Charles Manson learned his most effective techniques by studying Dale Carnegie.
After stealing a car in Ohio and driving it to L.A., where his mother was living, Manson was sent to prison in San Pedro -- and there he enrolled in a Carnegie course. It changed his life.
"Charlie had always evinced limited reading skills, but in this Carnegie class he proved that he could not only read but fully comprehend printed material if he was sufficiently engaged, and if instructors were helpful enough," Guinn writes. "Virtually every word in the Carnegie publications resonated with Charlie. For the first time in his life he was considered an outstanding pupil." How to Win Friends, Guinn reports, "seemed to formally codify all the ways Charlie had manipulated people since childhood." Acquaintances would later recall Manson using just those techniques on the young women in his "family."
http://blogs.laweekly.com/informer/2013/08/charles_manson_jeff_guinn.php