We won't until the Serbs themselves are willing to come clean upon the subject, but, alas, there's little hope for that coming to pass.
Point being, there was an effort to transport corpses out of Kosovo and hide them in Serbia proper, much like the effort to hide the evidence of the Srebrenica mass executions.
Serbia's about the only European country where the government can transport hundreds of corpses to police grounds, burn and bury them, and the responsible agencies can carry on "business as usual" after the corpses have been recovered. (800+)
No worries, however - if the Serbs are unwilling to deal with the criminals in their midst, there are other ways of addressing the issue, mainly isolating the Serbs and ensuring they don't exercise any power over those they have recently victimized.
Which is why Kosovo will be granted independence this year - we're just tired of the Serb's BS.
And if some still think, after 6 years of Republican leadership, that Bill Clinton is the deus ex machina of American Balkan policy, well, some folks you just can't reach, and after a while it becomes a waste of time to even try.
You can’t have your cake and eat it too.