Fort Hood : It happened again, WHY DID HE DO IT?

Fort Hood shooter Ivan Lopez had mental health problems

Killeen, Texas (CNN) -- Fort Hood.

The name has been seared in the nation's collective memory since a soldier went on a deadly shooting spree here in 2009.

On Wednesday, it happened again.

 Fort Hood shooting spree: 'Texans' hearts are once again very heavy'

Specialist Ivan Lopez went from one building at the sprawling Texas military base to a second, firing a .45-caliber handgun, killing three people and wounding 16 more.

The 34-year-old Iraq vet then put the gun to his head and pulled the trigger, ending his life.

Authorities say they have not ruled out terrorism, but they were downplaying the possibility.

"There are initial reports there may have been an argument in one of the unit areas," Lt. Gen Mark Milley, the post's commanding general, told reporters late Wednesday.

Officers picked up Lopez's wife at their apartment near the base in Killeen, and she was cooperating with law enforcement, an FBI official told CNN.

The man, whom a neighbor said often gave her a friendly wave, was apparently plagued by multiple mental health issues.

Emotional torment

He had arrived at the base in February, moving with his wife and their daughter into an apartment a little more than a week before the shooting.

They appeared to be a normal couple, said neighbor Xanderia Morris. "They would smile whenever they'd see someone," she said.

But behind Lopez's smile lay a history of depression, anxiety and other psychiatric disorders, according to Milley, and he was receiving treatment and medication.

He had served for four months in Iraq in 2011. And while Army records don't show him as having been wounded there, Lopez himself reported that he had suffered a traumatic brain injury, Milley said.

He was undergoing diagnosis procedures for post-traumatic stress disorder.

"He was not diagnosed, as of today, with PTSD," Milley said.

Arriving at the diagnosis common among war veterans can take time.

Lopez was not in the process of being transitioned out of the military, Milley said.

At one time, he was part of the National Guard in Puerto Rico, but he left the Guard to join the Army, National Guard spokeswoman Ruth Diaz said Thursday.

Diaz said Lopez was active in the National Guard from 1999 to 2010. He was first assigned to the infantry battalion and later deployed, in 2007, to the Sinai Peninsula for 13 months. He joined the active duty Army in 2010.

Puerto Rico National Guard Command Sgt. Maj. Nelson Bigas, who served with Lopez for 17 months during training at Fort Hood and later in the Sinai, described Lopez as "one of the best soldiers we had in our infantry."

He told CNN that Lopez displayed no signs of mental issues or PTSD after completing his mission and returning to the island. "During, before, and after the mission, he never showed any signs of distress," said Bigas, adding that Lopez worked hard and demonstrated leadership within his team.

Bigas said the Fort Hood shooting was a "big surprise to me."

Family history:

He was married and had a daughter, around 3 years old. Just over a week ago, the family moved into an apartment complex close to the base.

Neighbor Xanderia Morris described the Lopez family as a "typical, average family."

After the news of the shooting broke on television, the wife came out crying. "She said, 'I'm just worried, I'm just worried,' " Morris said. "I tried to console her and comfort her, let her know everything was OK."

When television reports identified the shooter as Lopez, the wife became "hysterical," the neighbor said.

She was taken from the apartment by law enforcement officials, and was cooperating, an FBI source told CNN.

Gun used:

Lopez used a .45-caliber Smith & Wesson semiautomatic pistol that he had recently purchased, Milley said. He didn't know how much ammunition Lopez was carrying.

"If you have weapons and you're on base, it's supposed to be registered on base," Milley said. "This weapon was not registered on base."

Lopez passed a background check when he bought a .45-caliber Smith & Wesson handgun at Guns Galore near Killeen, Texas, according to U.S. law enforcement officials. He was found to have no criminal history that would disqualify him from the purchase, and the gun store did what was required, according to law enforcement officials who reviewed the records.

It appears that military doctors treating Lopez had not declared him mentally unfit in ways that would require reporting him to the FBI-run National Instant Criminal Background Check System, known as NICS.

The federal background check system relies on state and federal authorities to provide data on people who are mentally ineligible to buy firearms. Texas law sets a high bar to deny firearms purchases, including having been diagnosed by a licensed physician as suffering from a psychiatric disorder that is likely to cause substantial impairment in judgment and intellectual ability.

Motive:

That's the big unknown.

"There's no indication that this incident is related to terrorism, although we are not ruling anything out and the investigation continues," Milley said.

Could it have been an argument? "There are initial reports there may have been an argument in one of the unit areas, but no indication of an argument at the WTU," Milley said. WTU is the acronym for the Warrior Transition Command, where wounded, ill and injured soldiers are taught resilience skills.

He also couldn't say whether Lopez knew his victims.

Via:CNN