Highly recommend "Paradise Lost: The Child Murders at Robin Hood Hills", and the follow up "Paradise Lost: Revelations". They are docs from the 1990's that are very compelling. And I bet that the opinion you have after watching the first one, will completely change after watching the 2nd one.

Here's the trailer from the first one.







I also just watch "Burma VJ: Reporting From A Closed Country", and it was excellent. Here's the trailer.