A Delaware federal judge has allowed Crystallex International Corp. to begin seizing shares of Citgo Petroleum Corp., as the Canadian gold mining and exploration firm looks to collect a $1.2 billion judgment against the Venezuelan government.

U.S. Chief Judge Leonard P. Stark of the District of Delaware on Thursday ordered that the U.S. Marshals Service start the sale process after he earlier this month granted the Canadian company’s bid to prevent Venezuela from avoiding an arbitration award over lost mineral rights.