Crime Library: Criminal Minds and Methods

The Genius Bomber: The Mormon Forgery Murders

Bomb Investigation

Bombs are cheap to build and easy to hide or disguise as something else, like an innocent package.   Yet theyre potentially more lethal than most other types of weapons.  The explosion is the result of a rapid expansion of gases from a chemical charge.  A power source causes a shock, heat or friction to start the reaction.  The substance breaks its chemical bonds to release the gases.  Until it equalizes with surrounding air, a powerful wave of pressure shoots out and destroys everything in its path, except perhaps objects very close to the point of explosion.   But its not over.  Then comes a negative phase in which the gasses draw back and that can cause further damage. 

Bomb
Simple image of a make-shift bomb.

The explosive limit is the upper and lower concentrations of air and gas mixture that will support combustion.   The most hazardous fuels are those with the broadest explosive limits.  Yet the impact will depend more on the bombs actual placement than on its size.  A bomb that fits inside a transistor radio, if taken aboard a plane, will do more damage than a thousand-pound explosive placed in a building with a dense structure that may hinder its force.

There are many types of explosives available, from weed killer to picric acid, and they can be triggered by raising the unstable compounds component temperature with a shock, a match, or an electrical discharge.   The detonation waves may rise to thousands of degrees Fahrenheit and produce pressure up to 1,200 tons per square inch.

Techniques of Crime Scene Investigation
Techniques of Crime Scene Investigation

To control a bomb until it is placed, its put into some type of casing.   Bombs are commonly placed inside metal pipes, called pipe bombs.  Completing a circuit between the power source and the explosive compound, the bomb maker uses relays, shunts, timers and switches.

When investigating, the bomb squad follows a specific procedure, as outlined in Barry Fishers Techniques of Crime Scene Investigation

They will try to determine

  • the materials used to make the bomb
  • the skill level of the bomb maker
  • the bombs target
  • the degree of criminal intent
  • the location of the bombs construction
  • the means by which it was conveyed to its location
  • the place from which the bomb maker acquired the parts
  • how the bomb was detonated
  • where its seat is
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