Karl Wirtz was a German scientist who was involved in scientific research. In 1940 he joined the atomic bomb research team led by Werner Heisenberg. Wirtz and his group worked at Haigerloch and by 1945 had gathered together almost sufficient material to build a nuclear weapon.

In April, 1945, Allied forces arrested Wirtz as well as other German scientists such as Otto Hahn, Max von Laue, Carl von Weizsacker, Werner Heisenberg and Walter Gerlach. These men were now taken to England where they were questioned to see if they had discovered how to make atomic weapons.