MILWAUKEE – When they aren't ranting in Internet forums, many of the nation's white supremacists seek a louder outlet for their extreme views: thunderous, thrashing heavy metal or punk with lyrics that call for a race war.

Wade Michael Page, the gunman who killed six people at a Sikh temple in Wisconsin before being killed by police, was deeply involved in the "hate rock" scene – a shadowy world of hundreds of performers in the U.S. and Europe, most of them playing metal or hardcore punk. Some also play country, folk and other genres.

Largely unknown to most Americans, this musical subculture is an integral part of neo-Nazi circles, offering a way for like-minded followers to connect with each other and socialize, recruit new members and raise money for their cause.