WASHINGTON (AP) — The Latest on President Donald Trump and the House impeachment investigation (all times local):

10:30 a.m.

House Intelligence Committee Chairman Adam Schiff says President Donald Trump’s administration is “building a powerful case” for impeachment as a former White House national security adviser defied a subpoena on Monday.

Charles Kupperman failed to show up for a scheduled deposition Monday after asking a federal court in Washington for guidance on whether he was legally required to do so.

Schiff, who is leading the impeachment probe, says Kupperman’s suit has “no basis in law” and speculated that the White House didn’t want him to testify because his testimony could be incriminating. Democrats are investigating Trump’s overtures to the Ukrainian government to pursue politically motivated investigations.

Schiff says the three committees leading the inquiry will “move forward” even if witnesses don’t appear.

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10:25 a.m.

The Justice Department is appealing a judge’s order directing the department to produce to the House secret grand jury testimony from special counsel Robert Mueller’s Russia investigation.

The department also asked Monday that the judge’s order be put on hold until a federal appeals court has an opportunity to weigh in.

Chief U.S. District Judge Beryl Howell on Friday directed the Justice Department to produce by October 30 grand jury testimony referenced in Mueller’s report. That information could be of value to House lawmakers conducting an impeachment inquiry of President Donald Trump.

The department says that once the grand jury material is released to the House Judiciary Committee, there is no guarantee that it will remain secret.

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8:00 a.m.

A former deputy national security adviser expected to testify in the House impeachment inquiry is signaling that he won’t appear Monday as scheduled.

Charles Kupperman was supposed to testify behind closed doors, but last week asked the federal court in Washington for guidance on whether he was legally required to do so.

The court had yet to rule by Monday morning. At issue is whether the subpoena from Congress takes precedent over the White House’s position that Kupperman is immune from having to testify as a close adviser to the president.

In a letter Sunday obtained by The Associated Press, Kupperman’s attorney wrote that if a judge sides with Congress, Kupperman will comply with the court order.