The day after long-time white supremacist and anti-Semite Frazier Glenn Miller allegedly opened fire outside two suburban Kansas City Jewish centers, killing three people, he was denounced by the founder of Stormfront.org, one of the Internet’s oldest and largest white nationalist forums.

“We have enough of a problem with how we are portrayed without some homicidal whack job coming along and reinforcing that,” Don Black told The Daily Beast at the time.

But while Black proudly made clear that Miller was never allowed to post on Stormfront, a new study by the Southern Poverty Law Center, a non-profit civil rights advocacy group, shows that Black’s site has hosted its fair share of “homicidal whack jobs.”

According to the SPLC, “registered Stormfront users have been disproportionately responsible for some of the most lethal hate crimes and mass killings since the Web forum became the first hate site on the Internet in 1995, a month before the Oklahoma City bombing.”

Two of the deadliest non-Islamic acts of terrorism in recent years—the 2012 shooting at a Sikh temple in Oak Creek Wisconsin that killed six, and the Norwegian bombing and subsequent shooting on Utoya that killed a combined 77 people in 2011—were carried out by Stormfront users. Over the past five years in particular—since President Obama’s inauguration—active users of the site have been responsible for the murders of nearly 100 people, suggesting that Stormfront is the online breeding ground for right-wing extremist violence.

The revelation that the sole suspect arrested in last weekend’s shootings outside Kansas City was a prominent neo-Nazi, former Ku Klux Klan leader, and frequent commenter on Vanguard News Network (VNN), another anti-Semitic and racist Internet forum, has reignited the long-simmering argument that right-wing extremists are more of a domestic terrorism threat than Islamic extremists. While plenty of attention has been paid to the radicalization of young Muslims online, the SPLC’s study shines a light on the dark corners of the Internet where white, disgruntled racists are transformed into violent extremists.

“Stormfront is the murder capital of the racist Internet,” Heidi Beirich, author of the SPLC report, said in a press release. “It has been a magnet for the deadly and deranged. And VNN is almost as bad.”

Members of hate groups have been meeting and sharing prejudiced ideas online practically as long as the Internet has been around. In a 2001 article about Internet hate speech, the Anti-Defamation League, an international Jewish organization that fights anti-Semitism, suggests that the World Wide Web is the forum of choice for hate groups. “In addition to its multimedia capabilities and popularity with Internet users, the Web allows bigots to control their message,” the ADL explained. It also pointed out that, aside from nationally recognized news sites, it is often difficult for the average Internet user to distinguish between websites that are reputable and those that aren’t.

“Increasingly, Web development tools have made it simple for bigots to create sites that visually resemble those of reputable organizations,” the ADL wrote. “Consequently, hate groups using the Web can more easily portray themselves as legitimate voices of authority.”

Stormfront, specifically, has had a long history of violence among its members. It was during a three-year stint in federal prison for conspiring to overthrow the black government of the tiny Caribbean island of Dominica, and create an all-white state, that founder Don Black learned computer programming. In 1999, four years after the site was created, a regular user named Buford Furrow drove from his parents’ house in Tacoma, Washington to Los Angeles. He shot and injured an elderly woman, a teenager girl and three children at a Jewish day care center before shooting and killing a Filipino-American postal worker. Furrow plead guilty to murder and several hate crime charges and was sentenced to 110 years in prison on top of two life sentences. The following year, 34-year-old Stormfront user Richard Baumhammers went on a racially-motivated shooting spree in Pittsburgh, killing six people, including his 63-year-old Jewish next door neighbor; and painting red swastikas on the outside of a local synagogue and shooting out its windows. In 2002, Ian Bishop, a 14-year-old member of the “Stormfront Youth,” bludgeoned his older brother to death with a hammer, reportedly because he thought he was gay. Bishop was found guilty of third-degree murder and sentenced to 20 to 40 years in prison.

This was just the beginning. The deadliest attacks by Stormfront users wouldn’t take place until after the first black president of the U.S. was inaugurated in 2009. That year, Richard Poplawski killed three Pittsburgh police officers. In 2011, Anders Behring Breivik set off a truck bomb in front of a government building in Oslo, killing eight, and then shot and killed 69 others, mostly teenagers, at a summer camp on Utoya Island. In May 2012, Jason Todd Ready killed four people—his estranged girlfriend, her daughter, her 15-month-old granddaughter, and her fiancé—before killing himself. That same month, a Canadian man named Eric Clinton Kirk Newman, also known as Luca Rocco Magnotta, was accused of torturing and dismembering a Chinese immigrant; three months later, Wade Michael Page shot and killed six people at a Sikh temple before killing himself during a shootout with police.

All of these men, the SPLC says, were active Stormfront users.

The SPLC paints a detailed picture of the person most likely to engage on a hate forum like Stormfront, and most likely to take their aggression, built up over discussion boards, out on people in the real world.

