Semyon Markovich Semenov, (1911–1986): graduated from the Moscow Textile Institute in 1936 with a specialty in power engineering.
Semenov joined the KGB in 1937 and was immediately sent to the United States as an intelligence officer. Enrolled at the Massachusetts Institute of Technology, from which he graduated in June 1940 and shortly thereafter began working for Amtorg. Semenov had a mastery of French and English.
Semenonv worked first as a purchasing agent for the Soviet agency Machinoimport and then as head of the engineering department of the Soviet Purchasing Commission during World War II, with offices both at the commission and at Amtorg while specializing in scientific and technical espionage.
A Russian Foreign Intelligence Service history quotes his KGB personnel files as stating, “While working from 1938 through 1944 in the United States, Major Semenov showed himself to be one of the most active workers in the rezidentura [station] and credits him with connecting to 20 agents along the scientific and technical line."
In 1942 Semenov persuaded Vasily Zarubin to transfer Julius Rosenberg and his contacts from the CPUSA-Jacob Golos channel to the direct control of the Rezidentura, with himself as the assigned case officer. The actual turnover occurred on Labor Day weekend, 7 September 1942, at a meeting in Central Park. Bernard Schuster brought Rosenberg to the meeting. Rosenberg was then subjected to a thorough vetting and recruitment process to include training in tradecraft and a probationary period. Alexander Feklisov was assigned to assist in handling Rosenberg. Once the formal recruitment of Rosenberg was completed, Semenov used Rosenberg to conduct formal recruitments of two of Rosenberg's friends from City College of New York, Joel Barr and William Perl.
Semenov drew to collaboration a large group of young scientists and specialists, through whom was obtained a significant quantity of valuable materials on "ENORMOZ" (Manhattan Project), radio electronics, jet aviation, chemistry, medicine. Semyonov received from Bruno Pontecorvo in January 1943 a full report on the first nuclear chain reaction. Pontecorvo also relayed to Semenov in early in 1943 that "Fermi was prepared to provide information".
"Mr. Hoover" letter
In 1943 Semyon was denounced in the "Mr. Hoover" letter written by Vassili Mironov, an assistant to Zarubin. Mironov wrote anonymously of Semenov, "SEMENOV works in AMTORG, is robbing the whole of the war industry in America. SEMENOV has his agents in all the industrial towns of the U.S.A., in all aviation and chemical war factories and in big industries. He works very brazenly and roughly, it would be very easy to follow him up and catch him red handed. He would just be glad to be arrested as he has long been seeking a reason to remain in the U.S.A., hates the NKVD but is a frightful coward and loves money. He will give all his agents away with pleasure if he is promised an American passport." 
Semenov was recalled to the Soviet Union because of stepped FBI counterintelligence afterward. Later Semenov undertook assignments in France and in Moscow and rose to the rank of lieutenant-colonel.
In 1950 in connection with the Doctors' plot, the foreign intelligence began removing persons of Jewish nationality. In spite of significant positive results in his record, Semenov was discharged. He worked as translator in the publishing house Progress. Semenov was rehabilitated in the 1970s.
For the fulfillment of special targets on the line of scientific and technical intelligence, including on the atomic programs, Semenov was awarded the Order of the Red Star and awarded the Order of the Red Banner of Labour.
- Anonymous letter to Hoover, undated (received 7 August 1943), National Security Agency Venona Collection, English translation pg. 1.
- Russian Foreign Intelligence Service (SVR) 
- John Earl Haynes and Harvey Klehr, Venona: Decoding Soviet Espionage in America (New Haven: Yale University Press, 1999).