Rolf Mueller was a sadistic pedophile working out of a German circus in the early 20th Century as a Strongman, kidnapping, torturing, and murdering scores of children. In 1920, he kidnapped a young blonde boy named Josef who became his protege and victim.

He joined the Nazi Party in the 1930's and was charged with an orphanage in Lindz where he was free to abuse, conduct experiments on, and vivisect the orphans. He was shot and wounded by a young orphan named Ursala Zandt, the future Silhouette as he was cutting up her younger sister, Blanche. Zandt and the orphanage's nurse and pharmacist Gretchen then escaped. Josef escaped as well.

By 1938, Mueller had become a liability and was deported. He eventually became a Strongman for the Big Top Circus in the United States where his murders continued. Silhouette, suspecting that Hooded Justice was Mueller began investigating the kidnappings and murders, eventually leading her, Night Owl, and Mothman to track down the apartment where he tortured and murdered.

In 1946, he tracked down and murdered Ursula and Gretchen, framing the supervillain Liquidator in his stead. He continued his crimes off the radar, possibly conducting work for the Soviets until he entered Night Owl's, Mothman's, and The Comedian's radars, all of whom suspected him of being Hooded Justice based on Ursula and Gretchen's notes. The Comedian got to him first on orders from HUAC to expose and Hooded Justice as a Communist and serial killer only to realize the truth. Mueller was killed by the Comedian and dumped into the ocean. The truth of his relationship to the Watchmen was redacted out of Under The Hood by Hollis Mason under threat. Years later, the New Frontiersman printed an article suspecting Mueller of being Hooded Justice.