Brein Basarich called mass murderer Dylann Roof “precious” and “handsome.” She posted baby pictures of alleged school shooter Nikolas Cruz. She uploaded collages of the 20th century’s most notorious serial killers.

And last week she was arrested for allegedly threatening to kill people herself.

“I had a vision,” she wrote, “of a very public place, only one way in and one way out. Preferably a bar/club on a busy night. 2019 has a lot in store if my plans go according!”

Basarich was part of Tumblr’s “True Crime Community” where serial killers are treated like rockstars and some fans have allegedly turned their fandom into murder plots of their own.

Home to thousands of blogs cataloguing the lives of mass murderers, the TCC draws a motley crowd. Some participants are well-meaning crime researchers. Others sympathize with the popular image of school shooters as tormented loners. And another faction—mostly young women—use the community to recast killers as attractive, desirable celebrities.

Three people associated with the killer-worshipping TCC sect have been arrested over the past month for allegedly planning terror attacks, including Basarich, 31, from Plant City, Florida. Elizabeth Lecron and Vincent Armstrong, both 23 from Toledo, Ohio, were arrested last month for allegedly planning to build pipe bombs and shoot up a bar.

Basarich’s Tumblr was a monument to killers. She didn’t just romanticize them; she appeared to agree with some. She authored two recent posts supporting Roof and attacking African-Americans.

But it was her romantic interest in Roof that made her typical of a large subset of Tumblr’s True Crime Community. She, like Lecron and a sizable population of the TCC world, uploaded posts romanticizing Roof.

Kendra, who asked not to disclose her last name, is a young woman in Tumblr’s True Crime Community. Unlike Basarich and Lecron, she classifies her killer interest as purely academic. She moderates “Serial Killers Aren’t Sexy,” a Tumblr account dedicated to calling out “all the cringe, shitposts, and otherwise garbage of the TCC.”

“From my experience, most of the people in the TCC are younger, probably between 12-20 and are mostly females,” Kendra told The Daily Beast. “I really like true crime and a lot of other people who are in the TCC are also interested in just that, true crime and discussing true crime (and nothing else), but, unfortunately, the TCC has earned a bad reputation thanks to the people who treat it like it's a fandom for serial killers.”

She estimated that some 30 percent of the community shared her general interest in crime, while 70 percent were there to glamorize the killers.

Dave Cullen, the author of books on the Columbine and Parkland high school shootings, has seen this wing of the True Crime Community evolve out of worship for the Columbine killers and into a general movement glamorizing male killers writ large. For years after the Columbine killings, young people tended to dedicate their blogs to a single mass killing, Cullen said. Only in the past five years has he observed the fandoms merging into the current True Crime Community.

The romantic element of the community is “similar to the phenomenon on death row, where women want to marry them or visit them,” Cullen told The Daily Beast. He theorized that the young women worshipping killers on Tumblr believed they could have helped reform the shooters, had they been in a relationship.

“The most common MO I see is the boys wanting to emulate the killers, like ‘I’m the tough guy, I’m gonna kill people’ and the girls more frequently wanting to be the killers’ girlfriends,” Cullen said. Women and girls in the community will frequently post pictures of killers “with heart halos and love poems and all that.”

The killer worship usually stays online. But when it spills over into the real world, the consequences can be catastrophic. Adam Lanza, the man who murdered 20 children and six staffers at Sandy Hook Elementary School in 2012, was a TCC member, The Daily Beast previously reported. He posted pictures of mass shooting victims and video of school shooters on his Tumblr blogs “gayfortimk” and “queerforkimveer,” named for school shooters Tim Kretschmer and Kimveer Gill.

In 2015, three TCC members were busted in a plot to commit a mass shooting at a mall in Halifax, Nova Scotia. The three people—ages 19, 20, and 23—met on Tumblr where all three ran gory blogs that glorified the Columbine murders. A blog by 23-year-old plotter Lindsay Souvannarath had the headline “School Shooter Chic; violence is the aesthetic.” Her blog and that of another plotter are still live, despite Tumblr’s crackdown on other content (specifically nudity).

In December, federal authorities arrested Lecron and Armstrong, the Ohio couple. Both reportedly ran violent Tumblr blogs. Lecron’s blog included graphic pictures of murder victims, and showed a particular affinity for Roof, with pictures of the mass murderer in front of a photoshopped pink Confederate flag, surrounded by hearts. She wrote letters to Roof’s death row prison cell, and was one of only four of his fans to receive a reply, federal authorities said. She allegedly attempted to send him neo-Nazi literature.

After what Armstrong described as “role-playing” that “crossed over” into real-life plans, the couple allegedly plotted mass murder with guns and pipe bombs. They were busted after Lecron purchased bomb ingredients for an undercover FBI officer.

Basarich, meanwhile, was arrested last week after a tip about her Tumblr account. According to an affidavit in her arrest, police in Lakeland, Florida called the 31-year-old into the station after they were tipped off to her post alluding to an attack in “a very public place, only one way in and one way out.”

When another Tumblr user asked whether Basarich had “homicidal urges,” she responded that “I feel at times a lot of us have urges, whether they will admit or not is the question. So yes, I have.” Elsewhere she posted that “I am getting an AR soonish! Pretty excited. It will be my first gun and I plan to get others.”An extended version of the conversation, not included in the affidavit, appears on Tumblr. “What do you need an AR for?” a Tumblr user asked her.

“For shooting,” she replied.

One True Crime Community member called the police.

“We decided to not stay silent and try to find out where she lived and report her to the proper authorities,” the Tumblr user TerminatedTC wrote on the site. That user found Basarich’s real name and location through a Facebook comment she made on a livestream about the Parkland shooter. “Then I called the Lakeland PD and gave them all the information through a phone call and email and now she is off the streets and whatever she was planning to do was stopped.”

Basarich had been on the community’s radar “approximately a week before she'd been arrested,” Kendra, the TCC member who opposes killer worship, said. “We were talking about some of her posts regarding Dylann Roof and the Charleston church shooting.”

Unlike Lecron, who owned guns and allegedly purchased bomb ingredients explicitly as part of a bomb plot, Basarich did not own any weapons, raising the question of whether her posts constituted a legitimate threat or a homicidal fantasy.

“You can never be too sure, honestly,” Kendra said. “You can't really look at a person's online persona and gauge whether or not they're going to genuinely cause harm to someone and that's why the TCC is so dangerous and toxic. I think generally the threats are harmless but it's really hard to tell in a nation where you can just up and buy a gun and shoot someone without warning, you know?”

Cullen characterized most of the community as violent posturing. But that doesn’t make their posts harmless.

“These kids are all posing, trying to act tough,” he said. “But if 99.9 percent of them are posing and know they’re not going to ever do anything, an Adam Lanza among them doesn’t necessarily know that. He sees all these other people who are validating him. He probably thinks they’re all for real.

“That’s the really scary part of this. These other recent cases are probably the same phenomenon.”