How to tell...

[telophase]

... whodunnit on Diagnosis Unknown, on Discovery Health as I type this: it's almost always someone poisoning someone else, and the poisoner is the person who was not interviewed for the show. It's incredibly obvious once you know what to look for, like figuring out if the person the cops have nabbed on [insert cop show name here] is the person whodunnit based on how far into the episode it is: if it's 20 minutes in, it's a wrongful arrest. At 50 minutes in, it's the true perp.

Comments

[wyrdness.livejournal.com]

That's similar to how I used to work out the Murder She Wrote plots. It always seemed to be the first person, who was nearly always doing something dodgy, the show would then try and make you believe it wasn't them right up until the end where they inevitably confessed. Unless they were a friend or somehow related to Jessica Fletcher, then they were always wrongfully accused and had a big hug at the end when the truth came out.