The criminal investigation into former President Donald Trump’s handling of classified documents and obstruction of justice has taken a new turn with the revelation of a previously unknown grand jury in Florida.

According to sources familiar with the matter, federal prosecutors have subpoenaed multiple witnesses to testify before the grand jury at the US district court in Miami, where Trump’s Mar-a-Lago resort is located.

The witnesses include Taylor Budowich, a former Trump aide who is expected to be questioned by Jay Bratt, the justice department’s counterintelligence chief detailed to the special counsel Jack Smith, who is leading the investigation.

The involvement of Bratt could indicate that prosecutors are looking into possible Espionage Act violations by Trump, who allegedly showed off national security documents to guests at his resort.

The Florida grand jury is separate from the one that had been taking evidence in Washington for months, but has been silent since May. It is unclear why prosecutors decided to impanel a new grand jury in Florida, and whether it is now the only one active in the case.

One possible reason is that prosecutors have developed evidence of criminal activity at Mar-a-Lago, which is in the southern district of Florida.

The investigation was sparked by an incident in October 2021, when an employee at Mar-a-Lago drained the resort’s swimming pool and flooded a room where computer servers containing surveillance video logs were kept.

While it is not clear if the flood was intentional or accidental, prosecutors have found it suspicious and have obtained surveillance footage to track how White House records were moved around the resort.

Prosecutors have also been examining any effort to obstruct their investigation after Trump received a subpoena in May 2022 for classified documents that he had retained after leaving office.

Trump’s lawyers have been trying to stave off an indictment by arguing that he had a right to keep the documents as part of his presidential records.