The first season of True Detective.
No official storyform, but I think the first season of The Sinner on Netflix.
And what about Knives Out? Isn't Benoit Blanc the Protagonist?
EDIT: I'm acutally not sure about The Sinner. I think that it might actually have two storyforms, one that's backstory and the other that's figuring out the mystery of what happened. But I still think the Protagonist for the investigation piece is the detective and the Jessica Biel character is the MC.