Theodore John Kaczynski also known as the Unabomber, is an American domestic terrorist, anarchist and former mathematics professor.He was a mathematics prodigy, but abandoned his academic career in 1969 to pursue a more primitive life. In 1971, Kaczynski moved to a remote cabin without electricity or running water near Lincoln, Montana, where he lived as a recluse while learning survival skills to become self-sufficient. He witnessed the destruction of the wilderness surrounding his cabin and concluded that living in nature was untenable; he began his bombing campaign in 1978. In 1995, he sent a letter to The New York Times and promised to "desist from terrorism" if the Times or The Washington Post published his essay Industrial Society and Its Future, in which he argued that his bombings were extreme but necessary to attract attention to the erosion of human freedom and dignity by modern technologies that require mass organization.

Kaczynski was the subject of the longest and most expensive investigation in the history of the Federal Bureau of Investigation. The FBI used the case identifier UNABOM (University and Airline Bomber) to refer to his case before his identity was known, which resulted in the media naming him the "Unabomber". The FBI and Attorney General Janet Reno pushed for the publication of Industrial Society and Its Future, which occurred in the Washington Post in September 1995. Upon reading the essay, Kaczynski's brother David recognized the prose style and submitted a tip.

After his arrest in 1996, Kaczynski tried and failed to dismiss his court-appointed lawyers because they wanted him to plead insanity to avoid the death penalty. He did not believe that he was insane. In 1998, a plea bargain was reached under which he pleaded guilty to all charges and was sentenced to life in prison without possibility of parole.

Brief one page handwritten letter written to a pen pal who was seeking information on Kaczynski's writings. Kaczynski has written his name at the top and has also closed by signing his name in full. Original matching handwritten envelope, with Kaczynski's full name and prison address handwritten in the return address field, is also included. Perfect for display. Scarce!