Three St. Louis police officers were indicted on Thursday for allegedly beating a fellow officer who was undercover in a crowd protesting the 2017 acquittal of the white officer who shot and killed Anthony Lamar Smith.

The three are also accused of conspiring to cover up the beating, and a fourth officer is charged with lying to a federal grand jury to help in the cover-up, according to the St. Louis Post-Dispatch. The three officers have been identified as Dustin Boone, Randy Hays, and Christopher Myers. The fourth, Bailey Colletta, denied knowing the victim and said he was “brought to the ground very gently” the night of his arrest.

But in reality, the victim—identified by the Post-Dispatch as Luther Hall, a black man and 22-year veteran of the force—had been beaten so severely he could not eat and lost 20 pounds, according to prosecutors. The officers threw Hall to the ground, kicked him, and beat him with a police baton, prosecutors said. The Post-Dispatch described a cut above his lip as a “2-centimeter hole that went through his face.” Hall had surgery to repair two herniated discs in his neck and back, and more than a year after the incident, he still has been unable to return to work.

The alleged assault took place after officer Jason Stockley was acquitted of murder on Sept. 15, 2017. Stockley had killed the 24-year-old Smith in 2011 after an alleged drug deal, shooting him five times after a high-speed chase. Stockley carried an unauthorized, personal AK-47 during the confrontation and was heard in a recording saying “we’re killing this motherfucker.” After the acquittal, protests erupted for days around St. Louis, including a large protest on Sept. 17, the night of Hall’s assault.

According to the Post-Dispatch, court records show the three officers accused of the beating had exchanged gleeful texts after Stockley’s acquittal was announced. They expressed excitement about the prospect of attacking protesters. Myers, who had been with the department for three years, wrote, “let’s whoop some ass.” Boone texted, “It’s gonna get IGNORANT tonight!!” He added: “It’s gonna be a lot of fun beating the hell out of these shitheads once the sun goes down and nobody can tell us apart!!!!”

In follow-up texts after the protest, the officers made it clear they had enjoyed their police work that night. On Oct. 5, 2017, Hays, an eight-year member of the force, texted, “going rogue does feel good.”

But after they learned they had assaulted a colleague, according to the prosecutors, they lied about the arrest, claiming the victim had not been compliant. They also reached out to Hall to discourage him from taking any action in response to the incident, and Myers allegedly destroyed Hall’s phone in an attempt to thwart a federal investigation. (Police Chief John Hayden said he requested help from the FBI after learning about the allegations).

The three officers have been charged with depriving Hall of his constitutional rights as well as conspiring to obstruct justice. Myers is also charged with destruction of evidence. They could face up to 20 years, but they are expected to get a less severe punishment if convicted, based on federal sentencing guidelines.

The protests that night led to a number of federal lawsuits. Police that night were accused of indiscriminately arresting a large number of people at the scene—including journalists— and using the controversial “kettle” tactic of crowd control in a way that several lawsuits asserted violates Fourth and Fourteenth Amendment rights to be free from unlawful seizure (on top of First Amendment rights of assembly and expression). Police, who have said some protesters were aggressive and resisted orders while blocking streets, also used pepper spray as they arrested more than 80 people. Witnesses at the scene reported police shouted the protest chant “Whose streets? Our streets!” as they made their arrests.