Four officers with the St. Louis Police Department have been criminally charged in the alleged beating of an undercover officer working the scene of a protest following the acquittal of former police Officer Jason Stockley, who was accused of first-degree murder related to the shooting death of a civilian.

According to the Washington Times, Officers Dustin Boone, Randy Hays, and Christopher Myers, slammed the undercover officer to the ground, kicked him and beat him with a police baton, federal prosecutors said.

A fourth officer—25-year-old Bailey Colleta—is accused of lying to a federal grand jury investigating the incident.

The victim in this case was identified only as L.H.—a 22-year veteran of the force.

The three officers accused of beating the officer face charges of willfully violating L.H.'s constitutional rights. If convicted, all four could face up to 20 years in prison.