Analysis of Explosives

1. Analysis of Explosives Ms. Scribner’s Forensic Science Class—Eisenhower High School

2. Introduction • Most bombing incidents involve homemade explosive devices • There are a great many types of explosives and explosive devices • Lab must determine type of explosives and, if possible, reconstruct the explosive device

3. Explosives • Combustion (or decomposition) of explosives occurs so rapidly, that there isn’t enough time for the oxygen in the surrounding atmosphere to combine with the fuel. • Therefore, many explosives must have their own source of oxygen – or oxidizing agents

4. Definitions • Explosion—sudden release of chemical or mechanical energy caused by an oxidation or decomposition reaction that produces heat and a rapid expansion of gases.

5. Definitions • Reagent—a substance used to produce a chemical reaction to detect, measure, or produce other substances. • Spot tests can be administered to identify

6. IED--An improvised explosive device is a bomb constructed and deployed in ways other than in conventional military action. It may be constructed of conventional military explosives, such as an artillery round, attached to a detonating mechanism. IEDs are commonly used as roadside bombs.

7. Chemistry of Explosion • Essentially a combustion reaction - like a fire • Major difference is speed of reaction • Damage caused by rapidly escaping gases and confinement

8. Definitions • High explosives—chemicals that oxidize extremely rapidly, producing heat, light and a shock wave; will explode even if not confined • Low explosives—chemicals that oxidize rapidly, producing heat, light, and a pressure wave; will explode only when confined.

9. Types of Explosives • Low explosives • Escaping gases up to about 3000fps (foot per second) • Crucial element is physical mixture of oxygen and fuel • Examples are black and smokeless powders • Black powder is mixture of potassium nitrate, charcoal and sulfur • Smokeless powder is nitrocellulose and perhaps nitroglycerine

10. Types of Explosives • High explosives • Velocity of escaping gases up to 10,000fps • Oxygen usually contained infuel molecule • Two types • Initiating - Senistive, will detonate readily when subjected to heat or shock. Used to detonate other explosives in explosive train • Noninitiating - relatively insensitive, requires heat or shock. Includes TNT or PETN

11. Classification by Use • Commerical Explosions: Ammonium Nitrate fuel oil (ANFO), black powder, dynamite • Military Explosions: RDX (commonly known as C-4), PETN, PETN mixed with TNT to make grenades • IED—low explosives placed into confinded containers

12. Ammonium nitrate based • Water gels • Emulsions--are intimate mixtures of oxidizers and carbonaceous fuels made as water in oil type of Emulsions used for blasting in quarries, stripping in underground metal mines, tunneling, well sinking, and road construction . • ANFO’s--ammonium nitrate/fuel oil) is a widely used bulk industrial explosive mixture

13. Analysis of Explosives • Microscopy • Thin layer chromatography • Visualise with Greiss reagents • Infrared spectrophotometry • Detonator fragments

14. Microscopic Examination • Perforated disc • Tube • Ball • Disc • Rod • Lamel

15. 1, 2, and 3 step Explosive Trains Explosive Trains

16. The Role of Forensic Science in the Investigation of Major Acts of Terrorism

17. A forensic science technician, also referred to as a criminalist, gathers, interprets and analyzes evidence using forensic science techniques and tests. • Analyze and test tissue samples • Test chemical substances and physical materials • Interpret lab findings • Collect criminal evidence • Reconstruct crime scenes • Testify as expert witness during trials

18. First World Trade Center Bombing

19. 1993 The Scenario—first bombing attempt • Urea nitrate bomb put into truck and driven into underground WTC garage and parked at 4th level down • Subsequent explosion did extensive damage to several levels of the garage and less damage to other levels • Although goal was to topple WTC, little structural damage was done • Some loss of life

20. Goals of Investigation • Identify victims • Identify explosive • Recover bomb and timing device • Determine method of delivery

21. Evidence Sought • Investigators had to remove large quantities of concrete, steel and cars to get to bomb seat • Bomb seat contained most of the important evidence • Bomb parts; timer, casing, etc. • Explosive residue • Parts of truck that contained explosive

22. Areas of Forensic Science • Explosives • Engineering • Questioned documents • Fingerprints • Pathology • DNA

23. The Murrah Building, Oklahoma City Domestic Terrorism

24. The Scenario--1995 • ANFO explosive and timer packed into a rented truck, which was then parked outside Murrah building • Explosive confined to closed space such as truck is much more powerful • Resulting explosion resulted in severe damage to building and loss of more than 100 lives

25. Goals of Investigation • Identify victims • Identify explosive • Find timer and bomb parts • Determine method of delivery

26. Evidence Sought • Easier to find than in WTC because bomb seat outside building • Explosive residues • Bomb parts • Bodies and body parts; cadaver dogs, flies • Personal effects; helps in identification of human remains

27. Areas of Forensic Science • Anthropology • DNA and serology • Pathology • Entomology • Explosives • Trace evidence • Engineering • Questioned documents • Fingerprints

28. WTC Destruction-2001

29. The Scenario • Large airplanes, loaded with fuel, crash into WTC buildings • Raging fires ignite everything in building above crash sites. • Metal supports melt from heat • Building collapses due to inability to support its own weight after structural damage • Thousands of people killed • http://www.history.com/topics/9-11-attacks 4min video

30. Goals of Investigation • Cause known, no need to determine how destruction occurred • Recover and identify bodies, parts of bodies and charred remains • Recover personal effects that might help identify victims or perpetrators • Evidence that might determine how hijackings occurred.

31. Evidence Sought • Bodies and body parts; cadaver dogs, flies • Charred remains • Personal effects • Trace evidence such as charred papers • Weapons such as knives • Constraining devices such as wire

32. Areas of Forensic Science • Anthropology • DNA and serology • Odontology • Pathology • Entomology • Trace evidence • Questioned documents • Fingerprints • Tools and toolmarks

33. Boston Bombing—April 15, 2013

34. Two pressure cooker bombs exploded during the Boston Marathon at 2:49 pm killing 3 people and injuring an estimated 264 others. The bombs exploded about 12 seconds and 210 yards (190 m) apart, near the finish line on Boylston Street

35. A pressure cooker bomb is an The IED was created by inserting explosive material into a pressure cooker and attaching a blasting cap into the cover of the cooker. • Pressure cooker bombs have been used in a number of attacks--- 2006 Mumbai train bombings, 2010 Stockholm bombing (failed to explode), 2010 Times Spare car bombing attempt (failed to explode)

37. Goals of Investigation • Cause known, no need to determine how destruction occurred • Recover and identify bodies, parts of bodies and charred remains • Recover personal effects that might help identify victims or perpetrators • Evidence that might determine how the object was left at the scene.

38. Evidence Sought • Photos of person of interest • Personal effects • Bomb parts; timer, casing, etc. • Explosive residue • Constraining devices such as pieces of the pressure cooker, wire or duct tape

39. Areas of Forensic Science • Anthropology • DNA and serology • Odontology • Pathology • Entomology • Trace evidence • Questioned documents • Fingerprints • Tools and toolmarks