FORT HOOD, Texas (AFP) - Investigators probing the massacre of 13 people at a Texas army base were Sunday trying to piece together the motive behind the shooting believed to be the act of a lone army gunman.
As US President Barack Obama prepared to attend a memorial Tuesday, 200-plus investigators worked round-the-clock to uncover how and why 39-year-old army psychiatrist Nidal Hasan allegedly went on the rampage at Fort Hood military base.
"All evidence at this point indicates the suspect allegedly acted alone," said army investigation spokesman, Chris Grey, appearing to strike down any theories that Hasan was part of a radical Islamist sleeper-cell.
As religious services were held in and around the base Sunday, the army's Criminal Investigation Command formally called for witnesses to come forward.
They also asked for clothes or other personal effects that may contain gunshot residue, or any items to help put together a ballistic portrait of Thursday's fateful events at building 42003, a troop processing center. Hasan's family grapple motives
From their work, and the testimony of those who met Hasan, a picture has emerged of a deeply religious American of Palestinian descent, who opposed his country's prosecution of wars in Afghanistan and Iraq.
Hasan was to be deployed to Afghanistan later this month, army officials said.
Garrison chaplain Colonel Frank Jackson described having an amiable chat with Hasan a few months ago, when the pair discussed the purchase of Muslim prayer rugs.
"He just happened to be in our office area, and like I do when I see somebody who doesn't work for me I said 'hi'," Jackson told AFP.
"I asked him if there was anything I could do to assist the Muslim congregation.
"He said it was a great service, everything was doing great. I told him we needed to buy prayer rugs and I asked him where to go and he gave me a name of some place."
An initial search of Hasan's computer revealed no direct exchanges with known extremists, but US Army and FBI officials had yet to rule out completely possible links to terrorist groups, US media reported.
Earlier this year, the Federal Bureau of Investigation learned of Internet postings by a man calling himself Nidal Hasan that expressed support for suicide bombings.
Witnesses reportedly heard Hasan, who investigators believe fired more than 100 rounds during the incident, shout "Allahu Akbar!" (God is greatest) before opening fire. Thirty people were also injured in the carnage.
But US commanders, fearing a backlash against Muslim troops -- prized for their cultural and linguistic knowledge, warned against jumping to any conclusions about the shooter's motivation.
Army chief of staff George Casey warned deadly shootings at Fort Hood could prompt a backlash against the estimated 3,500 Muslims serving in the US military. Related article: US general warns of Muslim 'backlash'
"I worry that the speculation could cause something that we don't want to see happen."
Sixteen of the 30 people wounded by volleys from the semi-automatic and the handgun allegedly wielded by Hasan, remained in hospital on Sunday as doctors warned many would be permanently scarred by their injuries.
The suspect himself, who was shot by a female civilian police officer who was being hailed as a heroine, was taken off a ventilator, but was still in intensive care.
Meanwhile details were released of each of those killed.
The victims included a 21-year-old mother-to-be Private Francheska Velez, who was due to return home to Chicago for maternity leave after a tour in Iraq, and 56-year-old John Gaffaney, a psychiatric nurse who had just persuaded the military to let him return to active duty for deployment in Iraq.
Private First Class Kham Xiong, 23, was a father of three whose own father had fought communist forces in Laos during the Vietnam war.
Specialist Ryan Hill, 28, came to the base with his young daughter Emma to put flowers and candles at the main gates as a mark of respect to the victims.
"It makes me mad. I don't how somebody can commit an act like that," Hill told AFP. "Those soldiers were ready to take off and deploy and they won't even get to do that."
Others rallied by taking food to the headquarters of the 20th Engineer Batallon -- which lost four men in the shooting -- to be distributed for the victims' families.
"We received an e-mail saying we could bring food. I brought spaghetti. We didn't know any of the victims but we are still shaken", said Misty Wright, whose husband is in the Army.
