Kathy Willowby killed her husband, Martin Willowby, in Mr. Monk Gets Cabin Fever. During a stormy night while Martin was taking a a bath, she tossed an electric radio into the bathtub, killing him instantly. Later, she dressed her husband in fishing gear, placed him in his row boat, and sent him off into the lake dressed as a fisherman with a burnt patch on the boat. She then claimed that lightning killed her husband so that she could collect his insurance money.
Arrest[]
Adrian Monk figured out that Kathy had murdered her husband. For starters, her husband was missing a lucky fishing lure he had bought previously in the episode and he was not taking the precautions that a fisherman would during a storm.
After Monk went into her house to question her, he noticed that there was some burnt wiring leading to the bathtub. He put all the facts he had together. First, he heard a scream on the night Kathy's husband was murdered. Second, the missing lure on the boat, and, third, the burnt wiring leading to the bathtub. She was arrested by Leland Stottlemeyer and sentenced to jail.