The special counsel has questioned witnesses about a so-called "hidden room" inside Mar-a-Lago that wasn't searched by the FBI during their August 2022 raid, sources say.

The FBI missed the rooms in their search for classified documents, said sources.

Special counsel Jack Smith’s team has questioned several witnesses about a closet and a so-called “hidden room” inside former President Donald Trump’s residence at Mar-a-Lago that the FBI didn’t check while searching the estate in August 2022, sources familiar with the matter told ABC News.

As described to ABC News, the line of questioning in several interviews ahead of Trump’s indictment last year on classified document charges suggests that – long after the FBI seized dozens of boxes and more than 100 documents marked classified from Trump’s Mar-a-Lago estate – Smith’s team was trying to determine if there might still be more classified documents there.

According to sources, some investigators involved in the case came to later believe that the closet, which was locked on the day of the search, should have been opened and checked.

As investigators would later learn, Trump allegedly had the closet’s lock changed while his attorney was in Mar-a-Lago’s basement, searching for classified documents in a storage room that he was told would have all such documents. Trump’s alleged efforts to conceal classified documents from both the FBI and his own attorney are a key part of Smith’s indictment against Trump in Florida.