Evidence: Arson
- At the crime scene: metal fragments were found to be covered in white to dark grey deposit later identified as containing sodium carbonate along with amounts of nitrate and sulfur compounds
- FBI lab technicians proposed theory that residue came from dynamite explosion, which would leave residue similar to what was found at the crash site
- Explosion inside the cargo pit of the plane was found to be the point of origin based on the way the supports surrounding the area were bent outward, and how the foreign residue found was left in a roughly circular area around the proposed origin site.
- Contents of the cargo pit, however, showed no flammable or explosive items were present in that area of the plane.
- At the crash site, 5 pieces of sheet metal were found, all heavily covered in the soot like substance. One piece was red in color and bore the inscription “HO” on it.
- It was determined the pieces of metal belonged to a 6 volt battery that was used as the detonator for the explosives on the plane.
- Before her departure, Graham gave his mother a gift as a going away gift, although investigators believe that gift contained the dynamite used to commit the crime.
General Arson Evidence
- The goals in arson investigations are to determine a point of origin and whether the fire was caused by an explosion or ignition source
- Ash and soot found at crime scenes can be analyzed for the presence of chemicals and accelerants
- Bomb investigations look for piece of a detonator and pieces of the bomb are analyzed for evidence of the kind of bomb it may be
- Investigators also look at the kind of person who could have built such a bomb