According to the study, “the typical visitor attracted to Stormfront is a frustrated, unemployed, white adult male living with his mother or an estranged spouse or girlfriend. She is the sole provider in the household.” He takes his racist ideologies out into the public domain, attending protests or skinhead concerts or canvassing, and he almost always posts on multiple web forums, escalating from right-wing anti-government sites and conspiracy blogs to militant forums, where he eventually comes to believe that his race is under threat of “white genocide.” As his anger grows, so too does his online history. He discusses guns and violence as the preferred solution to what he perceives to be society’s problems, often antagonizing other forum members and sometimes even getting banned in the month before his violent rampage. The frequency with which he posts varies, either showing a significant increase or decrease in the volume of his posts in the days, weeks, and hours ahead of his killing spree. His writings usually identify an enemy, such as the U.S. government, minorities, or the chimeric Zionist Occupation Government. However, his rampage is triggered by personal events and often takes place in or around his home, where family members might be the first casualties of his rage.

“Assured of the supremacy of his race and frustrated by the inferiority of his achievements, he binges online for hours every day, self-medicating, slowly slipping a cocktail of rage,” writes Beirich in the report. “He gradually gains acceptance in this online birthing den of self-described ‘lone wolves,’ but he gets no relief, no practical remedies, no suggestions to improve his circumstances. He just gets angrier.”

“And then he gets a gun.”

The SPLC’s report offers a startling look at how a website that’s visited by only 1,800 registered members on an average day—less than half of whom live in the U.S.—has managed to produce some of the country’s most devastating incidents of hate-motivated violence in recent years. But the killers who matriculate through Stormfront are only part of a larger issue that deserves renewed attention in the wake of the Kansas City shootings: the pervasive threat of hate crimes, mass murders and domestic terrorism by right-wing extremists.

Hard data on right-wing extremism in the U.S. is hard to come by, ever since the Department of Homeland Security caved under pressure from conservatives to repudiate a leaked 2009 analysis on the subject (PDF), and cut back on studying non-Islamic-related domestic terrorism.

There have been a few recent studies, however, that are in line with the 2009 DHS memo’s warning that economic upheaval coupled with the election of the first black president could lead to increased violence from right-wing extremists. A 2013 report by the Combating Terrorism Center at West Point observed that “there has been a dramatic rise in the number of attacks and violent plots originating from individuals and groups who self-identify with the far-right of American politics.” Last year the liberal website ThinkProgress compiled data from the National Counterterrorism Center, the National Consortium for the Study of Terrorism and Responses to Terrorism, and the SPLC, finding that 56 percent of the domestic terrorist attacks and plots in the U.S. since the 1995 Oklahoma City bombing have been perpetrated by right-wing extremists, while Islamic extremists were only behind 12 percent of them.

Still, DHS has shied away from publicizing these homegrown threats despite such compelling data. In 2011, Daryl Johnson, the former DHS analyst whose team produced the controversial 2009 report, told the SPLC that “Since our report was leaked, DHS has not released a single report of its own on this topic. Not anything dealing with non-Islamic domestic extremism—whether it’s anti-abortion extremists, white supremacists, ‘sovereign citizens,’ eco-terrorists, the whole gamut.”

Though right-wing extremists are considered as much of a fringe minority to mainstream conservatives as Islamic extremists are to mainstream Muslims, racism and anti-Semitism manage to seep into politics in ways that anti-American, Islamist beliefs never could. For a timely example of this, consider the mayor of Marionville, Missouri—Dan Clevenger, a self-described friend of alleged shooter Frazier Glenn Miller who admitted this week that he “kind of agreed with [Miller] on some things, but I don’t like to express that too much.”

“There are some things that are going on in this country that are destroying us. We’ve got a false economy and it’s, some of those corporations are run by Jews because the names are there,” the newly-elected mayor told the local ABC News station. “The fact that the Federal Reserve prints up phony money and freely hands it out, I think that’s completely wrong. The people that run the Federal Reserve, they’re Jewish.”

It’s exactly these kinds of paranoid, baseless and hateful views that draw extremists to Stormfront.org—especially in the immediate wake of an attack. The SPLC points out that according the Web traffic monitoring service Alexa, 4,481 members—a record for the site—were using Stormfront in the 24 hours following the Norway attacks. Stormfront saw one of its most significant spikes in 2012 after the Sikh temple shooting. Apparently profiteering from the publicity surrounding the violence, donations to Stormfront jumped from $6,545 in August 2012, the month during which the shooting took place, to $10,032 that October. And that’s not even counting the money that Black makes from clicks on the site’s banner ads.

According to the SPLC, Stormfront’s membership has gone from 5,000 in January 2002 to 286,000 this year. Though many of these registered users are inactive, these numbers also don’t reflect the large audience of people who read Stormfront threads without posting, which requires registering.

Black has long shirked responsibility for the actions of Stormfront users, telling The Daily Beast earlier this week that, “There have been a few people who have come through that are mentally unstable and went on a killing spree, but their posts didn’t indicate anything like that and they certainly wouldn’t have been tolerated by our moderators if they had.”

But the point the SPLC makes is not that killers are announcing their violent plans on Stormfront. It’s that the forum itself, and the hatred that it fosters, is what pushes someone to stop ranting online and start killing.