Fort Hood Gunman Recently Reassigned From Infantry Duties

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Spc. Ivan Antonio Lopez, the soldier who killed three service members before committing suicide at Fort Hood, Texas, was an experienced infantryman who arrived at his new post just two months ago with new duties in support and transportation, service records showed Thursday.

Lt. Gen. Mark Milley, Fort Hood's commander, confirmed Lopez's identity on Thursday after his family was officially notified. He repeated that while nothing had been ruled out, the attack Wednesday didn't appear to have been an act of terrorism.

There were "strong indications" that the tragedy sprang from an argument with another service member, Milley said.

Military service records show that Lopez, 34, was from Guayanilla, Puerto Rico.

He joined the Army in April 2010 as a private first class, bringing 11 years' experience in Puerto Rico's Army National Guard, where he served in a light infantry regiment and played in the 248th Army Band. With the National Guard, he was deployed to Egypt for the entire year of 2007.

Once in the Army, he was assigned to Fort Bliss, Texas, again in an infantry regiment with the 1st Armored Division. He was promoted to specialist within seven months and was deployed to Iraq in August 2011, returning home four months later.

Ivan Lopez with the Army National Guard in Puerto Rico.Puerto Rico National Guard

Lopez was a rifleman with the 1st Armored. But in December, he was reclassified as a motor transport operator, and in February he arrive at Fort Hood — with the 49th Transportation Movement Control Battalion, not the infantry.

Milley wouldn't talk about Lopez's military career, including why he was reassigned from the infantry.

Photos and comments of Lopez's Facebook page suggest that he was an enthusiastic infantryman; below one photo, he wrote: "50 caliber sniper rifle. The dream of any shooter of long and precise reach."

But there was no immediate public indication that he was disgruntled about his new duties. Neighbors told NBC News that he and the woman and young girl he lived with in Killeen — whom they believed to be his wife and daughter — were pleasant and seemed happy, although they generally kept to themselves.

The FBI also had no indication of anything amiss with Lopez, a federal law enforcement official told NBC News.

Ivan Lopez with the Army National Guard in Puerto Rico.Puerto Rico National Guard

Instead, Milley said, Lopez exhibited symptoms of "unstable psychiatric or psychological conditions." Army officials said Wednesday that he was under treatment for depression and anxiety pending a possible diagnosis of post-traumatic stress disorder.

"So he was in the system, and he was being looked at," Milley said.

In his almost exactly four years in the Army, Lopez received two Army Commendation Medals, four Army Achievement Medals, two National Defense Service Medals and the Iraq Campaign Medal (with campaign star), among other commendations. None of them were related to combat, which he didn't see in Iraq.