No spoilers, but "The Staircase" documentary series was one of the earliest (in their current iteration) compelling true-crime documentary series to air. I found it to be exceptionally good because so many of the protagonists agreed to take part and give interviews over the years.
It's interesting that this drama includes the making of that doc series as part of the narrative. The whole thing was commissioned by French broadcaster Canal+ (and shown in the UK by the BBC). The most recent episodes were co-commissioned by Netflix, where I notice the entire original series is now back trending.
It has been years since I saw that original series, and I don't think I ever watched the sequels, but at this point I'll stick with the drama before "spoiling" anything more than I already know.
Adam