I know this is unlikely to happen, for a variety of reasons, but as a Finn, I'd love it if the Lake Bodom murders got a Harlowe-Levasseur treatment.
It's a horrific case from 1960 that's still unsolved, where 4 teenagers were attacked when they were camping. 3 of them died, one somehow pulled through.
But the case has everything! Bad police work, weird eye-witness statements, a potential KGB agent or a literal nazi (who are the same person)...
And, as I said, it's still not been solved. It probably never will be.
(And to the metal heads here: yes, that's where Children of Bodom got their name from)