From March 2010 to earlier this year, Page posted 250 times on supremacist sites, according to SITE Intelligence Group, a watchdog that monitors extremist activity online.
Many of those posts, written under the screen name Jack Boot or End Apathy, the name of his band, were invitations to white-supremacist gatherings where his band played.
But over time, some posts called for action beyond just complaining on the Internet.
"Stop hiding behind the computer or making excuses," he wrote last year, a chilling foreshadow to Sunday's shooting.
"Passive submission is indirect support to the oppressors. Stand up for yourself and live the 14 words," he wrote in April, referring to the neo-Nazi mantra.
Page entered the Sikh Temple of Wisconsin on Sunday morning as members were preparing for prayers and began shooting.
He left six people dead and several wounded, including an Oak Creek, Wis., police officer, before he was shot dead.