The U.S. Supreme Court refused to shield a mystery company from having to provide information in what’s believed to be the criminal investigation being conducted by Special Counsel Robert Mueller.

Acting on a sealed request from the company and making no comment, the justices declined to block a federal appeals court ruling that apparently favored Mueller. The appeals court upheld daily fines against the company, owned by an unidentified foreign country, for failing to comply with a grand jury subpoena.

The latest order lifts the hold Chief Justice John Roberts had placed on the appeals court ruling while the Supreme Court considered the matter. There were no published dissents.

Mueller is investigating Russian interference in the 2016 presidential election and possible obstruction by President Donald Trump. The case apparently marked the first time the Supreme Court has been asked to intervene in the investigation.

The grand jury dispute has been shrouded in mystery, in part because officials closed an entire floor of a federal courthouse in Washington during arguments on Dec. 7. Politico linked the case to Mueller in October, citing a conversation overheard by a reporter in the court clerk’s office.

The appeals court order rejected contentions that a federal sovereign-immunity law shielded the company from having to comply. The Supreme Court order offered no elaboration.

The Supreme Court’s online docket includes the number of the appeals court case but doesn’t say who submitted the application. The case is In Re Grand Jury Subpoena, 18A669.