Some facts about bombs. First, definitions. A low explosive is one that burns, usually at a set rate. A good example is black powder, which is typically used for fuses. High explosives are ones that actually explode. They often need a trigger, either shock or heat, to set off the explosion. The most example is nitroglycerin. Nitroglycerin was developed in 1847 but it was highly unstable, meaning that it would explode over the littlest thing: heat rising a few degrees or a slight shock wave as a person walked. Alfred Nobel (yes, the same Nobel as in Nobel Peace Prize) wanted to nitroglycerin so it could be put to more commercial applications. He accomplished this feat in 1867 by mixing it with diatomaceous earth. It was called dynamite. Now, nitroglycerin is used in much smaller quantities in our current dynamite and similar explosives. Today, nitrocellulose or ammonium nitrate is mixed with nitroglycerin. The military expanded applications by creating trinitrotoluene (TNT) and plastic explosives (C-3 and C-4).
Second, bomb scene investigation is very risky regardless of whether or not the bomb has exploded. More people are needed to respond at the scene. The site may be more unstable. Secondary explosions may occur. More gawkers show up. The investigators need to ask many questions that are similar to those questions that arson investigators ask. They need to know who made the bomb; where was it assembled; what materials were involved and where can they be purchased; where was the bomb located and why; why was it detonated (or not detonated); who or what was the intended target? Investigators need to find the focal point of a detonated bomb. This is called the seat. Many of the materials will be in this area and it will help with determination of the site stability. Bombers search for undetonated bombs by listening for a detonation device or timer. Visual searches are done first, by an individual trained to see things that are out of place. Nothing is moved on the first search. The individual should start on floor level, where there is more likelihood of sending a shock wave that will detonate the bomb. Next, the investigator should look waist to eye level and finally up to the ceiling. All fixtures need to be checked for signs of tampering. When the visual circuit is done, everything is carefully open or moved to thoroughly verify the presence of any bombs.
Let's do some profiling (traits that show characteristics) about bombers.
Juvenile bombers are typically white males from all social backgrounds who are just experimenting. They think it is fun to blow things up and often find out the hard way how dangerous that can be. Hundreds of children tend to maim or kill themselves by experimenting with bombs. Adult bombers have a few more traits to look at. Profiling begins with the bomb threat. The threat can help identify the bombers age, gender, upbringing, nationality or regionality, emotional stability, and education levels. Adults make bombs for one of four reasons: show off skill, desire to attract attention, anger at a specific group, or politics/religion. Bombers can be categorized into three main groups. The first are those attracted to destruction. They are power-motivated and get a thrill from threatening people and destroying property. They tend to goad and warn so that they are recognized. The second group are mission-oriented. They are attracted to designing, making, and placing the bomb. They are excited by the process rather than the end result. The final group are Technicians. Their thrill is a gratification in how "brillant" they are in designing and building their bombs. They often want their bombs found so that everyone can know how clever they were in their construction. All adult bombers share similar profiles, though, which are listed here:
Usually refers to a "we" but is often working alone
average to above average intelligence but underachieve; inadequate personality
neat, orderly, meticulous, careful planners
nonathletic, nonconfrontational, and cowardly