Thank you to this Website for recommending two very good murder mysteries- Diary of a Madman, and this episode Killer Instinct! It is amazing that we have such beautifully designed and organized Web access to this treasure trove of CBS Radio Mystery Theater from our childhoods that has no equal today. I always like to recommend another episode when commenting, so I would say Cabinet of the Unsolved is a good mystery too - with two added bonuses: a train and a heart.