BUSTED: Four St Louis cops charged by feds for beating up undercover colleague during police brutality protest

A group of St. Louis police officers were hit with federal charges after beating up their undercover colleague during a protest -- and then covering it up.

The St. Louis Post-Dispatch reported that three members of the St. Louis Police Department knocked a 22-year police veteran to the ground, kick him and hit him with a baton -- all while he was "compliant and not posing a physical threat," prosecutors alleged.

STPD officers Dustin Boone, Randy Hays and Christopher Myers were accused of the physical assault on the undercover cop and Officer Bailey Colletta was accused of lying to a federal grand jury about it.

The alleged assault took place during a September 2017 protest against the acquittal of the white former STPD officer Jason Stockley who shot and killed Anthony Lamar Smith, a 24-year-old black man, in 2011.

In the federal indictment, text message exchanges between the officers show them expressing "disdain" for the anti-police brutality protesters, as well as "excitement about using unjustified force against them and going undetected while doing so."

"Let's whoop some ass," Myers wrote in a September 2017 text sent days before the incident.

"It's gonna be a lot of fun beating the hell out of these (expletive) once the sun goes down and nobody can tell us apart!!!!" Boone wrote in one text message before the alleged beating on September 17. In another sent the same day as the protest, the officer said that it was "a blast beating people that deserve it."

The indictment noted that the three officers involved in the alleged assault lied about the police veteran they beat up once they learned he was undercover, claiming he had resisted arrest and was not compliant. They also allegedly tried to " contact the officer to dissuade him from pursuing disciplinary or legal action."

Read the entire story via the St. Louis Post-Dispatch.