Speculation still swirls around Otto Rahn and his research. From an early age, he became interested in the legends of Parsifal, Holy Grail, Lohengrin, and the Nibelungenlied. While attending the University of Giessen he was inspired by his professor Baron Von Gall to study the Albigensian (Catharism) movement, and the massacre that occurred at Montségur. Rahn is quoted as saying that "It was a subject that completely captivated me''".
Rahn believed it was possible to trace the Cathars, who guarded the Holy Grail in their castle at Montsegur, back to Druids who converted to Gnostic Manichaeism. The Druids in Britain were forerunners of the Celtic Christian Church. He saw that the culture of the medieval Cathar stronghold of Languedoc bore strong a resemblance to the ancient Druids. Their priests were akin to the Cathar Parfaits. The Cathar secret wisdom being preserved by the later Troubadours, the travelling poets and singers of the medieval courts of France-M. Sabeheddin, [Countermedia].
Rahn joined his staff as a junior NCO and became a full member of the SS in 1936. Openly homosexual, he was assigned guard duty at the Dachau concentration camp in 1937 as punishment for a drunken homosexual scrape. He resigned from the SS the following year. He wrote "There is much sorrow in my country. Impossible for a tolerant, liberal man like me to live in the nation that my native country has become." On March 13, 1939 nearly on the anniversary of the fall of Montségur, he was found frozen to death on a mountainside near Söll (Kufstein, Tyrol) in Austria. His death was officially ruled suicide.
Otto Rahn has been described as the inspiration behind the Indiana Jones movie Raiders of the Lost Ark, although George Lucas and Steven Spielberg have never mentioned anything about him being an inspiration to their character. Nazi interest in the Ark of the Covenant and the Holy Grail coincided with the life of this German archaeologist and researcher. Otto Rahn has been the object of many rumors and strange stories including that his death had been faked although all such rumors and stories have been proven false.. Otto Rahn is featured as a character in the 2008 novel The Judas Apocalypse by Dan McNeil, assisting a fellow German archaeologist search for the lost treasure of the Cathars.