Phnom Penh, Cambodia ? Ta Mok, known as “The Butcher” for his brutality as military chief of the communist Khmer Rouge, died today, his lawyer said. He was believed to be 80.

Ta Mok had been in and out of consciousness since last week at the military hospital in the capital, Phnom Penh, where he was being treated for high blood pressure, tuberculosis and respiratory complications, attorney Benson Samay said. Ta Mok had been in government custody since 1999.

Ta Mok, who briefly led the Khmer Rouge during its final days, was one of two former senior officials of the movement in detention awaiting trial on charges of crimes against humanity committed during a 1975-1979 reign of terror, when an estimated 1.7 million Cambodians died of starvation, overwork, diseases and execution.