Updated 6:18 p.m. ET

The mug shot handed out by the FBI of the suspect Wade Michael Page after a press conference on the shooting at the Sikh Temple of Wisconsin where a gunman fired upon people at service August, 6, 2012 in Oak Creek, Wisconsin. CBS/FBI via Getty Images

(CBS/AP) OAK CREEK, Wis. - Before he strode into a Sikh temple with a 9 mm handgun and multiple magazines of ammunition, Wade Michael Page played in white supremacist heavy metal bands with names such as Definite Hate and End Apathy.

The bald, heavily tattooed bassist was a 40-year-old Army veteran who trained in psychological warfare before he was demoted and discharged more than a decade ago.

When the shooting at the Sikh Temple of Wisconsin in suburban Milwaukee ended, six victims ranging in age from 39 to 84 years old lay dead. Three others were critically wounded, including Oak Creek Police Officer Lt. Brian Murphy.

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Page was shot and killed by 32-year Oak Creek Police veteran Sam Lenda on scene.

Lt. Brian Murphy, one of the police officers who ran to the scene of the shooting of a Sikh temple in Wis., was critically injured. Milwaukee County Sheriff's Office

A day after the shooting, fragments of Page's life emerged in public records and interviews. But his motive was still largely a mystery. He left no hate-filled manifesto, no angry blog or ranting Facebook entries to explain the attack.

Page joined the Army in 1992 and was discharged in 1998. He was described Monday by the Southern Poverty Law Center as a "frustrated neo-Nazi" who had long been active in the obscure underworld of white supremacist music.

Mark Potok, a senior fellow at the nonprofit civil rights organization in Montgomery, Ala., said Page played in groups whose sometimes sinister-sounding names seemed to "reflect what he went out and actually did." The music often talked about genocide against Jews and other minorities.

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In a 2010 interview, Page told a white supremacist website that he became active in white-power music in 2000, when he left his native Colorado and started the band End Apathy in 2005.

Bystanders stand outside the scene of a shooting inside The Sikh Temple in Oak Creek, Wis, Sunday, Aug. 5, 2012. JEFFREY PHELPS

He told the website his inspiration was "based on frustration that we have the potential to accomplish so much more as individuals and a society in whole," according to the law center. He did not mention violence.

End Apathy's MySpace page said the group was based in Nashville, N.C.

Joseph Rackley, who lives in Nashville, said Monday that Page lived with his son for about six months last year in a house on Rackley's property.

"I'm not a nosy kind of guy," Rackley said. "When he stayed with my son, I don't even know if Wade played music. But my son plays alternative music, and periodically, I'd have to call them because I could hear more than I wanted to hear."

Page joined the military in Milwaukee in 1992 and was a repairman for the Hawk missile system before switching jobs to become one of the Army's psychological operations specialists assigned to a battalion at Fort Bragg, N.C.

As a "psy-ops" specialist, Page would have trained to host public meetings between locals and American forces, use leaflet campaigns in a conflict zone or use loudspeakers to communicate with enemy soldiers.

He never deployed overseas while serving in that role, Pentagon spokesman George Wright said.

Page was demoted in June 1998 for getting drunk while on duty and going AWOL, two defense officials said, speaking on condition of anonymity because they were not authorized to release information about the gunman.

Page also received extra duty and was fined. The defense officials said they had no other details about the incident, such as how long Page was gone or whether he turned himself in.

Outside Fayetteville, N.C., a brick ranch house Page bought in 2007 with help from a Veterans Administration mortgage stood boarded up Monday with knee-high weeds in the yard. A notice taped to the front indicated the home was in foreclosure and had been sold to a bank in January.

Before buying the home, Page lived with Army soldier Darren Sherlock, his wife and young children in a doublewide trailer in a rural community near Fort Bragg, records show.

Sherlock, dressed in his military fatigues, declined to comment about Page or the shooting when approached Monday by The Associated Press.

Back in Wisconsin, Page responded to a recent online ad seeking a roommate in Cudahy, a small city outside Milwaukee.

Kurt Weins, who placed the ad, said Page moved in June 23 with only a television set, telling him he had recently broken up with his girlfriend and needed a place to stay.

"We talked, but it was really about nothing," Weins said. "He seemed pretty calm. He didn't seem like the type to raise his voice."

On July 15, Page moved to a duplex across the street. After the FBI searched that residence Sunday, Weins said he returned to the apartment and found only a computer desk, chair and an inflatable mattress.

Peter Hoyt, who lives about a block from Page's last apartment, said he spoke with Page about a dozen times. Hoyt remembered Page having a "9/11" tattoo on his arm but could not describe it.

"I never heard the guy ... say anything negative," Hoyt said. "When I found out it was him, I was awed. I can't believe it was him."

Online records show Page had a brief criminal history in other states, including pleading guilty to misdemeanor criminal mischief after a 1994 arrest in El Paso. He received six months' probation. Page also pleaded guilty to driving under the influence in Colorado in 1999 but never completed a sentence that included alcohol treatment, records show.

Suburban Milwaukee police had no contact with Page before Sunday, and his record gave no indication he was capable of such intense violence.