Donald Clarke (d. 27 May 1991) was an investigator with the Los Angeles Police Department's Internal Affairs Division, and was partnered with Pierce Lewis. They were known around the Department as Lewis and Clarke.
He and his partner were assigned to open a section 1.81 investigation of LAPD detective Harry Bosch in April of 1990 after Bosch shot and killed Norman Church. They later investigated Bosch again in May of 1991 on the orders of Deputy Chief Irvin Irving. They had an intense dislike for Bosch and the feeling was mutual. Their intent was to have him terminated or even charged with murder. They tailed him almost continuously while he investigated the murders of Billy Meadows and Edward Niese (Sharkey). However, they misunderstood what Bosch was doing, and they believed that Bosch was a participant in the tunnel burglary scheme.