prisoners testify on his behalf, was the only person to be acquitted. Other former staff were hanged for war crimes in the Dachau Trials and the Belsen Trial, including camp leaders Josef Kramer, Franz Hössler, and Vinzenz Schöttl; doctor Friedrich Entress; and guards Irma Grese and Elisabeth Volkenrath. Bruno Tesch and Karl Weinbacher, the owner and chief executive officer of the firm Tesch & Stabenow, one of the suppliers of Zyklon B, were arrested by the British after the war and executed for knowingly supplying the chemical for use on humans. The 180-day Frankfurt Auschwitz trials, held in West Germany from 20 December 1963 to 20 August 1965, tried 22 defendants, including two dentists, a doctor, two camp adjudants and the camp's pharmacist. The 700-page indictment, presenting the testimony of 254 witnesses, was accompanied by a 300-page report about the camp, Nationalsozialistische Konzentrationslager, written by historians from the Institut für Zeitgeschichte in Germany, including Martin Broszat and Helmut Krausnick. The report became the basis of their book, Anatomy of the SS State (1968), the first comprehensive study of the camp and the SS. The court convicted 19 of the defendants, giving six of them life sentences and the others between three and ten years. East Germany also held trials against several former staff members of Auschwitz. One of the defendants they tried was Horst Fischer. Fischer, one of the highest ranking SS physicians in the camp, had personally selected at least 75,000 men, women, and children to be gassed. He was arrested in 1965. The following year, he was convicted of crimes against humanity, sentenced to death, and guillotined. Fischer was the highest-ranking SS physician from Auschwitz to ever be tried by a German court. Legacy In the decades since its liberation, Auschwitz has become a primary symbol of the Holocaust. Historian Timothy D. Snyder attributes this to the camp's high death toll and "unusual combination of an industrial camp complex and a killing facility", which left behind far more witnesses than single-purpose killing facilities such as Chełmno or Treblinka. In 2005 the United Nations General Assembly designated 27 January, the date of the camp's liberation, as International Holocaust Remembrance Day. Helmut Schmidt visited the site in November 1977, the first West German chancellor to do so, followed by his successor, Helmut Kohl, in November 1989. In a statement on the 50th anniversary of the liberation, Kohl said that "[t]he