page_title: United Airlines Flight 629
section_title: Investigation
hierarchical_section_title: United Airlines Flight 629 / Investigation
caption_attribution_description: English: The wreckage of United Flight 629 was carefully laid out in a Denver warehouse after its bombing.
context_page_description: United Airlines Flight 629, registration N37559, was a Douglas DC-6B aircraft also known as "Mainliner Denver", which was blown up with a dynamite bomb placed in the checked luggage on November 1, 1955. The explosion occurred over Longmont, Colorado, United States at about 7:03 p.m. local time, while the airplane was en route from Denver, Colorado to Portland, Oregon and Seattle, Washington. All 39 passengers and 5 crew members on board were killed in the explosion and crash.
  Investigators determined that John "Jack" Gilbert Graham was responsible for bombing the airplane to kill his mother as revenge for his childhood and to obtain a large life insurance payout. Within fifteen months of the explosion, Graham—who already had an extensive criminal record—was tried, convicted, and executed for the crime.
context_section_description: The investigation, by the Civil Aeronautics Board, determined that the aircraft began to disintegrate near the empennage, or tail, and that the aft fuselage had been shattered by a force strong enough to cause extreme fragmentation of that part of the aircraft. The explosion had been so intense that investigators thought it unlikely to have been caused by any aircraft system or component. There was also a strong smell of explosives on items from the number 4 baggage compartment (which was at the back).
  Suspicions that a bomb had been placed in luggage loaded aboard the aircraft were fueled by the discovery of four pieces of an unusual grade of sheet metal, each covered in a gray soot. Further testing of the cargo pit showed that each piece was contaminated with chemicals known to be byproducts of a dynamite explosion, the origin of which was believed to be a passenger's luggage.
  The Federal Bureau of Investigation, certain that the aircraft had been brought down by a bomb, performed background checks on the passengers. 
  In the earlier stages of the investigation, the investigators discovered at the time of the crash, United Airlines management was locked in a dispute with a local airline union, leading to the theory that the bombing of Flight 629 was a attempt to damage the United Airline's reputation, this theory was later excluded from the investigation. 
  After the initial checks, they focused their efforts on Denver locals citing that they may have personal enemies. A few passengers had purchased life insurance at the airport just before boarding. One such insuree, as well as local, was Daisie Eldora King, 53, a Denver businesswoman who was en route to Alaska to visit her daughter. When agents identified her handbag, they found a number of newspaper clippings containing information about King's son, John Gilbert Graham, who had been arrested on a forgery charge in Denver in 1951. Graham, who held a grudge against his mother for placing him in an orphanage as a child, was the beneficiary of both her life insurance policies and her will. Agents also discovered that one of Mrs. King's restaurants, the Crown-A Drive-In in Denver, had been badly damaged in an explosion; Graham had insured the restaurant and then collected on the property insurance following the mysterious blast.
  Subsequently, agents searched Graham's house and automobile. They found wire and other bomb making parts in the garage, which were identical to those found in the wreckage. They also found an additional $37,500 ($357,900 today) in life insurance policies; however, Mrs. King had not signed either these policies or those purchased at the airport, rendering them worthless. Graham told FBI agents that his mother had packed her own suitcase. However, his wife, Gloria, revealed that Graham had wrapped a "present" for his mother on the morning of the day of Mrs. King's ill-fated flight.
  Faced with the mounting evidence and discrepancies in his story, on November 13, 1955, Graham finally confessed to having placed the bomb in his mother's suitcase, telling the police:
  I then wrapped about three or four feet of binding cord around the sack of dynamite to hold the dynamite sticks in place around the caps. The purpose of the two caps was in case one of the caps failed to function and ignite the dynamite ... I placed the suitcase in the trunk of my car with another smaller suitcase...which my mother had packed to take with her on the trip.
caption: The wreckage of United Flight 629 was carefully laid out in a Denver warehouse after its bombing.
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