A native of Berlin and a second-generation member of the Communist Party of Germany, Mielke was one of two triggermen in the 1931 murders of Berlin Police captains Paul Anlauf and Franz Lenck. After learning that a witness had survived, Mielke escaped arrest by fleeing to the Soviet Union, where the NKVD recruited him. He was one of the key figures in the decimation of Moscow's German Communists during the Great Purge as well as in the savage persecution of suspected anti-Stalinists in the International Brigade during the Spanish Civil War.