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.

A day after he killed six worshippers at the suburban Milwaukee temple, fragments of Page's life emerged in public records and interviews. But Oak Creek Police Chief John Edwards said Monday that investigators might never know why the lone attacker chose his target.

"We have a lot of information to decipher, to put it all together before we can positively tell you what that motive is — if we can determine that," Edwards said.

The attacker entered the temple about 10:15 a.m. Sunday, police officials said, and began firing at religious leaders in the lobby.

He then stalked through the temple as congregants, including women preparing a meal for services, ran for shelter and barricaded themselves in bathrooms and prayer halls. They made desperate phone calls and sent anguished texts pleading for help.

The first police officer on the scene was tending to a wounded person in the parking lot when the suspect stood over him and fired eight or nine shots at close range, striking him in the neck.

The officer, Lt. Brian Murphy, 51, was in critical condition after surgery. Murphy was a 21-year veteran of the department. He waved on officers trying to assist him in the parking lot, telling them to go into the temple to check on victims there.

Officers spotted the suspect in the parking lot and ordered him to drop his weapon. He responded by firing at patrol cars, shattering a windshield. Edwards said the officers "returned fire, putting the individual down."

Federal officials said the gun used in the attack had been legally purchased. Page was issued five pistol-purchase permits in 2008 in North Carolina, paying a $5 fee for each.

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.

Page wrote frequently on white-supremacist websites, describing himself as a member of the "Hammerskins Nation," a skinhead group rooted in Texas, according to the SITE Monitoring Service, a Maryland-based private intelligence firm that searches the Internet for terrorist and extremist activity.

In online forums, Page promoted his music while interacting with other skinheads. He posted 250 messages on one site between March 2010 and the middle of this year, and appeared eager to recruit others. In March 2011, he advertised for a "family friendly" barbecue in North Carolina.

In November, Page challenged a poster who indicated he would leave the United States if Herman Cain were elected president, writing in reply, "Stand and fight, don't run."

Mark Potok, a senior fellow at the law center, a nonprofit civil-rights organization in Montgomery, Ala., said Page played in groups whose music talked about genocide against Jews and other minorities.

Page joined the military in Milwaukee in 1992. As a "psy-ops" specialist at Fort Bragg, N.C., Page would have trained to host public meetings between locals and American forces, use leaflet campaigns in a conflict zone or loudspeakers to communicate with enemy soldiers.

He never deployed overseas in that role, Army 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.

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, Texas, for getting drunk and kicking holes in the wall of a bar.

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

In Wisconsin, Page responded to a recent online ad seeking a roommate in Cudahy, a small city outside Milwaukee. He rented a room in Kurt Weins' house in June, telling Wein he had recently broken up with his girlfriend and needed a place to stay.

Several weeks later, Page rented an apartment in a duplex owned by Weins across the street. Page explained that he wanted to bring some belongings out of storage.

Suburban Milwaukee police had no contact with Page before Sunday.

The FBI was leading the investigation because the shooting was considered domestic terrorism. The agency said it had no reason to believe anyone other than Page was involved.

The president of the temple died defending the house of worship he founded.

Satwant Singh Kaleka, 65, managed to find a simple butter knife in the temple and attempted to stab the gunman before being shot twice, his son said Monday.

Amardeep Singh Kaleka said FBI agents told him his father was a hero.

"Whatever time he spent in that struggle gave the women time to get cover" in the kitchen, Kaleka said.

Other victims were identified as Sita Singh, 41; Ranjit Singh, 49; Prakash Singh, 39; Paramjit Kaur, 41; and Suveg Singh, 84.

Associated Press writers Gretchen Ehlke and Dinesh Ramde in Milwaukee; Michael Biesecker in Fayetteville, N.C.; Patrick Condon in Minneapolis; Danny Robbins in Dallas; and Pauline Jelinek and Eileen Sullivan in Washington contributed to this report, along with the AP News Research Center in New York. Contains material from The New York Times and The Washington Post