional problems exacerbated by the tension of his work with veterans of the wars in Iraq and Afghanistan who returned home with serious psychiatric problems.

They said his counseling activities with the veterans appear to have further fueled his anger and hardened his increasingly militant views at the same time that he seemed to move toward more extreme religious beliefs — all of which boiled over as he faced being shipped overseas, an assignment he bitterly opposed.

Investigators have gleaned most of their findings from Hasan's computer use and from interviews with his family members, co-workers and neighbors. One significant investigative thrust has involved determining whether Hasan had contact with extremists who preyed on his increasingly angry and outspoken opposition to U.S. policies in Afghanistan and Iraq.

But so far, investigators have unearthed no evidence that he was directed or steered into violence or ever traveled overseas to meet with extremist groups, as defendants in other recent terrorism cases are accused of doing, the officials said.

INVESTIGATION FLUID

The officials emphasized that their findings were preliminary and that the investigation was fluid. New information could alter their perceptions of Hasan's motives. But the early conclusions are already influencing the course of the inquiry, including which law enforcement agencies lead it.

"It's early, but it looks like there are a number of factors going on here," said a senior government official who, like others, spoke on condition of anonymity because the findings do not represent the government's formal investigative and legal views of the case.

The officials said a continuing search of Hasan's computer indicate he had logged on to websites that celebrated radical Islamic ideologies and had exchanged e-mail messages with like-minded people, some possibly overseas. In addition, they believe that he may have authored inflammatory Internet postings that justified suicide attacks, though that has not been concretely established. Still, investigators have found no evidence that Hasan e-mailed known terrorists or anyone else who encouraged or helped him to orchestrate the shootings.

U.S. Rep. Jane Harman, D-Calif., who heads the House Homeland Security intelligence subcommittee, confirmed in a phone interview Saturday that so far, investigators had not found any evidence suggesting that Hasan had been in contact with extremist or terrorist organizations. "I don't know of that link," Harman said, adding that the investigation was seeking to answer that question. The committee oversees some of the agencies involved in domestic counterterrorism inquiries.

NO KNOWN CO-CONSPIRATORS

The officials said it was increasingly unlikely that co-conspirators might still be found and charged. Based on this preliminary view, the officials said they were leaning toward charging Hasan in a military court rather than a civilian criminal court. Though the decision was not official, they said he would more likely be prosecuted in a civilian criminal court if other, nonmilitary defendants were likely to be charged.

Confirming the law enforcement view, a senior U.S. intelligence official said Saturday that there were no known co-conspirators at this point. "Hasan is the only name that's emerged so far," said the official, who insisted on anonymity when discussing intelligence matters.

The possibility that the Fort Hood attack involved terrorism arose for a number of reasons. For one, early reports from the chaotic scene indicated that there might be more than one gunman. Investigators have now said publicly that the major was the only shooter. In addition, friends and work associates of Hasan have described his increasing doubts about the U.S. military missions in Iraq and Afghanistan.

In interviews in recent days, friends and others have portrayed him as a troubled man, deeply concerned about being deployed to the war zones.

Investigators from the FBI and the Army's Criminal Investigation Command are moving deliberately through their search of Hasan's computers. They suspect he may have used multiple e-mail accounts and fictitious identities, and may have destroyed documents in advance of the attack, perhaps in an effort to conceal his activities in the days leading up to the shootings.

Such steps could be revealing and potentially legally significant as evidence that the killings were premeditated and not the spontaneous outburst of a mentally impaired malcontent.

Neighbors in the run-down two-story apartment building were Hasan has lived since arriving in Killeen, Texas, said federal agents had seized a computer belonging to his next-door neighbor. Hasan had used the computer frequently, they said, paying the neighbor for its use.

Federal agents also took away a trash bin into which the psychiatrist had dumped a shredder and a plastic bag full of shredded documents on the morning before the shooting, neighbors said.

Overall, the inquiry is somewhat more subtle than many criminal cases in which investigators try to piece together a timeline of a suspect's activities. The inquiry into the Fort Hood shootings is turning into a psychological exploration of the mind of a suspect in a mass killing.

OPENLY ANTI-WAR

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 get out of his late November deployment to Afghanistan and had struggled professionally in his work as an Army psychiatrist.

"He told (them) that as a Muslim committed to his prayers, he was discriminated against and not treated as is fitting for an officer and American," said Mohammed Malik Hasan, 24, a cousin, told The Associated Press from his home on the outskirts of the Palestinian city of Ramallah. "He hired a lawyer to get him a discharge."

After arriving at Fort Hood, Hasan was conflicted about what to tell fellow Muslim soldiers about the fighting in Iraq and Afghanistan, alarming an Islamic community leader from whom he sought counsel.

"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 in a 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 written complaint.

PERSISTENT QUESTIONS

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 against one another 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.

Danquah said he was so disturbed by Hasan's persistent questioning that he recommended the mosque reject Hasan's request to become a lay Muslim leader at Fort Hood. But he never saw a need to tell 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.

The Associated Press contributed to this report.