German Resistance Memorial Center
- Biographies

Karl Sack volunteered for military service in 1914 and took part in the First World War. He then continued his law degree and began his career in the 1920s as a district court judge in Hesse. He was married to Wilhelmine Weber from 1922, with whom he had two sons. In 1934 Karl Sack switched to the military justice system. The rapid expansion of the Wehrmacht expedited Sack's career in the Reich War Ministry. He was promoted to an undersecretary in January 1937 and in February 1938 became a court martial council at the Reich Court Martial's senate for treason and high treason cases.

As a judge in the Reich Court Martial, Sack was involved in the investigation leading to the proceedings against Chief of Army High Command Colonel General von Fritsch in 1938. Fritsch was falsely accused of homosexuality, and Sack was able to prove that these accusations were untenable. Through the case, he came into contact with the resistance group in Counterintelligence around Hans Oster and Hans von Dohnanyi and with the military opposition. In the fall of 1942, Karl Sack was appointed head of the army judiciary. He used his position to assist individual members of the resistance and was envisioned in the conspirators' plans as minister of justice in a civilian government. However, he was also an advocate of draconian punishments, especially for deserters, and was involved in a series of death sentences.

After the unsuccessful coup attempt on July 20, 1944, Karl Sack was arrested on September 8, 1944. He was transferred to Flossenbürg concentration camp in February 1945, and murdered there on Hitler's orders on April 9, 1945.