1. Class Name, Instructor Name
Lasley & Guskos, Criminal Investigation: An Illustrated Case Study Approach 1ed
Chapter 17
ARSON AND EXPLOSIVE SCENES
Class Name, Instructor Name
Date, Semester

2. CHAPTER OBJECTIVES Summarize the trends and elements of arson
Summarize the motivations and characteristics of arsonists
Describe how arson investigations are conducted
Describe the investigation of bombings and bomb threats

3. Summarize the trends and elements of arson
Learning Objectives
After this lecture, you should be able to complete the following Learning Outcomes
Summarize the trends and elements of arson

4. Trends and Elements of Arson

5. Intentionally setting a fire for the purposes of destruction
Arson Defined
Intentionally setting a fire for the purposes of destruction
16% of arsons result in an arrest
2% of this number are convicted of arson
2 billion in property loss per year
More than 700 lives lost per year
Under most laws, the act of arson is considered complete merely by the presence of some sort of burning, regardless of how serious or slight the fire damage may be

6. Investigating Arson
Incendiary—intentionally set and legally defined as an arson
Natural—acts of nature
Accidental—defective appliances, cigarettes, chimney sparks, etc.
Undetermined—future investigations may determine the cause

7. Intentional

8. Fire Triangle-oxygen, fuel, heat
Incipient Stage (fuel present)
Smoldering Stage (smoke/gas emitted from fuel)
Flaming Stage (visible flame erupts from smoldering fuel)

9. Investigating the Burn Site
Point of Origin—outward in search method to determine where the fire began
Overhaul—moving burning articles from their original position to inspect for burning embers which could reignite
Multiple points of origin—erratic burn patterns, multiple points of ignition, offender wanted to ensure fire erupted
Accelerants—substances used to speed up the fire starting process

10. Indicators of Accelerant Use
“V” burn pattern are without accelerant, inverted “V” burn pattern is with accelerant
Puddling (darkening) shows that accelerants were used to pool in a particular area and it is burned more intensely
Streamers or Trailers
Wood, paper, rope that have been soaked in accelerant to increase combustibility

11. Indicators of Accelerant Use
Early smoke color
White or gray smoke
Alligatoring of Wood
Charring that produces large shiny blisters on the burn wood
Melted metals
Can estimate fire temperature based on the metal being melted

12. Situational Indicators of Arson
Target location
Target preparation
Ignition devices
Calling 911
Fire watching

13. Flashover-situation where entire room burns into flames causing total destruction
Flashover without accelerant signs
Burning on top surfaces of material
Lack of normal fire from point of origin
Lack of accelerant residue
Demarcation lines on walls and area

14. Signs of intentionally set vehicle fires
Missing parts or accessories
Personal items missing from the vehicle
Tool marks on broken or leaking sources of fuel (gas lines, gas tank, gas cap)
All windows completely rolled down or rolled down in abnormal patterns
Multiple points of origin, e.g., extensive concentrated burning in both the engine and passenger compartments
The hood is raised and the doors are opened
Containers, matches, hoses, or other means of accelerant use at the scene
Vehicle owner was present when the fire began and has burns or smells of smoke
Pour patterns on the vehicle showing the placement of accelerant
Downward or drip-down burning in areas such as the tires, the trunk, and passenger compartment where fuel sources are not present

15. Summarize the motivations and characteristics of arsonists
Learning Objectives
After this lecture, you should be able to complete the following Learning Outcomes
Summarize the motivations and characteristics of arsonists

16. Poor school performance
Arsonist Profile
Over half younger than 18
80% Caucasian
Prior offenses
Troubled family
Poor school performance

17. Common motives for arson
Revenge
Ex-employees, estranged lovers, feuding families, etc.
Vandalism
Typically set on school grounds, recreation fields, trash cans, etc.
Excitement
Thrill seeking pyromaniacs, psychological pleasure
Profit
Direct or indirect monetary gain
Extremist
Make statements about social, political, or religious issues or causes
Compulsive
Mass, spree, serial arson
Crime concealment
Concealing another crime

18. Extremist

19. Describe how arson investigations are conducted
Learning Objectives
After this lecture, you should be able to complete the following Learning Outcomes
Describe how arson investigations are conducted

20. Bomb & Explosions Investigations
Handled by: bomb disposal technicians forensic engineers military ordinance experts other specially trained personnel 3,500 explosive incidents per year Over 200 injuries Over 20 deaths

