“No questions asked, they literally knew about posts that hinted HEAVILY at a school shooting, even admitting it in a tweet,” the user wrote. Raw Story linked the account flagged to the FBI to Henderson as it is included on a list of his social media accounts in a manifesto that he posted online in advance of his own attack.
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The FBI declined to comment in response to emailed questions from Raw Story about whether the agency followed up on the tip.
A social media account connected to Henderson may have been in contact with Rupnow’s social media account, ABC News reported, citing unnamed law enforcement sources.
An archived log of the X account flagged to the FBI, which is now suspended, used Rupnow’s photo as his profile picture in apparent homage.
“They think we’re satanic pdf groomers,” one post from the account reads. “Part of super Mkultra cult making kids kill. They [sic] people are f---ing stretching. I’m just trolling. I barely know her.”
In another post, the account connected to Henderson complained: “Feds will arrest random teenagers but not actual criminals.” Later, the user wrote: “Who knows I may get [a] visit. I’ll record if anything happens.”
It wasn't immediately clear whether the FBI talked to Henderson.
Before carrying out her attack on Dec. 16, Rupnow posted a photo on X that framed her pantlegs and black boots with her feet planted on a bathroom floor. Henderson similarly posted a series of photos on X on Wednesday that showed his pantlegs and boots from the same angle. One of Henderson’s photos showed an open backpack between his legs that was opened to display a handgun.
While using a cell phone to livestream the attack, Henderson walked from the bathroom into the cafeteria at Antioch High School and opened fire. Henderson killed 16-year-old Josselin Corea Escalante, described by her father as a kind and loving girl who played soccer and brought home good grades, and injured another student. Like Rupnow, Henderson died from a self-inflicted gunshot wound.
Henderson and Rupnow both identified with incel — short for involuntary celibate — a violent extremist movement that is focused on hatred of women specifically and humanity in general, as a response to a perception that they are romantically and sexually undesirable. They both also expressed support for white supremacy and national socialism, although Henderson was Black.
In a manifesto posted online hours before the Wednesday attack, Henderson paid tribute to numerous white supremacist mass murderers, including Anders Breivik, Brenton Tarrant and Payton Gendron. He recommended tactical manuals produced by the Terrorgram Collective, which the U.S. State Department named earlier this month as a specially designated global terrorism entity.
Henderson also said in the manifesto that he had been inspired by Rupnow, along with four other so-called “new gen” attackers, adding that he had “connections with some of them only loosely via online messaging platforms.”
Marc-André Argentino, a senior researcher at the Accelerationism Research Consortium, wrote in a blog post that Henderson’s “social network behavior indicates an individual who is not only part of the true crime community, but an individual who was in touch with past school shooters” such as Rupnow.
Argentino wrote that Henderson’s diary and manifesto “together outline a blend of personal despair, terrorist and violent extremist content, and rigorous planning,” while his documentation “offers a sobering reminder of how swiftly digital subcultures and the trauma inducing content of these sadistic ecosystems can radicalize youth into an imminent threat.
This story has been updated to reflect that the FBI declined to comment in response to questions about whether the agency followed up on a tip about Solomon Henderson's X account prior to his deadly attack at Antioch High School on Wednesday.
