…that is, the proper pronunciation of Van der Sloot (and did I get the capitalization right)?
I’ve heard all three, and it’s driving me nuts.
In the Netherlands it would probably more or less rhyme with “boat,” a long O sound which would be extended for a tad. Regional variations might allow for something close to a rhymes-with-flute sound, like in west Flanders or something. If the person is American, though, who knows.