However, several eyewitnesses at the prison camp, including Valentin Hartig and Hans Siemsen, reported that Münzenberg remained in high spirits both during his days at Chambaran and in the first days of his flight to freedom after which they lost sight of their comrade.McMeekin, pp. 369–370: Only one alleged witness, Heinz Hirth, who first reported his version of Münzenberg's death in 1945 in a special report to the postwar KPD, asserted that the latter was suffering "extraordinary nervous tension". Hirth, who stated that he joined up with Münzenberg "in order to keep watch on him" stated that Münzenberg belatedly acknowledged his deviation from the party, confessing to Hirth that "he had committed very great errors that he could never make good", whereupon he began crying uncontrollably. Hirth claimed that the very next day he found Münzenberg's body hanging from a tree. Another theory is that Münzenberg was killed by German agents working for the Gestapo, who had apparently infiltrated his organization in 1939. One of the most notable documents in the Bundesbeauftragte für die Stasi-Unterlagen ("Federal Commission For Stasi Documents") archive is a letter referring to information obtained from the prewar Deutsches Institut für Militärgeschichte files in Potsdam. On 10 June 1969, the head of Hauptabteilung I, Generalmajor Kleinjung (de), wrote to Erich Mielke, then Minister of State Security, The letter stated that there was proof that a secret agent of the Gestapo with the code name V 49 had infiltrated Münzenberg's group in 1939. The identity of the agent remains unknown. The widely circulated theory that he was executed by the NKVD was also countered by the theory of Wilhelm Leo's son, Gerhard, in his reminiscences of the French Resistance: that Wilhelm Leo escaped the Chambaran Internment Camp with Münzenberg and confirmed that he committed suicide, as confirmed by French investigators. Arthur Koestler wrote in 1949 about the death of Willi Münzenberg: He "was murdered in the summer of 1940 under the usual lurid and mysterious circumstances; as usual in such cases, the murderers are unknown and there are only indirect clues, all pointing in one direction like magnetic needles to the pole" Further reading Christopher Andrew and Oleg Gordievsky, KGB: The Inside Story of its Foreign Operations from Lenin to Gorbachev. London: Hodder & Stoughton, 1990. Babette Gross, Willi Münzenberg: A Political Biography. Translated by Marian Jackson. East Lansing: Michigan State University Press, 1974. Arthur Koestler, The Invisible