08/26/2014 AT 02:45 PM EDT
Joran van der Sloot, the prime suspect in the 2005 disappearance of U.S. teen Natalee Holloway
, has been moved to a remote Peruvian penitentiary after authorities said he threatened to kill the warden of the prison where he was serving a 28-year term
Peruvian prison spokeswoman Janeth Sanchez told the Associated Press that the 27-year-old Dutchman was moved Sunday to Challapalca, located high in the Andes near the Bolivian border. He previously was held at a prison north of Lima.
Van der Sloot was the last person seen with Holloway, who vanished while on a graduation trip to Aruba. He is imprisoned for killing Stephany Flores
, a 21-year-old Peruvian business student, in 2010.
He married his pregnant Peruvian girlfriend
in a prison ceremony last month.