took many years to determine, and was finally unravelled in the 1980s by Austrian historian Ernst Kubin. The plan was devised by Dr. Emmerich Pöchmüller, the general director of the mine, Eberhard Mayerhoffer, the technical director, and Otto Högler, the mine's foreman. It was sanctioned by Ernst Kaltenbrunner, an SS officer of high rank in the Gestapo who had grown up in the area, and was later convicted of mass-murder and hanged. The plan was carried out by the miners, with the tacit approval of Eigruber's guards, several of whom had been persuaded by Karl Sieber, an art restorer who had worked on paintings stored in the mine, that destroying the artwork and the mine was not a good idea. The entire operation took three weeks to implement. On 5 May the signal was given, and six tons of explosives with 386 detonators and 502 timing switches were activated, causing 66 blasts which closed off 137 tunnels. The blockages took about a month to clear away totally, although a hole big enough for a man to sidle through was completed by the miners overnight after the Americans arrived. Due to geo-political considerations, U.S. forces were ordered to pull back from the territory which included Altaussee, as it had been determined that it would be part of the Russian zone of occupation. Because of this, the paintings and artworks in the mine were removed and transferred elsewhere in about two weeks, rather than the year which had originally been planned. Most of the approximately 12,000 pieces of art in the mine were recovered. The Altaussee trove included both works meant specifically for the Führermuseum and other looted artwork as well. Other caches of art not intended for Linz were recovered in places throughout the Reich; there were over 1000 repositories in southern Germany alone,. although some of the artworks in them came from the collections of German museums – these were eventually returned. Much of Göring's collection from his estate at Carinhall was discovered in a cave at Berchtesgaden, where he had a summer home near Hitler's Berghof retreat, part of it was also left in his private train, which was found in Unterstein, and had been looted by the local residents. Looting of the Munich repository Part of the collection designated for the Linz museum was stored in the air raid shelters of the Führer Building in Munich, part of