Karl-Heinz Gerstner (15 November 1912 – 14 December 2005) trained as a lawyer and then worked during the war for the German diplomatic service in Paris. Following the war he was released from internment as a Soviet prisoner of war after producing a number of affidavits testifying to his helpfulness to members of the French Resistance during the course of his time at the German embassy in occupied Paris. He was then able to reinvent himself as an East German journalist.

Controversy later emerged, and has persisted, as to the nature and extent of his parallel career as a Stasi informer.

Life Early years and education Karl-Heinz Gerstner was born in the Charlottenburg quarter of Berlin. His natural father was the diplomat Karl Ritter (1883–1968) who later became an ambassador. However, his legal father was actually his step-father, Paul Gerstner (1880–1945), an academic who taught Economics and hoped that his adopted son would grow up to become a statutory auditor. He attended the Kaiser-Friedrich Gymnasium (secondary school) in Berlin between 1917 and 1931. In 1921 he became a member of the Youth Association and Path finder scouting organisations, remaining a member of the latter till 1930. At school, he later recalled, a love of the French language and culture was awakened in him. It was also during this period that he won a public speaking competition staged for Berlin school children by the Library of Congress in Washington. His prize was six months abroad during 1928, as a pupil at the Tabor Academy, a prestigious private school in Massachusetts.

Renewed economic austerity following the Wall Street Crash triggered a period of accelerating political polarisation in Germany, and Gerstner chose the extreme left, in 1931 joining the "German Youth of 1 November 1929" scouting group, which tended to take its lead from the Communist Party. He remained a member till 1932. Fellow members whom he came across at this time included Friedrich Wolf, Harro Schulze-Boysen, Heinrich, Count von Einsiedel and the group's founder, Eberhard Koebel. Between 1931 and 1935 Gerstner studied Jurisprudence at Berlin's Frederick-William University (as the Humboldt was then known). As a student he funded his living costs by working part-time at the foreign-exchange desk of the Deutsche Bank. Towards the end of 1932 he began to take part in evening tutorials held by Kurt Georg Kiesinger.

In 1931 he joined the socialist "Red students group". On 1 May 1933 he joined the Nazi party: he was member number 2,673,178. Party membership had surged since January 1933 when the Nazis took power and lost no time in transforming Germany into a one-party dictatorship. Nevertheless, in his autobiography published in 1999 Gerstner evidently identified an inconsistency which could not go unremarked. He had taken the step, he wrote, only "out of hatred against Hitler ... in order [to do] something against the Nazis" (nur aus "Hass gegen Hitler ...um etwas gegen die Nazis" zu tun). With half an eye on Gerstner's subsequent career as a German diplomat, there were commentators who found the explanation less than persuasive.

It was on the recommendation of the head of the legal department at Deutsche Bank that Gerstner wrote his doctoral dissertation on aspects of the modalities of interbank payments ("Treugiroverkehr"). He received his doctorate of laws from the University of Erlangen in 1937.

Nazi Germany Gerstner passed his Level 1 national law exams in 1935 and embarked on the next stage of the legal traineeship ("Rechtsreferendariat"), starting with six months at the district court in Rheinsberg. That was followed by a six-month period working at a solicitors' office in Berlin that specialised in cases that involved economics, where (despite the growing prevalence of state mandated antisemitism since 1933) two of the senior lawyers were of Jewish provenance. For the next three years, between 1936 and 1939, he worked in Paris and the German foreign trade mission. This appears to have counted, at least initially, as part of his "Rechtsreferendariat" (legal traineeship). Gerstner was marked out for advancement soon after his arrival at Paris trade mission, partly on account of his excellent mastery of the language: the fact that during this time his father became the German ambassador to Brazil may also have counted in Gerstner's favour with German diplomatic staff in Paris. After a few weeks he was offered a permanent position at the newly expanded trade mission, and his status as an "articled law clerk" was apparently suspended or overlooked. In August 1939 all the trade mission staff in Paris were returned to Berlin where Gerstner pursued his legal traineeship, employed as a "Gerichtsassessor" (loosely: "trainee judge"). Gerstner stayed in Germany for around six months. During this time he met Sibylle Boden at a ski resort in the Riesengebirge (literally "Giant Mountains") in southern Silesia. Boden, who later became a highly successful fashion designer, noticed the excellent quality of the suit he was wearing. Evidently there were other mutual attractions, since the two of them would quickly become a couple: in 1945 they married.

