ST. LOUIS (AP) — Four St. Louis police officers accused of wrongfully beating or helping cover up the beating of an undercover colleague during 2017 protests are set to go to trial this year.

A  judge on Friday set a trial date of Dec. 2 for Dustin Boone, Randy Hays, Christopher Myers and Bailey Colletta. Boone, Hays and Myers are accused of assaulting Officer Luther Hall, who was working undercover during a protest downtown at the time. Myers is also accused of destroying Hall’s cellphone. Colletta is accused of lying to a federal grand jury investigating the attack. All have pleaded not guilty.

Court documents say the officers mistook Hall for a protester on Sept. 15, 2017, following the acquittal of a former St. Louis police officer on a murder charge. Hall described the attack in court documents as a “free for all” and suffered several herniated discs and a jaw injury.