William Perl, whose real name was William Mutterperl, was an American physicist and Soviet spy.
While a student at the City College of New York, Perl joined the Steinmetz Club, the campus branch of the Young Communist League, where he met and befriended Julius Rosenberg, Morton Sobell and Joel Barr. Perl graduated with a degree in engineering in 1939, and in 1940 began working for the National Advisory Committee for Aeronautics (NACA) at their Langley Army Air Base research facility in Hampton, Virginia. In 1944 Perl transferred to the NACA Lewis Flight Propulsion Laboratory in Cleveland, Ohio. Both jobs provided Perl with access to extensive classified materials. NACA sent Perl to Columbia University to pursue doctoral studies in Physics. While at Columbia, Perl lived in the same Morton Street apartment where Barr and Alfred Sarant had lived.
Following his doctoral work at Columbia, Perl returned to Cleveland to work on a jet propulsion project related to supersonic flight. Perl was nearly given a position with the U.S. Atomic Energy Commission when his connection with Barr and Sarant, suspected Communists, was turned up by a security check. In July 1950, Vivian Glassman, Barr's fiancée, visited Perl in Cleveland to give him $2,000, advising him to go to Europe. Unlike Barr and Sarant, Perl decided not to flee the country, perhaps thinking he might be able to salvage his career.
Perl appeared before the Rosenberg Grand Jury in the summer of 1950, denying any relationship with Julius Rosenberg, Morton Sobell, Max Elitcher, Ann Sidorovich, and Michael Sidorovich. The Federal Bureau of Investigation suspected Perl of providing information to the Soviet Union, and he was arrested on March 15, 1951. Evidence that Perl had engaged in espionage activities was mostly circumstantial, so the FBI was forced to settle for perjury charges. In May 1953 a jury found Perl guilty of two counts of perjury for lying about his relationship with Rosenberg and Sobell. He was acquitted of two other counts. Perl served two concurrent 5 year sentences at the New York House of Detention, maintaining his innocence in any espionage plot.
Perl is mentioned in 14 KGB messages decrypted by the VENONA project, a joint British-American intelligence effort, under the covernames 'Gnome' and 'Jacob'. One cable, dated 14 September 1944, requests a $500 bonus for Perl's information on a Westinghouse jet engine assembly. John Earl Haynes and Harvey Klehr have suggested that data provided by him aided the Soviets in the unique tail-fin design of the MiG-15 fighter used in the Korean War.
- Douglas Linder, A Trial Account (2001)
- John Earl Haynes and Harvey Klehr, Venona: Decoding Soviet Espionage in America, Yale University Press (1999), pg. 259, 347, 449. ISBN 0-300-07771-8.
- John Earl Haynes, "Cover Name, Cryptonym, CPUSA Party Name, Pseudonym, and Real Name Index. A Research Historian’s Working Reference" (revised February 2007), on the author's web site.
- Ronald Radosh and Joyce Milton, The Rosenberg File, New Haven: Yale University Press, 1997. ISBN 0-300-07205-8
- Katherine A. S. Sibley, Red Spies in America: Stolen Secrets and the Dawn of the Cold War, Wichita: University Press of Kansas, 2007. ISBN 0-700-61555-5