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FIR 4315, Fire Investigation Technician 1

Course Learning Outcomes for Unit IV Upon completion of this unit, students should be able to:

6. Determine the causes of fires. 6.1 Discuss the causes of incendiary fires with accidental fires.

7. Explain the use of incendiary devices, explosives, and bombs.

7.1 Identify the most common types of incendiary devices, explosives, and bombs.

Course/Unit Learning Outcomes

Learning Activity

6.1

Unit Lesson Chapter 21, pp. 338–356 Chapter 22, pp. 358–370 Article: “Investigation Findings and Lessons Learned in the West Fertilizer

Explosion” Unit IV Case Study

7.1

Unit Lesson Chapter 21, pp. 338–356 Chapter 22, pp. 358–370 Article: “Investigation Findings and Lessons Learned in the West Fertilizer

Explosion” Unit IV Case Study

Required Unit Resources Chapter 21: Explosions, pp. 338–356 Chapter 22: Incendiary Fires, pp. 358–370 In order to access the following resource, click the link below. Davis, S., DeBold, T., & Marsegan, C. (2017). Investigation findings and lessons learned in the West Fertilizer

explosion. Journal of Fire Sciences, 35(5), 379–395. https://journals-sagepub- com.libraryresources.columbiasouthern.edu/doi/pdf/10.1177/0734904117715649

Unit Lesson

Introduction All fire investigators need to be prepared to investigate an explosion at some point in their careers. The explosions that may be encountered are mechanical or chemical in nature most of the time. The damage caused by an explosion will be designated as low order or high order damage. The effects that surround explosions are the blast overpressure, wave effect, projected fragment effect, heat damage or thermal effect, and blast wave effect. There are many other factors that create the cause and effect of an explosion that will be covered in this unit. The second half of this unit is about incendiary fires. Incendiary fires are intentional fires that are ignited in a place and at a time when there should not be a fire. When looking at these types of fires, we need to understand the concept of multiple fires, trailers, unexpected ignition source or fuel load, or incendiary devices.

UNIT IV STUDY GUIDE Incendiary Devices, Explosives, Bombs

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Explosions When investigating the scene of an explosion, the techniques of fire investigation will be utilized. The explosion still has an ignition source and first fuel; all of the other pieces of the puzzle will combine together to help determine what happened. The requirements of a systematic approach to the investigation are required since the possibility of a crime is higher in an explosion. The systematic approach provides the investigator with a detailed analysis of the scene that will help him or her find and analyze all of the evidence, no matter how small. While most of the time, the scene of the fire will be confined to one building, the explosion scene will most likely be much larger. The systematic approach that the investigator has developed will assist in securing and maintaining the integrity of the scene. A firm grasp on scene safety is also important in the explosion investigation.

The types of explosions that fire investigators are most likely going to encounter are mechanical and chemical explosions. The most common mechanical explosion is the boiling liquid expanding vapor explosion or BLEVE. This type of explosion is seen when a propane tank fails and explodes. The job of the fire investigator is to figure out what happened and why it happened at this point in time. Understanding the scene while making sure it is safe needs to be a focus of the investigation, not only with a BLEVE but with all explosion investigations. This is all done while focusing on the requirements that are found in NFPA 921. A chemical explosion occurs when the combustion of a fuel is changed through a chemical reaction. This can occur in a number of ways and needs to be considered when looking at the cause and origin of the explosion. Electrical explosions are caused when the arcing of electricity produces enough heat to cause the explosion. Nuclear explosions are caused by the fission or fusion of atoms. NFPA 921 does not cover electrical or nuclear explosions (International Association of Fire Chiefs [IAFC], International Association of Arson Investigators [IAAI], & National Fire Protection Association [NFPA], 2019). The further analysis of an explosion considers whether the explosion caused low-order or high-order damage. Low-order damage is produced by the slow rise of pressure, and high-order results from the rapid rise of pressure. The low-order will also have most of the evidence right at the scene; high-order will have evidence

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thrown for hundreds of feet (Pape, Mniszewski, & Longinow, 2010). The blast overpressure and the effects that the blast wave has on the scene are the next issues the investigator has to consider. The quick outward pressure that comes from the origin of the blast will be stronger than the negative pressure wave that returns towards the origin. As a result of all of the air being displaced by the blast, the negative pressure behind the blast pulls air back in to balance the air pressure. The investigator needs to keep in mind that the negative pressure pulling air back to the point of origin can move physical evidence, possibly covering up the point of origin. In addition to the blast wave damage, the investigator needs to be cognizant of the ignition of combustible materials and the seismic effect of the shock wave. The scene analysis will continue by determining whether the explosion was seated in a particular place or was non-seated with the fuel flowing through the area; this will help with finding the point of origin of the explosion. What type of explosion occurred? What was the fuel of that particular explosion? Following all of the evidence back to the point of origin and determining the ignition source for the explosion allows the investigator to understand what happened with this particular explosion.

