I am really good at the board game Clue and Larry King banging Miss Scarlet with his lead pipe in the conservatory doesn’t make any sense. This whole thing can go away quickly with one check of the medical records. His wife knows often the two of them were having sex (probably never since he looks like Larry King only naked). His doctor knows how often he was prescribing boner medicine. So check the medicine cabinet and do a little simple math.
The only thing he may have cheated with her sister on is cards