Nearly 100 murders around the world in the last five years, including those of Sikh worshippers in the US in 2012, can be traced back to users of the biggest white supremacist forum on the Internet, a hate-group watchdog has said.
The majority of those killings were committed by Anders Behring Breivik, the Norwegian extremist best known for the massacre of 69 people, most of them teenagers, at a summer camp outside Oslo in 2011.
But, in common with other killers, he frequented Stormfront.org, which the Southern Poverty Law Center (SPLC) branded a "racist forum" in a study that comes on the heels of Sunday's triple murder at two Jewish sites in Kansas.
Stormfront's users have included Wade Michael Page, who killed six people and then himself at a Sikh gurudwara in Wisconsin in 2012, and Buford O'Neil Furrow, who shot and wounded five people at a Jewish day care center in Los Angeles in 1999 before killing a Filipino-American postal worker.
"Stormfront is really a worldwide enterprise," said Heidi Beirich, who authored the report for the Alabama-based non-profit organization that monitors homegrown extremist groups in the United States.
Such websites, added Beirich in a conference call with reporters, serve as virtual "breeding grounds for people just enraged by their situation." Frazier Glenn Cross, 73, also known as F Glenn Miller, who has been charged with murder for the Kansas rampage, frequented another site, Vanguard News Network, posting more than 12,000 times.
Launched in 1995, Stormfront -- motto, "White Pride, World Wide" -- has 286,000 registered users, though on any given day fewer than 1,800 log on to the site, most of them from outside the United States, the SPLC said.
Not all the homicides were race-related: the report mentioned two Stormfront users who shot and killed their wives and then themselves, as well as an "aspiring skinhead" who gunned down three Pittsburgh police officers in 2009.
More often than not, the perpetrators have been frustrated, unemployed white adult males, living with their mothers or an estranged mother or girlfriend, who "binges online for hours" on militant hate sites.
Breivik, who claimed Norway was being invaded by Muslims, was a registered Stormfront member for three years, introducing himself in 2008 with the username "year2183," the SPLC said.
He is serving a 21-year sentence for the summer-camp shooting and a bomb attack on a government building in which eight people died.
"Registered Stormfront users have been disproportionately responsible for some of the most lethal hate crimes and mass killings" since its launch by Don Black, a one-time Klan leader in Alabama, said the study.