A Guide to Arson Investigation

1. A Guide to Arson Investigation 1

2. What is Arson? ARSON is the crime of burning property - the burning of a building or other property for a criminal or malicious reason. 2

3. The Chemistry of Fire The Fire Tetrahedron • The “triangle” illustrates the rule that in order to ignite and burn, a fire requires three elements — heat, fuel, and oxygen. • A fire is caused by the convergence of FUEL, O2, HEAT, & an uninhibited chemical chain rxn. 3

4. The Chemistry of Fire • A liquid burns when the temperature is high enough to vaporize it (flash point), while a solid must be hot enough to decompose into gaseous products (pyrolysis). • Glowing combustion or smoldering is burning at the fuel-air interface, such as a cigarette. • Spontaneous combustion, which is rare, is the result of a natural heat-producing process in poorly ventilated containers or areas. 4

5. Combustion • Fire is a combustion process during which oxygen (min. req. is 15%) is united with some fuel to produce noticeable quantities of heat and light (flame) and releases Carbon or CO, carbon monixde, a toxic gas, and water vapor. 5

6. Endothermic vs. Exothermic: 6

7. Fuels Flames Oxygen Heat • Combustion or burningis a complex sequence of exothermic (gives off heat or light) chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. 7

8. Heat Production: • Chemically, through rapid oxidation • Mechanically, as the result of friction • Electrically, due to an electrical malfunction • Kinetically, in a compressed gas because molecular activity is great increased • Nuclearly, through the splitting of atomic particles. 8

9. Transference Of Heat • Conduction – direct contact • Convection – super heated gases • Radiation – invisible waves that travel at the same speed as visible light. Radiant heat travel in a direct line from the source until it strikes the object. 9

10. Fires expand horizontally & vertically from the point of origin • They follow the path of least resistance – through ceilings, doorways, windows, stairways & other openings • Fires start when the minimum temperature needed to spontaneously ignite fuel, (ignition temperature), is reached. • The heat evolved when a substance burns-heat of combustion. 10

11. Stages of A Fire; Grow & Spread in 4 Stages: • Incipient Stage-Earliest stage. Duration may be a fraction of a second to hours, depending on the fuel available & ignition source • Emergent Stage-Combustion activity increases • Free Burning-The intensity of the fire increases. The intensity of the heat doubles with each 18°F temperature rise. • Oxygen-Regulated Smoldering-O2 enriched air in an area or room is depleted causing combustion to cease. Temp may exceed 1000°F. If O2 is re-introduced to the fire, a backdraft (explosive ignition) may occur. 11

12. STANDARD OPERATING PROCEDURES 12

13. Searching the Fire Scene • Origin and Cause Determination • Patterns – How does fire burn? Ignitable Liquids • “Sniffers” – Portable vapor detectors • Make Determination- Accidental vs. Incendiary 13

14. Searching the Fire Scene The causes of fire- 4 categories: • Natural (e.g., lightning) • Accidental (e.g., unintentional or negligent, but explainable human action) • Incendiary (e.g., intentional) • Undetermined (unknown) 14

15. Looking for Origin and Cause Origin and Causes • Windows blown away from structure • Evidence of forced entry • Missing inventory (warehouses, etc.) • Missing personal items such as photos, bibles, yearbooks, weapons, jewelry (homes) • Evidence of a previous fire • Unkempt yard "For sale" signs • Fuel cans • Fire extending beyond the perimeter of the structure 15

16. Origin and Cause (continued) • Large amount of damage • Low burning • Unidentifiable point of origin • No "V" burn patterns present • Lack of accidental causes • Separate and unconnected fires • Unusual burn patterns and high heat stress continue 16

17. Origin and Cause (continued) Be aware of fire movement • Fire generally move upward • Origin located closest to lowest point of most intense burning • Drafts & winds • Secondary fires • Stairways, holes, elevator shafts • Flammable liquids flow down 17

18. “V” patterns 18

19. COLLECTION &PRESERVATION Of Arson Evidence 19

20. Tools of the Trade • Metal cans and glass bottles Used containers must be keptsealed Only 1/2 to 2/3 of the containers are filled, to allow material sufficient air to breathe 20

