Jeff Hull, owner of Hull Funeral Service in Connecticut, says Magruder died on May 11 of complications from a stroke.
Magruder was Nixon's deputy campaign director and then served in the Republican president's administration.
He spent seven months in prison for lying about the involvement of Nixon's re-election committee in the 1972 break-in at Washington's Watergate complex.
The burglary eventually led to Nixon's resignation. Magruder later became a minister.