Wikipedia
SAVAK ( Persian: ساواک, short for سازمان اطلاعات و امنیت کشور Sāzemān-e Ettelā'āt va Amniyat-e Keshvar, Organization of Intelligence and National Security) was the secret police, domestic security and intelligence service established by Iran's Mohammad Reza Shah with the help of the United States' Central Intelligence Agency (the CIA) and Israeli Mossad. SAVAK operated from 1957 to 1979, when the prime minister Shapour Bakhtiar ordered its dissolution during the outbreak of Iranian Revolution. SAVAK has been described as Iran's "most hated and feared institution" prior to the revolution of 1979 because of its practice of torturing and executing opponents of the Pahlavi regime. At its peak, the organization had as many as 60,000 agents serving in its ranks according to one source, although Gholam Reza Afkhami estimates SAVAK staffing at between 4,000 and 6,000.