21. Tools and Equipment Protective clothing • Safety and common sense are important • Tools: shovels, rakes, hoes, brooms, sifting screen 21

22. FirsT responders are crucial to preservation of evidence First responders need to recognize items that may have evidentiary value. To any subsequent investigations and take preventative measures to ensure Evidence is not damaged in the fire or rescuing process Protection of the Scene • The area around the scene needs to be secluded, not only for security reasons, but for protection of evidence 22

23. Scene Investigation Fire scenes are considered the hardest of any investigations because evidence is always destroyed. 2-3 Quarts of ash and soot debris must be collected at the point of origin of a fire in any arson case 23

24. Chain of Custody • The person who collects and processes the evidence is to take all responsibility for handling of the evidence • Proper records and files must be kept of who and where has handled the evidence • Mostly all evidence in arson investigations are subject to analysis • Preserving the evidence so that it is court admissible is one of the most important tasks 24

25. FIRE INVESTIGATION 25

26. Fire investigation is one of the most difficult of the forensic sciencesto practice. • In most forensic disciplines, even the basic question of whether a crime has been committed is normally obvious. 26

27. Origin and Cause of Investigation • After firefighters extinguish a fire, an investigation is launched to determine the origin and cause of the fire or explosion. Investigations of such incidents are done using a systematic approach and knowledge of basic fire science. 27

28. During a fire investigation, an entire process must be undertaken just to determine if the case involves arson or not. The difficulty of determining whether an arson fire has occurred or not arises because fires destroy evidence. 28

29. Fires can be caused by or involve most things people see or use. For this reason, fire investigators need to know not only basic science of fire behavior, but knowledge of many different areas of study (including construction, electricity, human behavior, vehicles etc) is helpful. 29

30. Categories of fires Accidental Fire Cause Natural Fire Cause Incendiary Fire Cause Undetermined Fire Cause 30

31. Accidental 31

32. Accidental 32

33. Accidental 33

34. Accidental 34

35. A C C I D E N T A l 35

36. Incendiary 36

37. Incendiary 37

38. Incendiary 38

39. Incendiary 39

40. Types of Arsonists • Revenge – 14% • Vandalism - 60% • Crime Concealment - 7% • Insurance Claims - 16% • Excitement & Pyromaniacs - 3% 40

41. Types of Arsonists 41

42. Church Arson • The leading cause of church fires is arson • Motives of the 100 people arrested in those fires included racial hatred, but juvenile vandalism, insurance fraud and thrill-seeking were also factors. • Churches are also targets because they are unoccupied at night and for long periods of time during the day. 42

43. Revenge • Result of arguments, hatred or jealousy • Victims are usually family, friends or other familiar people • Hate groups may not know victims • Often intoxicated at the time of their offense • Typically use matches and gasoline • Easily detected because they do not cover their tracks 43

44. Vandalism • Destroy property for fun or sport • Sometimes revenge is motivation • Usually have one or more accomplice • Half of all arson arrests are white males under age 18 • Tend to set fires at night 44

45. Crime Concealment • Usually burglary, often murder • Use fire to cover traces of the original crime or the criminal • Often set at night 45

46. Insurance Claims • Arson for Profit • Arsonist needs money, so they will set fire to their own property to collect on the insurance • “Fire Strippers” who set fires and then search the burned remains for plumbing, electrical and other construction materials • Usually do not set fire to property that has people in it • Generally, fires are set in the day time 46

47. Excitement • Set fires because they are entertained • Some like the sight of fire burning • Others enjoy watching the firefighters using their equipment • Usually intoxicated at the time of the fire • Do not set fire to inhabited property 47

48. Pyromaniacs • “Pathological Fire setters” • They get a sensual satisfaction watching fire destroy 48

49. Arson & Violence • Fires set intentionally can also go hand in hand with violence • Mob violence fires • Occurs where the median income is below the poverty line • Fire-setters have the least to lose in personal property 49

50. Little known Facts: Did you know that? • Arson is the #1 crime committed by juveniles. • 1/3 of all children killed by fire set the fire themselves. • Left untreated 81% of fire setters will repeat their dangerous actions. 50