I know the one you're referring to, that's a separate documentary from the late 90's/early 2000's I think. It's what brought the case some more attention and made people question whether the three imprisoned were innocent.I'm not sure if it's the same documentary, but there's a 3 part documentary called Paradise Lost that was made at the time the guys were tried. I watched it on Youtube after I'd heard about the case. Gripping stuff and definitely recommend it. Warning through -first few mins of it shows the dead boys' bodies so not for the faint hearted
They also show the dead bodies in West of Memphis and agree it is very hard viewing!