Here is a bit more on this search for your father's records. Immigration and Citizenship Enforcement - http://www.ice.gov/about/index.htm - refers FOIA requests:

NOTE: All requests for Alien Files, including all records therein, should be requested from U. S. Citizenship and Immigration Services, The National Records Center, FOIA Division, P.O. Box 648010, Lee's Summit, MO 64064-5570. Alien Files are under the control of U.S. Citizenship and Immigration Services. Please refer any questions about Alien File record requests to Director, Freedom of Information/Privacy Act Program at (202) 272-8269.

There is much more information on the FOIA page - http://www.ice.gov/about/index.htm - regarding the many regulations involving these requests, including the statement: "The Privacy Act (PA), 5 U.S.C. § 552a provides lawful permanent residents and U.S. citizens a right of access to records filed in an agency system of records, which are retrieved by their name or personal identifier." This would appear to mean that only US citizens or permanent residents can make these requests.

The Lee’s Summit National Records Center page - http://www.archives.gov/central-plains/lees-summit - makes it fairly clear that you can’t deal directly with them. It appears to be a high-security facility that deals ONLY with government personnel.

Records of the Immigration and Naturalization Service [INS] (Record Group 85) 1787-1993 (bulk 1882-1957) http://www.archives.gov/central-plains/lees-summit mentions lists of deportations from Northeastern U.S. ports, but ONLY up to 1951. 85.5.3 Records of INS District No. 4 (Philadelphia, PA) includes: "Departure reports of aliens, 1942-51."

I also dug into Dissertations using the very broad search: deportation*, and got a few that seem to vaguely relate to the 1950s time period. "Cedric Belfrage: Anglo-American nonconformist." (Volumes I and II) by Palmer, Jennifer Susan, Ph.D., University of Delaware, 1993, 588 pages; Proquest No. AAT 9419567 mentions Belfrage's "...voluntary deportation to Great Britain in 1955." In the list of references at the end it says: "The FBI provided Cedric Belfrage’s records from their files. Their records were under 100-34463 and 65-56402." FBI FOIA pages are at: http://foia.fbi.gov/foiaindex/foiaindex_d.htm including many "often requested" pages. The search: deportation* in http://foia.fbi.gov/search.htm gets only 5 hits, however. I would think the ICE FOIA request mentioned above would be the best place to start. I think an FBI FOIA request is likely to be more difficult, and would not seem to be your logical first step if in fact the old deportation records still exist.