The Mentalist Season 4 Episode 20
Something's Rotten In Redmund
-Jack McTierney, a high school teacher is found dead on the baseball field.
-Jane finds out that the Principal has secret cameras in the bathrooms and he and Grace go through all of the video. Jane notices Billy pulling the same leaves off of his clothes that he saw on Mrs. Austin, the drama teacher.
-Jane insinuates himself into the high school production of Hamlet in order to reveal the killer as Mrs. Austin. She was having an affair with 16 year old Billy. When Jack found out he threatened to expose her and she killed him.
-Rigsby and Sarah have a baby boy they name Benjamin.