If this is evidence of Natalee's fate and if there are fingerprints on the duct tape, then hopefully they belong to the perp, whoever that may be.
Did you see this, written by Dan Riehl? Not that it would change what has transpired, but it shows that every "eye-witness" has a different concept of what happened initially.
http://www.bloggernews.net/showstory.asp?page=blognews/stories/WN0000309.txt