It doesn't seem that the authorities are doing much. They were so slow in getting started and who knows how much evidence is just plain gone because of that. If it weren't for the Holloways, this would disappear into a black hole somewhere, I agree.
I was fooling around and will now try to post an item I found. Be patient, I'm a newbie. And I know this is not a 'reputable' source - I post it for interest and to compare to what we'd discussed here.
http://www.nationalenquirer.com/crime/63316
If Natalee wasn't an attractive, blond teen... and her mom wasn't an intelligent, attractive woman... FOX and the rest of the MSM would have dropped this long ago.