Samuel Allan Kline was a student majoring in physics at the University of Chicago before going to Los Alamos to work as a physicist. While a student at the University of Chicago, Kline worked with Nobel laureate Enrico Fermi in the hidden lab underneath the bleachers at Stagg Field where the world’s first sustained chain reaction took place in December of 1942. He was then recruited to work on the Manhattan Project at Los Alamos. His own family was not aware of his work or his location during this time.
On May 21, 1946, eight men were working on criticality experiments in a remote location in Los Alamos. Kline, then a junior-level physicist, was called over to view the experiment then underway. The experiment went terribly wrong and Kline, who was 10 feet away, received what was then considered a lethal dose of neutron radiation. Louis Slotin, a Canadian physicist who was performing the experiment, died 9 days later due to the radiation exposure. Fortunately, Kline fully recovered and went to Yale law school and practiced patent law for decades. You can find out more about this infamous accident here.