In the season five episode "Mr. Monk Gets a New Shrink", he temporarily retires when he finds his cleaning lady Teresa Mueller stabbed and killed in his office, and the police believe that one of his patients is responsible.
In the season five episode "Mr. Monk Gets a New Shrink", Dr. Kroger finds his cleaning lady Teresa Mueller stabbed and killed in his office. He retires out of guilt as the police believe that one of his patients is responsible.