David Richard Kaczynski (born October 3, 1949) is the younger brother of Ted Kaczynski, the serial bomber dubbed the "Unabomber" by the FBI before his arrest in 1996. His memoir, Every Last Tie: The Story of the Unabomber and His Family, details his relationship with his brother and parents and the decision that David and his wife made to share their suspicion that Ted was the Unabomber with law enforcement, which led to his arrest.