Chapter 11 FORENSIC ASPECTS OF ARSON AND EXPLOSION

1. Chapter 11FORENSIC ASPECTS OF ARSON AND EXPLOSION

2. Introduction • Arson and explosions often present complex and difficult circumstances to investigate due to the fact that the perpetrator has thoroughly planned the act, is not present during the act, and the destruction is so extensive. • The criminalist’s function is rather limited to detecting and identifying relevant chemical materials collected at the scene and reconstructing and identifying ignitors or detonating mechanisms. ARSON AND EXPLOSION

3. Flammable Range Flammable range is the ratio fuel vapor and air expressed as a percentage (i.e. 1.5% vapor to air) Flammable range of gasoline is 1.5% to 7.6%. What does this mean? FOR GASOLINE: • 1.5 is the Lower Limit of flammable range (LLF) • This is referred to as a LEAN MIXTURE • More fuel efficient • Burns hotter • 7.6 is the Upper Limit of flammable range • This is referred to as a RICH MIXTURE • Less fuel efficient • Burns cooler Is the gasoline we put in our cars Lean or Rich? ARSON AND EXPLOSION

4. Flammable Range = Explosion Limit When a gasoline/air mixture reaches explosion limit from the lower end (LEL) and an ignition source is present, the mixture instantaneously combusts. If this type of gas mixture is contained it will EXPLODE. LEL + ignition  EXPLOSION If the gasoline/air mixture reaches the explosion limit from the upper end (UEL) it will produce both an EXPLOSION and a FIREBALL. UEL + ignition  EXPLOSION + FIREBALL UEL explosions tend to be less survivable than LEL explosions Gas stove/cigarette example…LEL or UEL? ARSON AND EXPLOSION

5. Video • Destroyed in seconds: http://www.youtube.com/watch?v=5NGT4vph0sU&feature=fvwrel

6. EXPLOSIVES • The difference between fires and explosions is the speed at which the oxidation-reduction reaction occurs • Most explosives use chemical oxidizers rather than oxygen from the air

7. Explosions • Explosives are substances that undergo a rapid oxidationreaction with the production of large quantities of gases. • It is this sudden buildup of gas pressure that constitutes the nature of an explosion. • The speed at which explosives decompose permits their classification as high or low explosives. • The most widely used explosives in the LOW EXPLOSIVE group are: • gas mixtures • black powder (potassium/sodium nitrate, charcoal and sulfur) • smokeless powder (nitrocellulose or combination nitrocellulose and nitroglycerin) ARSON AND EXPLOSION

8. High Explosives • High explosives • Primary explosives • ultrasensitive to heat, shock, or friction • provide the major ingredients found in blasting caps or primers usually used to detonate secondary explosives • Secondary explosives • relatively insensitive to heat, shock, or friction and will normally burn rather than detonate if ignited in small quantities in the open air • High Explosives comprise the majority of commercial and military blasting, such as dynamite, TNT, PETN, and RDX ARSON AND EXPLOSION

9. High Explosives • Nitroglycerin is so shock sensitive that it is generally considered too dangerous to handle! • Alfred Nobel found a way to stabilize it with diatomaceous earth, rendering it insensitive to shock • Diatomaceous earth has since been replaced with sawdust.

10. The Explosive Market • In recent years, nitroglycerin-based dynamite has all but disappeared from the industrial explosive market and has been replaced by ammonium nitrate-based explosives (i.e., water gels, emulsions, and ANFO explosives). • In many countries outside the United States, the accessibility of military high explosives to terrorist organizations makes them very common constituents of homemade bombs. • RDX is the most popular and powerful of the military explosives, often encountered in the form of pliable plastic known as C-4. ARSON AND EXPLOSION

11. Collection and Analysis • The entire bomb site must be systematically searched with great care given to recovering any trace of a detonating mechanism or any other item foreign to the explosion site. • Objects located at or near the origin of the explosion must be collected for laboratory examination. • Often a crater is located at the origin and loose soil and other debris must be preserved from its interior for laboratory analysis. • One approach for screening objects for the presence of explosive residues in the field or laboratory is the ion mobility spectrometer (IMS). ARSON AND EXPLOSION

12. Bomb Investigation • Deam building structurally safe (no 2nd explosive) • Find the “seat of the blast” usually the site of a large crater • Spiral outward in growing circles to search for trace evidence in debris • First ½ inch of soil and debris should be removed and collected in metal or glass containers as well as any soft materials • DO NOT MAIL to the lab • Immovable objects should be swabbed with acetone • Find metal or explosive wrapping with date shift codes to link back to manufacturer

