In her second autobiography "Courting Danger" (released after her death in 1990), Marble mentions that, back in the 1940s, she had married Joe Crowley around World War II, a pilot, who was killed in action over Germany. Only days before his death, she miscarried their child following a car accident. After an attempt to kill herself, she recuperated, and in 1945, agreed to spy for U.S. intelligence. Her mission involved renewing contact with a former lover, a Swiss banker, and obtaining Nazi financial data. The operation ended when a Nazi agent shot her in the back after chasing her while she was trying to escape in a car, but she recovered. Few details of this operation have been corroborated by journalists and authors who tried to investigate this part of her life in the years from the time of her death to the present. No Swiss banker has been discovered, leading to suspicions that this man of mystery might have been a Nazi, someone who Marble may have been trying to avoid having had an association.