The Benghazi investigation has been the longest in special congressional investigative history:

The House committee investigating the Benghazi attacks is now the longest congressional investigation in history, committee Democrats announced today. As of Monday, the House Select Committee on Benghazi, has been active for 72 weeks — surpassing the record previously held by the Watergate Committee in the 1970’s.

Of course, the House committee investigation is one of seven separate congressional committees investigating the matter.  And NOT ONE has found intentional misconduct.  This top-shelf effort is spending a fortune in hopes of inventing something to destroy Hillary Clinton’s candidacy. The closest they’ve come is to discover that the former Secretary of State used an unconventional private email server that she shouldn’t have used.