I’m fairly sure this was an episode of a regular TV mystery show, though it might have been something like ‘Colombo’ where there were just a few movie length episodes a year vs. a weekly series. I think I saw it within the last few years… but I do watch a lot of older shows on Netflix and independent stations and so on.
The ultimate solution to the mystery is that one twin (male, adult but youngish) has killed his twin and taken over his life. The mere existence of the killer twin was always kept as a secret: the two were used in a magic act with their father (uncle?) with illusions that depended on there secretly being two of them.
Somehow the ‘public’ twin had become rich, and the ‘secret’ twin was still unknown, resentful, and basically driven nuts by the way he’d had to live from childhood on. I think there was some random selection for which of them had to be hidden and which got to live a normal life.
There was an episode of Columbo with twins, played by Martin Landau, but one didn’t kill the other - they both conspired to kill their rich uncle. One was a celebrity chef, and there was a very odd scene where Columbo joins him on stage to make hollandaise sauce.
However, there was an episode of Endeavour where a demanding uncle used his nephew in his Circus / Magic act as a child, and the plot revealed that as adults one of the other characters (the murderer) in the episode was a twin from the old magic act. Could that be it?
There was an ep of “CSI” called “The Evil Twin” that sounds somewhat similar to what you’re describing.
Edit: Scratch that: That was CIS: Cyber. I’m remembering a different ep from the original CSI.
We have a winner! I found an extensive synopsis of this, and it’s definitely what I was, it turns out, (mis)remembering.
I remember now: I visited my sister last January for a few days, and Endeavor was one of her favorite shows, so I ended up semi-watching it. Don’t know why the vague memory popped up over the past weeks but it’s been haunting me – so I thank you for putting it to rest.
There was an episode of Hill Street Blues where something like this happened, but the brothers weren’t twins. They were, however, only a year or two different in age. The younger was able to beat the rap because he was “juvey.”
A similar-ish tale was used in an episode of SVU with T.R. Knight. Twins. DNA confusion. One twin masquerading as the other. But both alive at the end.
Probably the CSI: “Split Decisions” episode, but I think similar material was covered in CSI: Miami.
There were two older twins and a younger identical sibling (IVF, split zygote and frozen embryo). Epigenetic analysis could be used to distinguish between the two older siblings, allowing specific DNA (and actions) to be attributed, but it was the younger sibling that was the prime motivator.
I also thought of the Endeavour episode from the OP.
Although it has nothing to do with the question, one twin pretending to be another on a mystery show immediately made me think of a Magnum P. I. episode “Echoes of the Mind.” Sharon Stone played the twins, but one had died years before and the other went mad and had a kind of multiple personality disorder.
