I was in the mood for some mystery & misery but couldn't find anything that didn't look completely stupid so I figured a documentary could do the trick.

Considering how and where the murdered British couple lived at that time - kinda like a recipe for disaster - it is peculiar that the tragedy unfolded in this particular way.
Even though I hate to compare human sufferings, I think the #1 worst nightmare is when a loved one goes missing and never gets found. It's such an impossible kind of grief.
That's not what happens in this documentary but it does show how important closure can be even if it's just a symbolic one.
I don't think that confronting a sociopath with his/her misbehaviour will result in satisfaction or justice, but at least there's the public acknowledgment of what happened and by whom.
It's all very nasty and I got more misery than I had bargained for.
Btw, should you ever stumble upon a documentary about Marc Dutroux, think
hard before you click on it.
I watched one on youtube (possibly made for television because it didn't look as slick as the streaming documentaries) and I was seriously disgusted and depressed for more than a week. Not that I didn't know what it was all about but I really wish I hadn't watched that video about unfathomable horrors.