Van der Sloot is charged with killing Stephany Flores in 2010 after leaving a casino.
The murder took place exactly five years after the disappearance of Natalee Holloway, who was seen leaving a nightclub in Aruba with Van der Sloot. Holloway's body has never been found.
Authorities said Van der Sloot, 24, confessed to killing Flores, claiming he became enraged after she discovered his connection to Holloway.
Van der Sloot's attorney wants the confession thrown out because the defense lawyer present when he made the confession was state-appointed and no official translator was there.
Defense attorney Jose Luis Jimenez told The Associated Press that there was a 70 percent chance Van der Sloot will plead guilty, which could help him get a reduced sentence.
Prosecutors are seeking a 30-year prison sentence for Van der Sloot on murder and theft charges. Lawyers for Flores' family will try to show that Van der Sloot killed her to steal money she won at the casino.
The two met at the Atlantic Casino in Lima. They were seen playing at the same table, and then leaving together.
Van der Sloot's attorney will argue that his client was in a state of emotional distress when he killed Flores and "seek to reduce the charge from first-degree murder to simple homicide."
Van der Sloot has been in custody after his arrest in Chile just days after Flores' death.
The Associated Press contributed to this report.
