Activists in St. Louis are calling for a special prosecutor to handle the case in which a former police officer is accused of killing a man while on duty.

St. Louis Circuit Attorney Jennifer Joyce filed first-degree murder charges Monday against Jason Stockley, more than four years after the shooting death of Anthony Lamar Smith in December 2011.

The St. Louis Post-Dispatch reports that activists on Thursday complained that Joyce and U.S. Attorney Richard Callahan couldn't be trusted because it took so long to file charges.

Joyce says in a statement that her office had no investigative role until March. Callahan's office declined to prosecute after examining evidence in 2012 and referred the case to the U.S. Department of Justice. The Justice Department civil rights review remains open.

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