 As bombing an airliner is a federal crime in the United States , the FBI became involved after this incident and derived the code name UNABOM ( UNiversity and Airline BOMber ) . U.S. Postal Inspectors , who initially had the case , labeled the suspect the " Junkyard Bomber " because of the material used to make the mail bombs . In 1979 , an FBI @-@ led task force that included the ATF and U.S. Postal Inspection Service was formed to investigate the case . The task force grew to more than 150 full @-@ time investigators , analysts , and others . This team made every possible forensic examination of recovered components of the explosives and studied the lives of victims in minute detail . These efforts proved of little use in identifying the suspect , who built his bombs essentially from " scrap " materials available almost anywhere . The victims , investigators later learned , were chosen irregularly from library research . 