13. Collection and Analysis • Preliminary identification of an explosive residue using the IMS can be made by noting the time it takes the explosive to move through a tube. A confirmatory test must follow. • All materials collected for the examination by the laboratory must be placed in sealed air-tight containers and labeled with all pertinent information. • Debris and articles collected from different areas are to be packaged in separate air-tight containers. • It has been demonstrated that some explosives can diffuse through plastic and contaminate nearby containers. ARSON AND EXPLOSION

14. Back at the Lab • Typically, in the laboratory, debris collected at explosion scenes will be examined microscopically for unconsumed explosive particles. • Recovered debris may also be thoroughly rinsed with organic solvents and analyzed by testing procedures that include color spot tests, thin-layer chromatography, high-performance liquid chromatography, and gas chromatography-mass spectrometry. • Confirmatory identification tests may be performed on unexploded materials by either infrared spectrophotometry or X-ray diffraction. ARSON AND EXPLOSION

15. Taggants • Taggants used to ID bombs (2 kinds) • Pre-blast taggants (ID before explosion) • Post blast taggants (designed to survive the blast) • Taggants the size of a grain of pepper are magnetic and fluorescent and contain minislabs of color detectable by microscopes • US tested the practicality of putting taggants in commercial explosives but when the program ran out, taggant programs were stopped. • Due to increased concern with terrorism, US has taken a second look at using taggants.

16. World Trade 1993 http://www.enotes.com/forensic-science/world-trade-center-1993-terrorist-attack

17. Friday, February 26, 1993 • Killed 6, Injured 1000 • Parking garage, 100-foot crater several stories deep and several more high • Task force believed Islamic fundamentalists were behind the terror attack • VIN number on obliterated vehicle – rented – tried to get $400 deposit back • Apartment had bomb materials and cyanide enough to kill a town • Tried, convicted and sentenced to life • RamziYousef behind bombings, along with 7th plotter still at large: Abdul Yasin

18. 2500 tons of rubble removed • By March 29th, full access to WTC was restored • “It felt like an airplane hit the building.” – Bruce Pomper, eyewitness

19. Unabomber – Ted Kaczynski Harvard at 16

20. 18-yr long pen-pal bombing spree • 16 bombs, Killed 3, injured 29 • Unabomber – UNABOM – university and airline • FC – “Freedom Club”; left false clues • Transcendentalist motives – • The main argument of "Industrial Society And Its Future" is that technological progress is undesirable, can be stopped, and in fact should be stopped in order to free people from the unnatural demands of technology, so that they can return to a happier, simpler life close to nature. Kaczynski argued that it was necessary to cause a "social crash", before society became any worse. He believes a collapse of civilization is inevitable, and thus, it is best to end things now, rather than later.

21. “Manifesto” published • David Kaczynski (brother) came forward recognizing his brother’s writing

22. Shoe Bomber – Richard Reid

23. Shoe Bomber Continued • Life without parole, super maximum security prison (ADMAX)

24. OklahomaCity Bombing, 1995 • http://en.wikipedia.org/wiki/Oklahoma_City_bombing

25. Alfred P. Murrah Federal Building, 4/19/95 • 168 killed (19 <6yoa), 680+ injured • <90 min – McVeigh caught driving without a license plate and carrying an unlawful weapon • Gulf War Vet • Detonated Ryder Truck bomb, equiv. 5000lb TNT • Felt 55 miles away; 3.0 on Richter Scale • McVeigh executed June 11, 2001 • Accomplice: Terry Nichols, life in ADMAX

27. Envelope with pages from The Turner Diaries—a fictional account of white supremacists who ignite a revolution by blowing up the FBI headquarters at 9:15 one morning using a truck bomb • Wore a printed T-shirt with the motto of the Commonwealth of Virginia, Sic semper tyrannis ("Thus always to tyrants", which was shouted by John Wilkes Booth immediately after the assassination of Abraham Lincoln) and "The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants" (from Thomas Jefferson) • Envelope with bumper sticker with Thomas Jefferson slogan, "When the government fears the people, there is liberty. When the people fear the government, there is tyranny." Underneath, McVeigh had scrawled, "Maybe now, there will be liberty!" • Hand-copied quote by John Locke asserting that a man has a right to kill someone who takes away his liberty. • Waco and Ruby Ridge

28. Before his execution, McVeigh said that he did not know a day care center was in the building and that, had he known, "It might have given me pause to switch targets." • FBI disagrees since he cased the building months prior