Attorneys for former Goldman Sachs banker Roger Ng said they are considering moving for a mistrial after prosecutors revealed late Tuesday that a U.S. Department of Justice privilege review team failed to release thousands of documents related to the case, which involves a massive scheme centered on a Malaysian economic development fund.

Approximately 15,500 of the undisclosed documents are related to Ng’s former boss Tim Leissner, who pleaded guilty to several charges in 2018 and began testifying against Ng last week as the government’s star witness.