Theodore John Kaczynski aka the "Unabomber" is a former mathematics professor, a domestic terrorist, and serial killer who between 1978 and 1995 killed 3 and wounded 23 others by attempting to start a nationwide combing campaign targeting people involved with modern technology. 
Kaczynski was found dead in his cell on June 10, 2023.
 
Christmas card hand dated November 29, 2015 with a handwritten note on the inside of the card and hand signed twice.
Hand signed at the top, Ted Kaczynski. 
Hand signed again at the close, Ted.

Includes the original prison mailed envelope postmarkec Denver, CO December 2015. The envelope is completely filled out by The Unabomber and  hand signed, Theodore John Kaczynski.