The special counsel's office is continuing to investigate around Donald Trump's handling of documents after his presidency ended, multiple sources tell CNN.

That includes continued grand jury activity in Florida and inquiries of witnesses, though it is not yet clear what aspects of the investigation the prosecutors are still pushing toward.

The historic indictment last month of Trump and his aide Walt Nauta already tells a thorough story with photos, text messages and witness accounts about how Trump allegedly held onto national defense records after his presidency.

Prosecutors also accuse both men of lying to investigators and trying to conceal the records from being repossessed by the federal government by moving them throughout his Mar-a-Lago club.

Trump has pleaded not guilty, and Nauta is expected to enter a plea of not guilty next week. The two men are expected to head to trial as early as this year.

It's not unheard of for investigators working a case to continue asking questions following the filing of initial charges, though the Trump case is unusual given the former president continues to run for the Republican nomination for president in 2024.

And the documents case on file against Trump and Nauta left out several threads investigators pursued as recently as May, including questions about possible gaps in surveillance tapes and the handling of records at Trump's Bedminster golf club in New Jersey in 2022.

A spokesman for the special counsel's office declined to comment on Thursday.

This story has been updated with additional details