sentences:  In 1942, the sixth Surgeon General of the United States, Thomas Parran, Jr., endorsed medical experiments on STD transmission so long as volunteers were found to be exposed to infection.In 1943, a decision was made to use prisoners as volunteers, as soldiers could not be guaranteed sexual abstinence for six months, and the mentally ill were not considered appropriate research subjects.Due to legal issues, the Army Medical Corps preferred federal prisons to state run institutions, and Terre Haute had the best medical facilities.