by James Bandler, ProPublica, A.C. Thompson, ProPublica and FRONTLINE, and Max Maldonado, FRONTLINE

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Early last year, Matthew Allison could be found at the Space Banana dance club, awkwardly swaying to his own beat. Clutching the cheapest house beer, he’d greet people with a bear hug, a broad grin and his familiar, “Yo, bro!” salutations.

Allison, then a 37-year-old convenience store worker and Saturday-night DJ, seemed to like everyone he met in Boise, Idaho’s small electronic dance music scene. And most people seemed to like him back.

He was so gentle, former friends remember, that for a time he eschewed honey so as not to cause harm to bees.

He was “a little goofy,” a former friend, Tyler Whitt, recalled. “But bro goofy.”

But that lovable persona hid a more sinister core. When he was behind his computer screen, Allison used the handle BTC, short for BanThisChannel, he told ProPublica and FRONTLINE. On the social media and messaging platform Telegram, authorities say, Allison was a key figure in a network of white supremacist and neo-Nazi chat groups and channels known as Terrorgram.

There, Allison held court, promoting himself as “the most infamous and prolific propagandist of our time.”

Hyperbole aside, BTC was infamous. Extremism researchers in the U.S. and in Europe studied his posts but did not know who he was. Leftist activists sought to expose him. And law enforcement authorities tried to identify and jail him.

Last September, he was finally arrested.

Prosecutors allege that Allison was one of the leaders in the Terrorgram Collective, a secretive group that produced propaganda and instructions for terrorists, and disseminated that information through the Terrorgram ecosystem.

They say Allison used the Telegram platform to solicit “attacks on government infrastructure, such as government buildings and energy facilities,” to encourage the assassination of “‘high-value targets’ — like politicians and government officials” with a “hit list,” and to help produce and distribute a Terrorgram Collective publication that featured instructions for making “Napalm, thermite, chlorine gas, pipe bombs, and dirty bombs.”

This story is part of a collaborative investigation from ProPublica and FRONTLINE that includes an upcoming documentary, “The Rise and Fall of Terrorgram,” which premieres March 25 at 10 p.m. EDT/9 p.m. CDT on PBS stations (check local listings) and will be available to stream on YouTube, the PBS App and FRONTLINE’s website.

Authorities also contend in court filings that Allison had fantasies about committing gruesome violence and sexual assault, and that he may have been planning to act on them.

Allison has pleaded not guilty.

For about five years, the Terrorgram network operated largely unchallenged on Telegram, which has nearly one billion users. The Dubai-based company did little to prevent influencers like Allison from circulating their propaganda and encouraging isolated young men to kill, a ProPublica and FRONTLINE investigation found.

The news organizations obtained a trove of now-deleted Telegram chats and channel logs and used them to trace Allison’s activity and influence in the Terrorgram network.

Telegram has declined repeated requests to make its executives available for interviews but said in a statement, “When the Terrorgram name first surfaced years ago, we began removing groups and channels that used variations on the Terrorgram name. Calls for violence from any group are not tolerated on our platform.”

In the annals of white supremacist content online, Allison’s work stood out. “It was some of the most inflammatory propaganda that I had seen,” said Jennefer Harper, a researcher who has amassed a large archive of neo-Nazi materials from Telegram. Allison was also prolific. “This propaganda was being posted 24/7! The account wasn’t taking a break, it was like, ‘Don’t you have anything else to do in your life?’”

He specialized in what he called documentaries, and over more than five years, he said, he made and posted around 120 videos. There were images of riots, burning cities and Black people brutalizing white people. There was GoPro footage of massacres filmed by white killers as they murdered people of color.

Allison and the other Terrorgram leaders found a receptive audience for their propaganda. Some of their fans got off their phones and took action: scoping out high-profile targets and even killing people. ProPublica and FRONTLINE used the chat logs, court records and other sources to connect 35 criminal cases to the Terrorgram network. Each case involved an individual who posted in Terrorgram chats, followed Terrorgram accounts or was a member of an organized group whose leaders participated in the Terrorgram community.

Prosecutors have linked Allison and his co-defendant, Dallas Humber, to a trio of mass shootings that killed a total of six people and wounded a dozen others, and to a stabbing incident that injured five, according to the indictment and a subsequent brief.

In early 2024, Allison’s work caught the attention of a young man from New Jersey named Andrew Takhistov.

Takhistov was in a Terrorgram group chat in which someone had posted several Allison videos, including a 51-second clip showing how to disable overhead electrical........

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