The General Accounting Office, the investigative arm of Congress, did a search of Government records in 1995 in order to determine if the "Government" at any level, was part of a coverup of the Roswell incident. GAO investigators with the highest levels of security and intelligence clearances accessed and reviewed archived documents, met with military and intelligence historians and queried the National Security Council, the White House Office of
Science and Technology Policy, the Department of Energy, the FBI, DOD, and the CIA.
Here is a link to the final 1995 GAO report
http://www.gao.gov/assets/230/221509.pdf