FBI says it was tipped off to social media account now connected to Colorado school shooter in July

The FBI said on Monday that it received a tip about a social media account, which has since been connected to the Evergreen High School shooter, two months before he shot two students and then himself in the Denver area school.

An FBI spokesperson said the bureau opened an "assessment" into the social media account, which posted "non-specific" threats of a mass shooting but didn't know the account-holder's identity.

The shooter, identified by the Jefferson County Sheriff's Office as 16-year-old Desmond Holly, died of a self-inflicted gunshot wound, according to the sheriff's office. The FBI says it didn't know the identity of the account holder and, as a result, there was no probable cause for anyone's arrest.

"In July 2025, the FBI opened an assessment into a social media account user whose identity was unknown and who was discussing the planning of a mass shooting with threats non-specific in nature. The FBI reviews all tips and pursues credible leads, and allegations of criminal conduct are reviewed for their merit with consideration of any applicable federal laws. We continued to work this assessment investigation to identify the name and location of the user up and until September 10, 2025. During the assessment investigation, the identity of the account user remained unknown, and thus there was no probable cause for arrest or additional law enforcement action at the federal level," the FBI told CBS News Colorado in a written statement on Monday.

The shooter was active on a so-called "violent gore" site months before the attack, the Anti-Defamation League said in a report released Friday. The Jefferson County Sheriff's Office said he had been "radicalized by an extremist network," but didn't provide further details. The website that the Evergreen High School shooter was active on was also frequented by other recent school shooters, the ADL told CBS News. The Jefferson County Sheriff's Office said it cannot comment as the investigation remains open.

"The ADL Center on Extremism regularly shares alerts and updates with law enforcement. We shared profiles and activity at the time with law enforcement for actions they deemed necessary based on what was available at the time," Oren Segal, senior vice president of counter-extremism and intelligence at the ADL, told CBS Colorado in a statement on Monday. "We have since learned those profiles belonged to the individual responsible for the shooting in Evergreen."

The 16-year-old posted a photo of himself holding a gun next to a box of ammunition on his X account two hours before the shooting, CBS News reported on Sunday. He also showed his collection of tactical gear, which featured extremist symbols. In a since-deleted TikTok post that contained references to a 2019 mass shooting at a mosque in Christchurch, New Zealand, he engaged with a comment encouraging him to "make a move," according to the ADL.