They are seeking a 30-year jail sentence.
Van der Sloot was widely known before the May 30, 2010 killing of 21-year-old Stephany Flores as the prime suspect in the unresolved 2005 disappearance in Aruba of the American teenager Natalee Holloway.
A lawyer for Flores' family, Edward Alvarez, told The Associated Press he was notified on Thursday that formal charges were filed.
He estimated the trial would begin in October.
Prosecutors are also seeking damages of more than $70,000.
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