Washington (CNN) The parents of Otto Warmbier filed a wrongful death lawsuit against the North Korean government on Thursday charging that the country's regime tortured and killed their son, according to lawyers for the family.

Warmbier -- the 22-year-old American student who was detained in North Korea for 17 months -- was returned to his family "with severe brain damage and in a nonresponsive state" in June 2017.

He died on June 19, 2017.

"Otto was taken hostage, kept as a prisoner for political purposes, used as a pawn and singled out for exceptionally harsh and brutal treatment by Kim Jong Un," Otto's father, Fred Warmbier, said in a statement.

"Kim and his regime have portrayed themselves as innocent, while they intentionally destroyed our son's life. This lawsuit is another step in holding North Korea accountable for its barbaric treatment of Otto and our family," the statement said.

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