For about 10 years now, researchers have been studying both high- and low-performing departments to figure out what goes into a good clearance rate, according to Charles Wellford, who has worked with about 15 agencies.

“In good departments, it is not just clearance. It is, we want to make sure every investigation is done well,” he said. “And to do well, we need a definition of well. We need strong policies and training so people understand what they are supposed to do and (we need) monitoring from supervisors to keep people on track.”

Charles Wellford