Mam Nai or Mam Nay, nom de guerre Comrade Chan is a war criminal and former lieutenant of Santebal, the internal security branch of the Khmer Rouge communist movement, which ruled Democratic Kampuchea from 1975 to 1979. He was the leader of the interrogation unit at Tuol Sleng (S-21), assisting Kang Kek Iew (Comrade Duch), the head of the camp where thousands were held for interrogation, torture and subsequent killing.