The mastermind, Ramzi Yousef, was ultimately captured in Pakistan in 1995. He was planning an attack on the U.S. involving airplanes. His uncle, Khalid Sheikh Mohammed, later became the alleged mastermind behind the Sept. 11 terror attacks.
Ted Kaczynski, known as the "Unabomber," is now almost a household name. But during the 20-year investigation following his first bomb at the University of Illinois at Chicago in 1978, he was the perfect anonymous killer.
During his 17-year bombing spree he killed three Americans, injured 24 and instilled widespread fear and panic with threats to blow up airliners in flight. His nickname is derived from the 1979 task force created to investigate his crimes, called "UNABOM" for the UNiversity and Airline BOMbing targets involved.
Forensic examinations were virtually useless, as Kaczynski was extremely careful to avoid leaving clues by creating bombs from untraceable scrap materials available anywhere. And his victims were targets randomly chosen from library research.
In 1995 the Unabomber sent the FBI a 35,000-word essay detailing his motives and objections to modern society. Despite initial hesitations, the FBI released the manifesto to the public, and David Kaczynski contacted the FBI and suggested it might have been written by his troubled brother Ted. On April 3, 1996, the FBI arrested Kaczynski in his 10-foot-by-14-foot cabin near Lincoln, Mont., where they found an arsenal of bomb components, 40,000 revealing journal pages and one live bomb.
Kaczynski pleaded guilty and was sentenced to life in isolation at a "Supermax" prison in Colorado.
Jonestown Cult Murder-Suicide
Jonestown was a makeshift settlement of more then 900 people in the jungle of Guyana created by Jim Jones and his cult-like following, called the People's Temple.
Reports began to surface about the group, suggesting abuse, forced labor, imprisonments, the use of drugs to control behavior, suspicious deaths and mass suicide rehearsals.
In November 1978, California Rep. Leo Ryan brought the press to check out the rumors and learned that many members wanted to leave with Ryan. The congressman ordered two planes to bring the entire group to escape together, but as they assembled on the airstrip, armed men from Jonestown emerged in trucks, opening fire on one plane while one member of the sect, Larry Layton, began shooting from inside the plane.
Ryan and many others were killed. Arguing that their attack on the planes would bring Jonestown residents harm, Jones persuaded more then 900 sect members — including more than 200 children — to drink a fruit drink laced with cyanide.
Along with the poisoned followers, Jones was found dead, with a gunshot wound to the head. An extensive investigation involving the few survivors of the Jonestown disaster led to the arrest of Larry Layton, who was the only member of the Peoples Temple tried in the U.S. for crimes at Jonestown. He was sentenced to life in prison.
The 1963 Birmingham Baptist Church Bombing
On Sept. 15, 1963, a dynamite bomb exploded in a Birmingham, Ala., Baptist Church, killing four African-American girls and injuring more than 20 others inside.