FORT HOOD, Texas — As if going off to war, Maj. Nidal Malik Hasan cleaned out his apartment, gave leftover frozen broccoli to one neighbor and called another to thank him for his friendship — common courtesies and routines of the departing soldier. Instead, authorities say, he went on the killing spree that left 13 people at Fort Hood, Texas, dead.

Investigators examined Hasan’s computer, his home and his garbage Friday to learn what motivated the suspect, who lay in a coma, shot four times in the frantic bloodletting. Hospital officials said some of the wounded had extremely serious injuries and might not survive.

The 39-year-old Army psychiatrist emerged as a study in contradictions: a polite man who stewed with discontent, a counselor who needed to be counseled himself, a professional healer now suspected of cutting down the fellow soldiers he was sworn to help.

Relatives said he felt harassed because of his Muslim faith but did not embrace extremism. Others were not so sure. A recent classmate said Hasan once gave a jarring presentation to students in which he argued the war on terrorism was a war against Islam, and “made himself a lightning rod for things” when he felt his religious beliefs were challenged.

Investigators were trying to piece together how and why Hasan allegedly gunned down his comrades in the worst case of violence on a military base in the U.S. The rampage unfolded at a center where some 300 unarmed soldiers were lined up for vaccines and eye tests.

Soldiers reported that the gunman shouted “Allahu Akbar!” — an Arabic phrase for “God is great!” — before opening fire Thursday, said Lt. Gen. Robert Cone, the post commander. He said officials had not confirmed Hasan made the comment.

Hasan’s family said in a statement Friday that his alleged actions were deplorable and don’t reflect how the family was reared.

“Our family is filled with grief for the victims and their families involved in yesterday’s tragedy,” said Nader Hasan, a cousin who lives in northern Virginia. “We are mortified with what has unfolded and there is no justification, whatsoever, for what happened.”

The 30 people wounded were dispersed among hospitals in central Texas. W. Roy Smythe, chairman of surgery at Scott and White Memorial Hospital, said several patients were still at “significant risk” of losing their lives. Army briefers told lawmakers in Washington that eight other people were treated for at a hospital for stress and trauma, said Lindsey Mask, a spokeswoman for Rep. Buck McKeon, R-Calif.

The dead included a pregnant woman who was preparing to return home, a man who quit a furniture company job to join the military about a year ago, a newlywed who had served in Iraq and a woman who had vowed to take on Osama bin Laden after the Sept. 11 terrorist attacks.

Army Chief of Staff George Casey said he asked bases around the country to assess their security. He also said he was worried about a backlash against the thousands of Muslim soldiers serving dutifully in uniform.

Hasan was due to be deployed to Afghanistan to help soldiers with combat stress, a task he’d done stateside with returning soldiers, the Army said. Army spokeswoman Col. Cathy Abbott was uncertain when Hasan was to leave but he was in the preparation stage of deployment, which can take months.

In any event, the major was saying goodbyes and dispensing belongings to neighbors.

Jose Padilla, the owner of Hasan’s apartment complex, said Hasan gave him notice two weeks ago that he was moving out this week.

Earlier this week, Hasan asked Padilla his native language. When Padilla said it was Spanish, Hasan immediately went up to his apartment to get him a Spanish-language Quran. Padilla said Hasan also refused to reclaim his deposit and last month’s rent, surrendering $400 that the major said should go to someone who needed it.

“I cannot comprehend that the enemy was among us,” Padilla said, as he teared up. “I feel a little guilt that I was basically giving housing to someone who is going to do so much destruction.”

Neighbor Patricia Villa said Hasan came to her apartment the day of the shooting, and before, to give her vegetables, an air mattress, T-shirts, a Quran and offer her $60 to clean his Killeen, Texas, apartment after he left.

Jacqueline Harris, 44, who lives with her boyfriend, Willie Bell, in the apartment next door to Hasan, said he called Thursday at 5 a.m. and left a message.

“He just wanted to thank Willie for being a good friend and thank him for being there for him,” Harris said. “That was it. We thought it was just a nice message to leave.”

Bell said Hasan offered a farewell, saying, “Nice knowing you, old friend. I’m going to miss you.”

According to a Killeen police report in August, an Army employee was charged with scratching Hasan’s car, causing $1,000 in damage. Apartment manager John Thompson said the man charged was a soldier back from Iraq, who objected to Hasan’s faith and ripped a bumper sticker off the major’s car that said: “Allah is Love.”

Kim Rosenthal, another neighbor, said Hasan didn’t seem too upset by his scratched vehicle, even though it was damaged so badly that he got a new one. “He said it was Ramadan and that he had to forgive people,” Rosenthal said. “He forgave him and moved on.”

Hasan appeared less forgiving to Dr. Val Finnell when they were classmates in a 2007-08 master’s public health program at the Uniformed Services University of the Health Sciences in Bethesda, Md.

He said that at a class presentation by public health students, at which topics like dry cleaning chemicals and house mold were discussed, Hasan talked about U.S. military actions as a war on Islam. Hasan made clear he was a “vociferous opponent” of U.S. wars in Muslim countries, Finnell said.

“He made himself a lightning rod for things,” Finnell said. “No one picked on him because he was a Muslim.”

Law enforcement officials said they are trying to confirm if Hasan wrote Internet postings that include his name about suicide bombings and other threats, equating suicide bombers to soldiers who throw themselves on a grenade to save the life of fellow soldiers.

Hasan is the Arlington, Va.-born son of Palestinian parents who ran a restaurant and bar in Roanoke, Va., from 1987 to 1995 and owned a small grocery store in that city.

His relatives in the West Bank said they had heard from family members that Hasan felt mistreated in the Army as a Muslim.

“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. “He hired a lawyer to get him a discharge.”

Mohammed Hasan said outside his home in Ramallah that he heard about the shooting from a relative. “I was surprised, honestly, because the guy and his brothers are so calm, and he, as I know, loves his work.”

Nidal Hasan is the eldest of three brothers. One brother, Annas, lives in Ramallah with a wife and daughter, and practices law. The youngest brother, Eyad, lives in Virginia.

“We don’t mix with them a lot,” Mohammed said. “Nidal like to stay alone, he was very calm. He minded his own business.”

Hasan graduated from medical school at the Uniformed Services University in 2003, said Sharon K. Willis, speaking for the school.

He then entered a psychiatry residency program at Walter Reed Army Medical Center, which he completed in 2007. He returned to the university for the disaster and military psychiatry fellowship in 2007.

The first phase of that fellowship is earning a master of public health degree, which he completed in 2008. He completed the fellowship program in June.

A month later, Hasan reported for duty at Fort Hood.

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Blackledge reported from Washington. Associated Press writers Lara Jakes, Lolita C. Baldor, Cal Woodward, Devlin Barrett, Brett Zongker and Jessica Gresko in Washington; Sue Lindsey in Roanoke, Va.; April Castro and Jeff Carlton in Killeen, Texas; Dalia Nammari in Ramallah, West Bank; and AP’s News Research Center in New York contributed to this report.