Many emigrants left their native country without permission from their government. While illegal emigrants did not receive permission to emigrate, governments sometimes tried to identify them after their departure. One example of an index of illegal Swiss emigrants is Faust, Albert Bernhardt. Lists of Swiss Emigrants in the Eighteenth Century to the American Colonie s. 2 vols. National Genealogical Society, 1976.
Some professional researchers have lists of illegal emigrants in their files.
For information on hiring a researcher, see the Family History Library's Hiring a Professional Genealogist . Other Published Lists and Indexes. More than 2,600 other published sources are listed in Filby, P. William. Passenger and Immigration Lists Bibliography, 1538-1900 . About half of the above lists are indexed in Filby, P. William.