[2][3][4][5] Bruno Sattler was born at Schmargendorf, a rapidly expanding municipality on the south-western edge of Berlin, into which it has subsequently been subsumed.

[7] He also found time to join the Ehrhardt Brigade, one of the "Freikorps" units of defeated former imperial army soldiers that emerged during the months of revolution which broke out after the war.

Bruno Sattler had imbibed to the full his parents' "traditional values", which in his case involved not just the rather nostalgic nationalism that was widespread among those hankering for "the good old days, before the war", but also a gnawing antisemitism.

According to a surviving Gestapo organisation chart dated 22 January 1934 he was at that time in charge of "Department III B2: SPD, SAP, Reichsbanner, Trades Unions and Special Projects".

One of these, recruited by Sattler in the summer of 1936, was Herbert Kriedemann who after the war served as a long-standing member of the West German Bundestag (parliament) (SPD) between 1949 and 1972.

[8][10] It was as an ambitious still relatively young Gestapo officer, on the night of 1/2 February 1934, that Sattler was responsible for the killing of four communist detainees, John Schehr, Eugen Schönhaar, Erich Steinfurth and Rudolf Schwarz at the "Schäferberg" (just outside Berlin), "while they were attempting to escape".

[12][13] Although Sattler was in charge of the group of Gestapo men escorting the prisoners when the incident took place, it was never known whether or not he fired any of the fatal shots.

Bruno Sattler immediately assumed leadership of the new organisation's "Department IV A2", with responsibilities covering Sabotage Prevention, Political-Police Defence and Political Counterfeiting operations.

As overall head of Department IV, during the summer of 1940 he was briefly posted to newly occupied Brussels, responsible for taking care of the files of the Second Socialist International which had been based in the Belgian capital between 1935 and 1940.

Between September 1941 and January 1942 Sattler was listed as an "orderly officer" of "Advance Command Moscow" of the Special Commando with "Taskforce Group B".

Complementary research that would not have been possible before 1990 has nevertheless endorsed assessments relating to his culpability, notwithstanding sometimes highly critical evaluations of the East German justice system.

Records of the 1952 trial state that following Sattler's installation as Belgrade's Gestapo chief, the population of Yugoslavia was subjected to merciless persecution and mass killings.

Through his adept recruitment and control of a network of informants Sattler received details of the structural organisation and activities of all the resistance groups in the region.

When it came to those held back as hostages, initially these were shot dead in the ratio of 100 for every German soldier believed killed by resistance partisans.

In October 1944 the Germans troops and administrators were ejected from Serbia by a potent - if slightly implausible - de facto alliance between Yugoslav Partisans and the Soviet army.

Mindful, at least in outline, of the inevitability of approaching Cold War, and through the mediation of his wife, he intended to make contact with the Americans and offer his services as a man with useful knowledge of how to track down and locate communists.

[20] But in the immediate term his overriding objective was to avoid capture: for a year and a half he lived hidden by a cousin, in the American zone.

[25] Early in 1947 he turned up in the by this time diminished mountain of rubble that had been Berlin[6] where he lay low in a boarding house in the Dettmannstrasse (today renamed as the Stauffenbergstrasse).

Someone had seen him being beaten to death in the "bunker" (formerly used as a vast air-raid shelter and subsequently commandeered by the Soviet troops) at one end of Schumannstrasse in the city centre.

The East German authorities had every intention of keeping him alive at least until they had extracted from his all the information they could concerning his own interrogation of communists resistance fighters during the war.

Sattler could look forward to a lifelong prison sentence, but for at least as long as the authorities thought they might extract more information from him, his life seems not to have been in immediate danger.

In another file it is recorded that payments from West Germany kept him alive till 1972, as a slightly unconventional case in the context of the [still, in 1972] top secret "Häftlingsfreikauf" programme.

[20] A favoured theory extrapolated from these sources is that the reasons for keeping Sattler alive disappeared after representatives of Chancellor Brandt and First Secretary Honecker signed off on the "Basic Treaty" in 1972 whereby the governments of East and West Germany acknowledged the existence each of the other, reducing invasion fears on both sides.

Now that the two governments were, at some levels, communicating officially, the risk that a former senior Gestapo officer who had been tried and convicted twenty years earlier in respect of a succession of major atrocities, might be found still alive in an East German prison became politically unacceptable.

Despite tantalising glimpses provided by contacts with the older generation, notably the Liberal politician and - as it later transpired, a highly regarded by Markus Wolf - East German spy, William Borm, relocating to India meant that a more systematic investigation of the truth about her father would have to wait.

A reply arrived unexpectedly quickly, stating that the case had been re-examined, and that if the trial had taken place in West Germany, her father would not have received a life sentence.

Researching and reading round what she did know she was able to build her knowledge, early on coming across references to Bruno Sattler having been based in Belgrade at some stage during the war.

She found her father's name in the index and quickly discovered that one of his first administrative tasks, on his arrival in Belgrade, had involved arranging the provision from Berlin of a "Gas van" in order to kill the remaining Jews in the local concentration camp.

Beate Niemann was driven on in her researches by a powerful combination of motives, including an overwhelming conviction that the truths she was uncovering deserved to be confronted without compromise.

Another underlying strand was an angry indignation that came with the growing realisation of the extent to which her mother had repeatedly lied to her about her own father's actions during the war.