On April 17, Indianapolis’ police chief stepped down after his department botched the handling of evidence in a high-profile case involving one of its own: an officer who may have been legally drunk when he drove his police car into two motorcycles stopped at a red light. The tainted blood sample has fueled allegations of a possible police cover-up in the case.

The Indianapolis incident provides another reminder that there needs to be a wall of separation between forensic science and law enforcement.