Martin Sommer was one of the most feared SS guards at Buchenwald concentration camp, where he became known as the “Hangman of Buchenwald.” In charge of the notorious punishment block known as the Bunker, Sommer tortured and murdered prisoners through beatings, injections, starvation, and other methods. One of his specialties was suspending prisoners by their wrists from trees—a torture method that became known as the “singing forest” because of the victims’ screams.

Sommer’s treatment of prisoners eventually became the subject of an internal SS investigation, and he was sent to a penal unit on the Eastern Front. After the Second World War, he spent years in Soviet captivity before returning to West Germany. In 1958, Sommer faced trial for his crimes at Buchenwald and was sentenced to life imprisonment for the murder of at least 25 prisoners.