Do you think murder mystery thrillers work better if the killer is known to the hero/a known character?

Spoilers for a variety of movies ahead, so if you aren’t well versed in murder mystery movies but are interested in them it might be better to not read.

Do you think a murder mystery movie is better off when the killer is a complete stranger or someone we are introduced to as a main cast member?

For me, I find when Hollywood tries to do the “it was this good guy along” cliche it’s almost always just so forced and weird.

I love Along Came A Spider, and I can even see the idea of the killer being a cop something that could make sense. But making the killer the very detective who works alongside Cross always felt a little… just ok? I mean it makes for a decent reveal I guess, but also feels so forced considering how crucial he was to the investigation.

In Se7en we have the complete opposite — the villain’s actor gets no billing in the marketing or opening credits and we don’t see his face until near the end.

I think in comedy movies, having a killer be a main cast member does make sense — Clue, Club Dread, Murder Mystery, etc, where it feels more like you’re invited to play a game of Clue as the story progresses. But for darker and serious thrillers I find the “it was secondary protagonist all along” trope a little tiresome and predictable. I think more often than not it works so much better as a complete stranger to the protagonist, which is how it would go down 99% of the time in real life.