A Texas prosecutor has dropped indictments against 17 Austin police officers who were charged with assault after being accused of injuring demonstrators during the 2020 George Floyd protests, and city officials are asking the US Justice Department to investigate possible police misconduct within the department.

Travis County District Attorney José Garza requested the federal probe after his office’s investigation into the Austin Police Department officers’ actions “revealed problems within the department that cannot be corrected by criminal prosecutions alone,” the prosecutor’s office said in a social media post on Monday.

The May 2020 demonstrations in Austin were part of a nationwide movement against police brutality in the wake of Floyd’s death, which was captured on video and showed a Minneapolis police officer kneeling on Floyd’s neck as he pleaded for help.