Psych: Season 3, Episode 11

3 - 11: Lassie Did a Bad, Bad Thing

Lassiter has never liked the presence of Shawn and Gus since they became consultants in solving cases, but he finds himself in need of their help when he is the main suspect in a murder committed in his own precinct. Shawn is already certain that Lassiter is not guilty, and deduces that the killing was an inside job.