Mr. Ornato, a former Secret Service agent and White House aide, is at the center of a dispute over competing accounts of President Donald J. Trump’s actions.
The Homeland Security Department’s inspector general told the Secret Service to halt its internal investigation into how phone records from around Jan. 6 were purged.
Mr. Ornato, who was Donald Trump’s deputy chief of staff for operations, has become a key figure in a dispute over testimony from the Jan. 6 committee’s star witness.