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 who killd himself was found dead in his cell on June 10, 2023. 
 
Envelope postmarked October 2, 2015 and completely written by Kaczynski. Hand  signed in full, Theodore John Kaczynski.