21. Mechanical Explosives
Occur when a vessel or container bursts as a result of internal pressure from expanding gases
BLEVE-boiling liquid expanding vapor explosion 21 21

22. Chemical Explosives
Caused by high-pressure gases produced by chemical reactions involving liquid or solid fuels
Usually involve explosive mixture of air and fuel derived from a petroleum product
Detonation & deflagration 22 22

23. Describe the investigation of bombings and bomb threats
Learning Objectives
After this lecture, you should be able to complete the following Learning Outcomes
Describe the investigation of bombings and bomb threats

24. Explosives and Bombs
Explosives are substances that produce explosions through chemical reactions
Explosives are referred to as bombs or IEDs
They are classified as high explosives or low explosives
High explosive produce a blast pressure wave, while low explosives use petroleum, gunpowder, black powder, or combustible agent.

25. Preblast Investigations and threat by phone & threat assessment
When is the bomb going to explode?
Where is the bomb right now?
What does the bomb look like?
What kind of bomb is it?
What will cause it to explode?
Did you place the explosives?
Why did you place the explosives?
What is the caller’s name and address?
Does the caller have an accent?
Are there any current international or national political, religious, or other activities going on that could be related to the threat?
Does the caller appear to have knowledge about bombs and their construction?
Does the caller seem nervous, angry, or confused?
Does the caller seem to be merely creating a hoax to disrupt some type of normal activity at the suspected bomb location?

26. Did caller have knowledge of device

27. Preliminary Assessment of the Explosion Scene
Blood sprayed by the explosion possibly containing bloodborne pathogens
Dangerous metal and glass debris
Ongoing fires or locations for potential fires
Poor structural integrity of structures
Damaged utilities: gas, water, electrical
Hazardous materials (HAZMAT) in air, water, soil, or within structures or vehicles
Potential for secondary explosions, either natural or mine-style traps
Dangerous persons such as snipers or suicide bombers

28. Postblast Investigations
Establish the perimeters- inner and out perimeters must be established
Determine the search method- engage in a focused search for specific pieces of physical evidence
Examine the epicenter- this can determine whether the blast was accidental or intentional

29. Postblast Investigations
Assess the type of explosion- analysis of epicenter and its immediate surroundings provide the type of explosion clues
Determine the search method- engage in a focused search for specific pieces of physical evidence
Determine the type of explosion-blast area can assess high or low explosives
Collect evidence- EXSPRAY or Dropex

30. Vehicle Bombings Accidental or intentional explosions
Location of the bomb can be located by the crater created by the explosion known as petaling
Bomb may have been placed in the vehicle intending to kill the occupants
Vehicle was used to transport explosive material and blast was unintentional
The vehicle was used as a car bomb

31. Accidental or Intentional

32. CHAPTER SUMMARY
In a general sense, arson can be defined as “any willing or malicious burning or attempt to burn, with or without intent to defraud, a dwelling house, public building, motor vehicle or aircraft, personal property of another.” Under most laws, the act of arson is considered complete merely by the presence of some sort of burning, regardless of how serious or slight
the fire damage may be.
Whether the fire is located outdoors or indoors, the investigation of a burn site should begin at the outermost locations of the fire-involved area and proceed inward. The primary goal of this “outward-in” search method is to identify the location(s) where the fire originated, known as the fire’s point of origin.

33. CHAPTER SUMMARY
Mechanical explosions usually occur when a vessel or container bursts as the result of internal pressure from expanding gases. A common form of these explosions, referred to as a BLEVE (Boiling Liquid Expanding Vapor Explosion), can happen with an object as small as a spray can or as large as an industrial petroleum holding tank. Chemical explosions occur as the result of high-pressure gasses produced by chemical reactions involving liquid or solid fuels. Explosives are substances that produce explosions through chemical reactions. They are referred to as a bomb or IED (Improvised Explosive Device) when used for illegal purposes.

34. CHAPTER SUMMARY
Most preblast investigations involve bomb threats. Most threats are made by a letter or telephone call, although threats are gaining popularity. The initial stages of investigation should evaluate all information available from all available witnesses, and in particular the person(s) receiving the threat. Before focusing on any other aspect of investigation, determine all safety or health hazards in and around the scene before entering the blast area. Enter and begin assessment of the scene at the outermost area of the explosion site. Determine the epicenter of the explosion by finding where the most damage has been done, often a tell-tale crater blown in the ground where the bomb was detonated. Gather materials that may have been used to construct and detonate the bomb.