Incendiary Fires When the investigator is looking at an incendiary fire, he or she needs to remember that the scientific method must be followed and that the fire should be investigated in the same manner as all other investigations. An incendiary fire is a fire that occurs in a place and at a time when there should not be ignition sources available. Understanding some of the known indicators for incendiary fires will help the investigator with the analysis against the hypothesis for the fire that is under investigation. Signs of arson can be lit fires that spread quicker than accidental fires, fires on multiple floors, and patterns on the floor of the fire room. These also could be signs of heat-release rate being high in fuel, balloon frame construction, and flashover. The investigator needs to approach each fire with the systematic method no matter what he or she is told prior to the investigation. The first key indicator for an incendiary fire would be the observation of multiple fires in the same structure with no obvious way for the fire to spread to each location. A conversation with the first due company will allow the investigator to get an explanation of where the fires were found and what made them stand out from a regular fire. Overhaul and suppression activities should not disturb the evidence in the case, and proper analysis of the scene is needed to determine why there were multiple fires. There also needs to be a search conducted for signs of trailers connecting the multiple fires. Trailers are items used to assist in spreading the

fire from one part of the structure to other areas. While trailers can leave obvious patterns on the floor, the investigator needs to be able to eliminate all other causes of the patterns that are found on the floor. The next part of the analysis in the incendiary fire is looking at the basic elements of fire: fuel and ignition. When analyzing a fire, the investigator must determine if the fuel load that was present and burned is appropriate for the environment where the fire occurred. Was there a large amount of paper products in the living room of a single-family home? Is this what would be expected in this area of a house? These are the questions

that need to be asked. Determining the ignition source and why it was there and able to cause the fire would be an obvious next step. While evaluating the ignition source, the investigator should be looking for signs of any obvious accelerants or evidence of an incendiary device that could have been used to start the fire. If the investigator feels it is necessary, an accelerant dog can be brought in to verify the presence of suspected

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accelerants. Remember, the conclusion and final verification has to come from the lab that analyzes the evidence. The next area of observation should be the structure where the fire occurred. The entry into the building should be checked to see if any forced entry happened prior to the arrival of the fire department. The point of origin of the incendiary fire is usually in an area of the building that is remote and less likely to be discovered by a passerby. If the seat of the fire is found to be near an appliance or some type of service equipment, the arsonist may be trying to cover up the cause of the fire by making it look like an appliance fire. The investigator should look for personal or business property that is not replaceable. If it is missing, this should be documented, and the owner should be asked about it. The investigator should check all fire protection and suppression systems and should determine if these were tampered with prior to the fire department arriving. The fire investigator will also need to establish if the doors and windows were opened prior to the fire department arriving. If the windows were opened, this would have allowed air in, which would have fed the fire and caused it to spread faster. The National Center for the Analysis of Violent Crimes has identified six potential characterizations of fire scene behavior (IAFC et al., 2019). They include vandalism, excitement, revenge, crime concealment, profit, and extremism.

• Vandalism: The malicious fire setting that results in the damage of property.

• Excitement: This includes a number of categories including thrill-seeking, attention-seeking, recognition, and sexual gratification.

• Revenge: The perpetrator feels that he or she has wrongly received unjust treatment from someone. These fires can come in the form of retaliation against someone or personal property.

• Crime concealment: The act of arson is secondary to collateral criminal activity. The fire is used to conceal a crime.

• Profit fires: These fires are typically initiated for material or monetary gain.

• Extremism: This is one of the most dangerous motives that can play out in the political, social, and religious acts of crime. Terrorism, riots, and civil disturbances are found within this category.

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Conclusion The fire investigator should always use their situational awareness skills in observing conditions within the structure. The fire investigator should take note of the remaining debris utilizing sketches, drawings, and photographs of the fire scene. The systematic approach to explosive and incendiary investigations should always be followed, just like all other investigations.

References International Association of Fire Chiefs, International Association of Arson Investigators, & National Fire

Protection Association. (2019). Fire investigator: Principles and practice to NFPA 921 and 1033 (5th ed.). Jones & Bartlett.

Pape, R., Mniszewski, K. R., & Longinow, A. (2010). Explosion phenomena and effects of explosions on

structures. I: Phenomena and effects. Practice Periodical on Structural Design and Construction, 15(2), 135–140.

Suggested Unit Resources In order to access the following resources, click the links below. These three articles are a series on the effects of explosions on the structural integrity of buildings. Pape, R., Mniszewski, K. R., & Longinow, A. (2010). Explosion phenomena and effects of explosions on

structures. I: Phenomena and effects. Practice Periodical on Structural Design and Construction, 15(2), 135–140. https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=bcr&AN=49193785&site=ehost-live&scope=site

Pape, R., Mniszewski, K. R., & Longinow, A. (2010). Explosion phenomena and effects of explosions on

structures. II: Methods of analysis (explosion effects). Practice Periodical on Structural Design and Construction, 15(2), 141–152. https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=bcr&AN=49193784&site=ehost-live&scope=site

Pape, R., Mniszewski, K. R., Longinow, A., & Kenner, M. (2010). Explosion phenomena and effects of

explosions on structures. III: Methods of analysis (explosion damage to structures) and example cases. Practice Periodical on Structural Design and Construction,15(2), 153–169. https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=bcr&AN=49193788&site=ehost-live&scope=site

Learning Activities (Nongraded) Nongraded Learning Activities are provided to aid students in their course of study. You do not have to submit them. If you have questions, contact your instructor for further guidance and information. This is an opportunity for you to express your thoughts about the material you are studying by writing about it. Conceptual thinking is a great way to study because it gives you a chance to process what you have learned and increases your ability to remember it. Before completing your graded work, consider completing the “Case Study” and “On Scene” exercises for Chapters 21 and 22. Completing these exercises will help you with your graded work.

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The exercises can be found on the following page numbers: Chapter 21: “Case Study,” p. 338 Chapter 21: “On Scene,” p. 356 Chapter 22: “Case Study,” p. 358 Chapter 22: “On Scene,” p. 370 If you have any questions or do not understand a concept, contact your professor for clarification.