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

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

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

Trends and Elements of Arson

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

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

Intentional

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

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

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

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

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

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

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

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

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

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

Extremist

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

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

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

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

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

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.

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?

Did caller have knowledge of device

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

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

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

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

Accidental or Intentional

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.

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.

CHAPTER SUMMARY Most preblast investigations involve bomb threats. Most threats are made by a letter or telephone call, although e-mail 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.