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 that also wounded 30. 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 base 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. We are all asking why this happened, and the answer is that we simply do not know."

The 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.