Demetrius Dvoichenko-Markov, was an American citizen and spy for the New York KGB Rezidentura from 1943 to 1945. His mother, Eufrosina Dvoichenko-Markov, also served Soviet intelligence during World War II. Dvoichenko-Markov was a sergeant United States Army who sent materials to the Soviet intelligence while assigned to military counterintelligence in Alaska.
Demetrius Dvoichenko-Markov codename in Soviet intelligence is "Hook". Dvoichenko-Markov is referenced in the following Venona project decryptions:
- 894 KGB New York to Moscow, 10 June 1943
- 627 KGB New York to Moscow, 5 May 1944
- 864 KGB New York to Moscow, 16 June 1944
- 1053 KGB New York to Moscow, 5 July 1945
- John Earl Haynes and Harvey Klehr, Venona: Decoding Soviet Espionage in America, Yale University Press (1999), pg. 259, 347, 449.