The Justice Ministry said today that two discs containing documents were reported missing January 8 "having been dispatched by post." It said "intensive searches" had failed to find them.
The ministry says lawyers are reviewing the documents to determine whether they contain sensitive material.
Some of the documents relate to inquiries into the fatal police shootings of Azelle Rodney in 2005 and Mark Duggan in 2011. Duggan's death sparked several nights of rioting.
The third inquiry is looking at the 1997 death of a Northern Ireland man, Robert Hamill.