If you haven't seen Villisca: Living with a Mystery yet, you need to rent it or buy it and see it. It is a superb documentry by Kelly and Tammy Rundle. I was able to rent it through Netflicks but if you live in Iowa and some of it's surrounding states, you may be able to rent it at the local video store.
Once you've seen it you should consider voting for it as The Best True Crime Documentary for the Capote Awards. Vote for it here.
Kelly Rundle has no shame in promoting it and I don't blame him. It is an excellent film.