A former employee of Donald Trump has told federal agents the former president asked for boxes of records to be moved within his Florida residence after receiving a government subpoena demanding their return, the Washington Post reported on Wednesday.

The testimony of the key witness, coupled with surveillance footage the Justice Department also obtained, represent some of the strongest evidence to date of possible obstruction of justice by Trump. The FBI conducted a court-approved search on Aug. 8 at Trump’s home at the Mar-a-Lago estate in Palm Beach, seizing more than 11,000 documents including about 100 marked as classified.