Federal prosecutors using a second grand jury in Florida as part of Trump classified documents probe

A grand jury based in southern Florida has heard testimony from multiple witnesses in recent weeks as part of the federal investigation into former President Donald Trump's handling of classified documents, sources told CNN.

Another witness is expected to appear Wednesday at the federal courthouse in Miami as the investigation continues to develop, and the grand jury is expected to hear from at least one additional witness after that.

It remains unclear why the special counsel is using a grand jury in southern Florida after months of relying on grand juries in Washington, DC, to help gather evidence and witness testimony in the classified documents case. Sources close to Trump told CNN they are unaware of the reasoning for the Florida grand jury.

Special counsel Jack Smith's investigation into potential mishandling of classified materials and possible obstruction appears to be nearing its final stages.

Smith has authority to operate and bring charges in any federal court jurisdiction. He has yet to bring any charges, and Trump has denied any wrongdoing.

In the early stages of the investigation, a search warrant for Trump's Mar-a-Lago resort was approved by a court in south Florida. Since then, the Washington grand jury has been gathering evidence in the documents probe but hasn't met since early May.

Notably, an assistant US attorney from the Miami office was present last August when the search warrant for classified material was executed at Mar-a-Lago, a source familiar with the event told CNN.

Questions about the venue for the classified documents investigation were raised before Smith's appointment last November, as the probe involves the handling of documents brought from the White House to Trump's resort in Florida.

Elie Honig, a senior CNN legal analyst and former federal prosecutor, said there are benefits and drawbacks to bringing a case in either Florida or Washington, DC.

The difficulty for Smith, Honig said, is that Florida would be a more obvious place to file charges based on the actions at Mar-a-Lago, but Washington may give prosecutors a more favorable jury pool at trial to win a conviction if charges are brought.

"Federal prosecutors have broad discretion on where to file charges," Honig said. "Usually, so long as some portion of the charged conduct happened in a given district, the case can be charged there initially - though the defendant can seek to change venue after charges are filed."

This story has been updated with additional information.