In February 1940 Gerstner finally completed his legal training, apparently passing the necessary exams. The simultaneous Invasion of Poland by Nazi Germany and the Soviet Union, launched in September 1939, had triggered the Second World War, and shortly after passing his law exams he received call-up papers requiring him to join the army. However, in the end Gerstner was spared from military service as a result of injuries caused by childhood polio. At the same time the Foreign Ministry offered him a job based on his mastery of the French language, and in April 1940 he started work as a translator in the ministry's radio department. His core responsibilities involved translating "propaganda texts" into French. There is reason to think that even at this stage he was not beyond applying a little ad hoc diplomacy, where appropriate. Working in the broadcasting department of Ribbentrop's Foreign Ministry placed him at the heart of a potentially serious "turf war" with the Propaganda Ministry under Goebbels. Ribbentrop believed that broadcasting propaganda to foreigners was a matter for the Foreign Ministry. Shortly after he joined the department Gerstner was asked by his head of department, Gerhard Rühle, if he could think of anyone with sufficient natural authority to defend the ministry in any possible future conflict with Goebbels. Gerstner thought of, and recommended, his old law tutor, Kurt Georg Kiesinger. Kiesinger had, by this time, already received his call-up papers, requiring him to join the army. However, on 5 April 1940 he was offered and accepted a top job with the increasingly important broadcasting department at the Foreign Ministry. It was essential work which cancelled out the requirement to join the army. In this way, Gerstner played a key role in keeping a future West German Chancellor away from Nazi Germany's wartime frontline.

Wartime in Paris The foreign ministry radio department effectively introduced Karl-Heinz Gerstner to the world of wartime news journalism. Because of his subsequent career as a well-regarded journalist in East Germany Karl-Heinz Gerstner had many more opportunities than most people retrospectively to present his wartime career selectively: there have been suggestions that his enthusiastic pro-government pronouncements, which many sources play down, would have figured more prominently in the record of his wartime career if the war itself had ended differently. Certainly Gerstner's actions in support of the French resistance agenda became anything but covert in 1946, and some, at least, of the more pressing evidence supporting it appears to sourced, directly or indirectly, from his own writings.

France was invaded in May/June 1940. The military phase of the operation was completed much more rapidly than French military planners had expected, and in July 1940 Karl-Heinz was sent back to Paris as an "Academic support assistant in the Economy Department" at the German embassy in Paris. In his own later autobiographical contributions he indicated that this was more a continuation of his previous role than might appear from the job title: he was also keen to stress the difference between members of the permanent diplomatic corps hierarchy and those, such as himself, seconded to the embassy from outside the "civil service" talent pool. In some ways this allowed him a flexibility in interpreting and defining his role which would not have been available to a career diplomat. Reports indicate that his superiors found him to be highly competent, with a useful personal charm and excellent contacts to the local business community that enabled him to provide exceptionally reliable reports. There is an assessment from a relatively unsympathetic commentator that for many practical purposes he quickly came to replace Hans Kuntze, his somewhat "laid-back" head of department.

Gerstner remained in Paris till May 1944. (The city was liberated from German occupation a couple of months later.) He was able to support the French Resistance by secretly passing on information and, especially before 1943, by providing travel permits for the unoccupied southern part of France, thereby rescuing numerous Jewish families facing the threat of deportation to death camps in Germany. During the second half of 1944 and then till the war ended in May 1945 Gerstner was back in Berlin employed, at least officially, at the Foreign Ministry, in the "Special office for news procurement" ("Sonderreferat für Nachrichtenbeschaffung"). It has been suggested - perhaps uncharitably - that this gave him an opportunity to hone a peculiar talent for charming people into providing information that he could then pass on for pecuniary gain, which after 1975 would by of significant value to the East Germany Ministry for Security (Stasi). Other sources refer to his having undertaken "illegal political work" - implicitly on behalf of the still illegal Communist Party - in the Berlin quarter of Wilmersdorf where he had ended up. Fellow antifascists with whom he operated included Leo Dyck, Herbert Eppinger, and Gerhard Fuchs.

Soviet occupation zone