Albert Einstein and Margarita Konenkova, a Russian spy (code name: Lukas), ca. 1946.
Margarita Konenkova encountered Albert Einstein at Princeton where her husband had been assigned to sculpt a bust of Einstein. As a spy, her mission was to gather information on the Manhattan Project, which involved the development of nuclear weapons—a project that Einstein himself had recommended to President Roosevelt to initiate. Their romantic relationship was kept under wraps until 1998, when their love letters were unveiled and sold at an auction.
It is said that her objective was to get close to J. Robert Oppenheimer of the Manhattan Project. Einstein did not have a direct role in the Manhattan Project, making it ambiguous what Konenkova exactly aimed to gain through her association with him.