The Justice Department on Friday is set to make public a redacted affidavit detailing evidence that led to the FBI search of former President Donald Trump’s Mar-a-Lago home, where agents seized more than two dozen boxes, some containing classified documents and other highly sensitive information.

The affidavit, due to be filed in federal court in Florida by noon, is expected to offer new glimpses into the Justice Department’s investigation into Mr. Trump’s handling of classified material and presidential records as well as the government’s justification for the Aug. 8 search.