Charles Manson written while he was at the California Medical Facility in Vacaville, California. 
8 1/2" x 11" two page letter discussing tapes which he had sent to someone in Boston that did not keep their word and much more incredible content, hand signed, Charles Manson.
Manson sent this letter on to a friend and asked them to send the letter and it includes the mailing envelope written in an unknown hand, postmarked Houston, TX July 8, 1985.

Charles Manson Incredible Letter Signed with Envelope