Retirement Is Murder
S2, E13: While Martin continues with his 20-year obsession with solving a murder, Frasier decides to step in with his own solution: that the murderer was, in fact, a monkey.

S2, E13: While Martin continues with his 20-year obsession with solving a murder, Frasier decides to step in with his own solution: that the murderer was, in fact, a monkey.