Natalee's family were the ones who found out about Joran and the Kalpoe brothers. They found out within a very few hours after landing on Aruba, and they called the police's attention to them. After that, the police totally botched everything. The Aruban police did not have the Joran-Kalpoe lead until Nat's family gave it to them. That says a whole lot for what the true situation has been down there.
Ok, so roughly 24 hours later, the police arrive at Sloots. (I'm guessing they went there first). Is this when the security guards were fingered?