Peter Buxtun, the whistleblower who revealed that the U.S. government allowed hundreds of Black men in rural Alabama to go untreated for syphilis in what became known as the Tuskegee study, has died. He was 86.

Buxtun died May 18 of Alzheimer’s disease in Rocklin, California, according to his attorney, Minna Fernan.

Buxtun is revered as a hero to public health scholars and ethicists for his role in bringing to light the most notorious medical research scandal in U.S. history. Documents that Buxtun provided to The Associated Press, and its subsequent investigation and reporting, led to a public outcry that ended the study in 1972.