Wade Michael Page, the man identified as the gunman in Sunday's shooting at a Sikh temple in Oak Creek, Wis., was eyed by federal investigators "more than once" because of ties to white supremacist and extremist groups, the Los Angeles Times reports, but federal officials "determined there was not enough evidence of a crime to open an investigation."

A senior U.S. law enforcement official would not tell the paper which law enforcement agency had "looked at" Page or when that happened.

The report comes a day after the Southern Poverty Law Center said it had known about Page—a member of at least two white supremacist bands—for more than a decade. The Montgomery, Ala.-based law center said it had been tracking Page since 2000, when he "attempted to purchase goods from the neo-Nazi National Alliance, then America's most important hate group."

Seven people, including Page, were killed in Sunday's shooting at the temple. The six victims identified by police—five men and one woman—ranged in age from 39 to 84.

[Also read: Was the Sikh temple shooting domestic terrorism?]

Christopher Robillard, who served with Page for three years in the U.S. Army, said he thought it was just talk when Page expressed his extremist views.

"He would often mention the racial holy war that was coming," Robillard told CNN's Piers Morgan on Monday. "And you know, we just looked at it as he was trying to get attention to himself. Because he was always the loner type of person. Even in a group of people, he would be off alone."

More from the transcript:

I really didn't become concerned until his 2000 motorcycle trip. He told me that he was going across country to visit old friends that, you know, he had lost touch with, and I happened to be one of those. I was living in Arkansas at the time. And he stopped to visit me for about a week. And I've noticed then that he had gone through a dramatic change. And his talk about the racist war was even, you know, it was more like he really did believe it. And after he left, that was the last time I talked to him. I can't say that I wouldn't have seen this coming because honestly a couple of weeks ago, I was thinking of him. And, you know, just to see how he's been doing over the years and when I couldn't find any contact information, I did start looking for news articles, you know, that something like this might have happened somewhere, and I had missed, you know, didn't hear about it.

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Robillard said Page was discharged from the military in 1998 after showing up drunk.

A U.S. Army spokeswoman told Yahoo News that Page served from April 1992 until October 1998 as a member of the psychological operations unit. He was never deployed, but was awarded numerous medals, including two for good conduct and one for humanitarian service. Page, a Colorado native, received basic training in Fort Sill, Okla., moved to Fort Bliss in Texas and finished at Fort Bragg in North Carolina.

A psychological operations specialist is "primarily responsible for the analysis, development and distribution of intelligence used for information and psychological effect," according to the U.S. Army website.

[Slideshow: Sikh temple shooting: Images from the scene]

According to the Southern Poverty Law Center, Page "was a frustrated neo-Nazi who had been the leader of a racist white-power band." The band, called End Apathy, formed in 2005. According to the group's MySpace page, its music "is a sad commentary on our sick society and the problems that prevent true progress."

According to the Milwaukee Journal Sentinel, Page is believed to have worked as a truck driver between 2006 and 2010 while living in Fayetteville, N.C. An employee at Barr-Nunn Transportation, the Granger, Iowa-based trucking company Page worked for, said he left "involuntarily" but declined to elaborate.

Law enforcement officials are treating the case as an "act of domestic terrorism," police said, and the FBI is leading the investigation.