Richard Clarey confessed to over 100 murders starting when he was 15 years old and living in Germany.  Clarey was sentenced to life without parole.

8 1/2" x 11" one page handwritten letter on the back of an original offender daily schedule, hand signed with his last name and prison number, Clarey.
 
Includes the top portion of the original prison stamped mailing envelope with 5 lines of handwritten address by Clarey, hand signed, Richard N. Clarey"