Mark Estes of the popular TikTok group the Montana Boyz was accused of felony federal assault in February 2021 after allegedly beating up a group of students, Page Six has exclusively learned.

A spokesperson for the Gallatin County Sheriff’s Office confirms the influencer – who is now dating “Hills” alum Kristin Cavallari – was involved in the violent incident three years ago, which led to the hospitalization of one of the alleged victims. Estes, 24, was ultimately never charged.

We’re told Estes – who was a student at Montana State University at the time – and his friends allegedly got into a brawl with another group of students in an off-campus fight.

However, by the time law enforcement arrived at the location, everyone was “gone and separated,” which is why no immediate arrests were made.

A Gallatin County Sheriff’s Office public information officer, who worked on the case, tells Page Six that police were not informed of the incident until the injured parties were already at the hospital.

He notes, however, that the group who fought Estes and his pals were at the hospital for just one person, though the entire group seemingly went to support their injured friend.

“If we’re coming to those kinds of things after the fact, we might not arrest the person even if there’s probable cause for them to be charged,” the officer explains.

“We’ll put in what’s called a request for prosecution at the County Attorney’s Office, and they will either issue a warrant or a summons if they feel that probable cause exists to continue on with the case.”

The officer on the case says he pursued a request for prosecution for Estes in particular because this was not a situation in which the then-student athlete was at the wrong place at the wrong time, alluding to the fact that the TikTok personality was allegedly one of the aggressors.

“I put in the request that Mark Estes be charged with aggravated assault and misdemeanor assault because there were two victims,” the officer says.

“I felt that there was probable cause [because] one person’s injuries sustained rose to the level of aggravated assault. The other person who was involved, his injuries were significantly less, just minor scrapes and bruises, which is more of a misdemeanor charge.”

Despite the officer’s requests, Page Six learned that the Gallatin County Attorney’s Office ultimately decided not to press charges against Estes or others involved because they felt it was “mutual combat.”

We’re told no charges were filed against the other parties, and the status of the injured student’s health was not revealed due to it being “private medical information.”

The public information officer notes, though, that there were “some penalties that Montana State imposed” since Estes and the other parties involved were students at the university at the time.

Michael Becker, a rep for Montana State University, declined Page Six’s request to comment on the situation, stating, “Matters concerning individual students’ discipline are protected by federal privacy law.”

According to online records, it appears that Estes transferred schools shortly after the incident. However, it’s unclear whether the incident had anything to do with his move.

He appeared in Montana State’s football roster in 2020 but by 2023 he was playing for Montana Tech.

In recent years, Estes has rose to prominence on social media for his lip-synching videos with pals Kaleb Campbell Winterburn and Kade Wilcox.

The trio boasts more than 800,000 followers on TikTok and nearly 400,000 followers on Instagram.

“The boys began posting on TikTok and in a matter of weeks became viral for their good looks and country flair,” a spokesperson for the group recently told us in a press release.

“Former college football stars, these guys are more than just athletes — they’re models and cowboys, balancing ranch life with the stardom of social media. They seamlessly blend the rugged allure of cowboy life on the ranch with the polished finesse of fashion, crafting a unique persona that captivates audiences.”

Estes, for his part, has garnered even more fame for his romance with Cavallari.

The social media personality and 37-year-old “Laguna Beach” alum – who have a 12-year age gap – went public with their relationship in February. They are reportedly getting “pretty serious” and he has met her kids, whom she shares with ex-husband Jay Cutler.

Page Six has reached out to a rep for Cavallari for comment on her boyfriend’s alleged criminal background but did not immediately hear back.

The Gallatin County Sheriff’s Office also confirms to Page Six that neither Winterburn nor Wilcox’s names appear on the February 2021 assault case files.

However, Page Six obtained video that shows Winterburn’s track record is not squeaky clean, either.

In the clip, the TikToker appears in the front seat of a car – with Estes beside him in the front-side passenger’s seat and another friend fooling around in the back of the vehicle.

Winterburn then says into the camera while looking at the friend behind him, “Hey, Seth. You’re a n–r,” prompting Estes’ jaw to drop before the video cuts off.

Page Six has reached out to reps for the Montana Boyz for comment but did not immediately hear back.