Erich Mielke, who has died in Berlin aged 92, was feared and hated more than any other man in communist East Germany. As minister for state security from 1957 until the regime's collapse in November 1989, he commanded a network of 92,000 professional spies and 170,000 voluntary informers and part-time snoops.
Mielke's agents kept such a close watch on East Germany's 16m citizens that organised political opposition was almost impossible. Those identified as critics of the system could face imprisonment and torture, including fatal exposure to radiation. Although he spent five years in prison after German re-unification, he was never called to account for these crimes - or for the murder of hundreds of easterners who tried to escape to the west.
Pedantic, bureaucratic and humourless, Mielke was viewed by many as an unprincipled, heartless party functionary, whose actions were motivated by nothing nobler than a desire to keep himself and his cronies in power. In fact, he was a life-long communist, whose political biography was shaped by his experience in the early decades of the last century.
Born in the working-class Berlin district of Wedding, Mielke had a tough childhood, made grimmer by the early death of his mother. Like many of his neighbours in "red Wedding", his father favoured the communist KPD over the more moderate Social Democrats, and Mielke himself joined a communist youth group at the age of 12.
As a gifted schoolboy, he won a state scholarship to one of Berlin's most prestigious schools but dropped out after only two years when his teachers told him that the educational deficit caused by his underprivileged background could not be overcome. The experience further radicalised the young communist and, when the KPD set up a paramilitary group for "party self-defence", he was among the first to join. Much of the group's time was spent playing a harmless cat-and-mouse game with the police, but it became deadly earnest for Mielke on August 9 1931, when he shot dead a policeman during a demonstration in the centre of Berlin. Aged only 23, he escaped to Belgium using identity papers supplied by the Soviets and, nine years later, went to the Soviet Union.
Trained as a professional revolutionary at the Lenin school, Mielke returned to Germany after the second world war and, with other German communists who had spent the war years in Moscow, helped to establish the German Democratic Republic.
Politically unsophisticated, with a mindset frozen in the prewar years - when communists saw Social Democrats as their worst enemies - Mielke was nonetheless a brilliant secret policeman. From the moment he took charge of the Stasi in 1957, the agency out-performed most of its western rivals.
East Berlin planted an agent in the office of West German chancellor Willy Brandt and, as the German public has discovered in re cent months, its agents knew more about Helmut Kohl's financial misdemeanours than most of the former chancellor's closest aides. When Mielke celebrated his 80th birthday in 1987, the Communist party newspaper was still describing him as a national hero.
Less than two years later, his entire world had collapsed. Five days before the fall of the Berlin Wall, as a million East Germans demonstrated against the government on Alexanderplatz, Mielke ordered his men to put aside weapons to defend themselves and their families. On November 13 1989, as easterners streamed westwards through the newly-opened border, he attempted to justify himself with the words "But I love everybody".
Mielke spent five months in prison on remand after he was charged in connection with the wall shootings, but his trial was postponed so he could be charged with the 1931 murder. He served four years of a six-year sentence for that crime, but was later judged too senile to face trial for his actions as a leader of the East German regime.
After his release in 1998, he moved into a flat in a high-rise building in an eastern Berlin suburb with his wife, Gertrude, where he remained until his move last month to the nursing home where he died. Although Mielke never explained or excused his actions on behalf of the regime, he admitted in 1993 that he felt his life had been wasted.
"Millions have died for nothing," he said. "Everything we fought for - it has all amounted to nothing."
James Fitzmaurice
Erich Mielke, secret policeman, born December 28 1907; died May 22 2000