Ep 20. Season 4, Episode 7: "High Top Fade Out"

James and Dulé's Pick: Leonard "Diddle" Callahan (Demond Dann), a college friend of Gus is chased by armed assailants and when he reaches his apartment building, drops his bike and runs inside. Before the men break in and asphyxiate him Diddle pulls a digital camcorder from his backpack and is able to email out its contents. Shawn and Gus attend Diddle's funeral where Shawn discovers that Gus was in a singing group with Diddle and their other friends Tony (Jaleel White) and Joon (Kenan Thompson), but he has been estranged from them for years and refuses to say why. When Tony and Joon are able to speak to Shawn alone they tell him Diddle was way too careful on his bike to die in an accident. They believe he was murdered, and they hire Shawn to find out what happened.