NEW YORK (AP) — The parents of Otto Warmbier have filed a claim for a seized North Korean cargo ship in a bid to collect a multimillion-dollar judgment in the American college student’s death.

Attorneys for the Warmbiers said in a court filing Wednesday they have a right to the assets after North Korea failed to respond to their wrongful death claim.Advertisement

The Warmbiers say their son was tortured after being convicted of trying to steal a propaganda poster and imprisoned for months.

He died days after being returned to the U.S. in a vegetative state in 2017. A U.S. judge has ordered North Korea to pay more than $500 million in the Warmbiers’ wrongful death suit.

North Korea has denied mistreating Warmbier.

The U.S. seized the cargo ship in May because it was carrying coal in violation of U.N. sanctions.