In 1963, she was involved in a serious automobile accident in France. For six hours, she lay unconscious, unaware that she nearly lost her right eye. The disfigurement extended to her lip as well. She spent the next two years undergoing plastic surgery, and no damage remained in her face, except for a distinctive curl of her upper lip.
In 1967, she performed the title role in the "utterly calamitous" musical Mata Hari alongside Pernell Roberts. After a preview performance in Washington, D.C. that became infamous for its numerous technical problems, Producer David Merrick, decided to close the doomed production before it reached Broadway.
Mell may be best-known for the role of Eva Kant in Danger: Diabolik (1968). In the late 1990s, the television show MST3K brought the Actress to a new generation of B-movie viewers when the film was featured on the final episode of the series. The show spoofed another of her starring roles in the film Secret Agent Super Dragon.
Mell died in Vienna from throat cancer in 1992, aged 53.