From 1932 to 1972, the US Public Health Service conducted the Tuskegee Study, deliberately withholding syphilis treatment from 399 African American men in Alabama. Even after penicillin became the standard cure in the 1940s, researchers continued the study without treating participants. The men were told they were being treated for 'bad blood.' The experiment was only exposed when AP reporter Jean Heller broke the story in 1972. President Clinton formally apologized in 1997. The same lead researcher ran the Guatemala experiments.