Trump attorney to testify Friday in Mar-a-Lago classified documents ...

Former President Donald Trump’s defense attorney Evan Corcoran is scheduled to testify Friday before the grand jury investigating classified documents found at Mar-a-Lago after a new order from a federal appeals court, a source familiar with the matter told CNN.

The US DC Circuit Court of Appeals said that Corcoran must provide additional testimony and turn over documents about the former president as part of the criminal investigation into possible mishandling of classified documents.

The source said Trump’s side is unlikely to appeal to the Supreme Court.

In response to the decision, a Trump spokesperson said, in part, that “there is no factual or legal basis or substance to any case against President Trump” and that “prosecutors only attack lawyers when they have no case whatsoever.”

The announcement from a panel of three judges in the appellate court – less than a day after Trump sought to put Corcoran’s testimony on hold – adds momentum to the special counsel investigation as it seeks to secure evidence that could make or break a federal criminal case against Trump.

The Justice Department has successfully argued in court that prosecutors have enough evidence that Trump’s interactions with the lawyer were part of a possible crime that they can pierce the confidentiality of the conversations between the two.

The documents at issue in the case are Corcoran’s handwritten notes and transcribed verbal notes, regarding his representation of Trump in the Mar-a-Lago probe, according to a source familiar with the matter.

Corcoran previously testified and declined to answer some questions, citing attorney-client privilege. Prosecutors are also seeking access to notes from Corcoran.

It’s not fully known what Corcoran’s testimony and documents would reveal.

This story has been updated with additional developments.

CNN’s Sara Murray contributed to this report.