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Investigating cases of arson is a tricky aspect of forensic science that needs systematic approach to arrive at the resolution. Poorly conducted investigation taints potential physical evidence and some evidence by witnesses might be overlooked. Importantly, it is important to investigate and get necessary data before theorizing about the cause of the fire; theorizing before facts leads to twist of facts to suit the theories. It is in cognizance of potential misgivings of some investigation processes that some organizations have established procedures for arson investigation. For example, the National Institute of Justice developed improved procedures for the collection of evidence and investigation of arson scenes (Samuels, Boyd & Rau, 2000). The paper is divided into three parts; the first part of the paper explains how the fire scene will be investigated. The second part of the paper explains the indicators and evidence at the scene on the possible cause of the fire. The part details the significance of the burn patterns and fire spread. The third part hypothesizes into the cause of the fire based on the evidences and indicators.
1. Conducting Investigation at the Fire Scene
As an investigator, before arriving at the fire scene the fire fighters had arrived and managed to extinguish the fire. The fire fighters adhered to the size-up factors and strategized on the effective strategies and tactics that could be used with the lowest level of risk. According to International Association of Fire Chiefs and National Fire Protection Association (2014), fire fighters always consider the possibility that lives could be in the burning structure; that is why rescue and search are done simultaneously as the fire is extinguished. The sizes up factors include the occupancy of the house in terms of the type of materials in the house. Consideration of the occupancy helps fire fighters to assess the level of risk to the occupants and the civilians. In addition, the fire fighters also considered the time in terms of the exact time and season of the year; time influences rescue and search operations. According to Gustin (2009), an incident of fire in a kitchen requires immediate search in the living rooms; the season determines the possible cause of fire for example, whether it is fire spreading from one building to another due to strong winds. In addition, some seasons in some areas are prone to hurricane; as such, fire fighters must be prepared to cut hurricane shutters. Furthermore, the fire fighters considered the available fire fighting resources and the size of the building; old buildings are relatively smaller than modern buildings. After the fire fighters had extinguished the fire, they established that there were no causalities or fatalities that arose from the fire. They also noted that electricity connection, mains gas and water supplies were safe and did not cause or contribute to the fire. It is therefore the duty of the investigator to determine the cause of the fire.
1.1 Arriving at the Scene
The first individuals to arrive at the scene are the first responders; in this regard, the first responders are the fire fighters and first witnesses. On arrival at the fire scene, a mental note of all that are at the scene including the conditions of the scene, the people around the scene and any other unusual activities at the scene are noted. In addition, the nature of the structure in terms of whether it is a residential or a commercial structure and the nature of the occupancy will be noted. Furthermore, the time of arrival and the prevailing weather condition will be mentally noted.
1.1.1 Observing the Fire and Scene Conditions
After cordoning the scene, an assessment of the scene in terms of structural collapse and any other hazard is done. During the observation of the scene, the surrounding conditions of the scene; for example, unusual odors, fire trailers and presence of containers and exterior charring on the building are captured (National Institute of Justice, 2009). During the observation, notes about the condition of the scene, video images and pictures of the scene are taken. In addition, the information about the scene safety is communicated to other colleagues.
1.1.2 Exercise Scene Safety
Exercising scene safety is the prerogative of the first responders. Personal safety and the safety of public are paramount. Some fire scenes may be designed to harm responders; as a result, it is important that first responders put on personal protective equipment. As part of exercising scene safety, the evaluation of the structure in terms of its susceptibility to collapse, chemical, biological and electrical risks are assessed. For example, chemical risks will be superficially assessed by sense of smell or checking for any liquids, smoke or solid materials around the scene. In case of identification of a queer device, solid or odor, then specialized personnel trained on removal of dangerous equipment will be called and requested to remove them from the scene (National Institute of Justice, 2009). The surrounding of the structure will be evaluated and safety zones established.
1.1.3 Preserving the Fire Scene
The process of extinguishing fire and rescuing individuals may contribute to loss of some physical evidence. For instance, during search and rescue operations, fire fighters and other first responders may break some windows or change fire patterns. In addition, the movement of fire fighters may leave shoe prints or introduce liquids that damage evidence. It is necessary that the available evidence is protected from further destruction (National Institute of Justice, 2009). Meanwhile, detailed observation of the scene is done and mentally noted. However, due to the gravity of the details some information is documented using pictures; for example, the fire patterns, presence of fire trailers such as ignitable liquids and piles of newspaper are pictured. In addition, tire impressions and shoe prints, existence of broken windows and doors, the distribution of debris, location of containers and indications of forced entry such as tool marks and tools are pictured. Trace evidence such as existence of body fluids, blood, fingerprints and hairs are pictured in relation to their location. Importantly, a part from documenting the evidence by taking images, needless destruction of the structure is avoided. Some transient evidence such as hair will be covered with clean boxes and other evidence will be identified by markers and cones (National Institute of Justice, 2009). Some evidence that might be destroyed when the structure collapses should be removed after taking its picture in its original location.
1.1.4 Establishing Security and Control
Controlling the scene is necessary for purposes of avoiding destruction of evidence. It is important to cordon off the scene from the public using fire line tape. A cordon help in protecting the scene, prevent unauthorized accesses and interference to the scene and ensures the integrity of the scene is maintained during the period of investigation (Geisler, 2016).
1.1.5 Coordinate Interagency Activities
Investigating a fire outbreak requires effective coordination between different parties; they include the fire fighters, representatives of utility companies such as electricity, water and gas suppliers, law enforcement officers and the public among others (National Institute of Justice, 2009). The involvement of the parties must be well coordinated to avoid conflict and duplication of roles. A command post within one of the safety zones will be established. In addition, the staging areas to ensure smooth flow of support vehicles will be established. The command post will be used to communicate to other authorities on the status of the incident, witness, injuries and other necessary facts.
1.2 Evaluating the Scene
As an investigator, I arrived at the scene after the fire fighter had extinguished the fire; as such, I am not the first responder. In addition, it is necessary to address all the legal conditions for scene search and collection of evidence. During scene evaluation, i will determine the necessary witnesses and carry out a survey on what must be done at the scene; importantly, I will establish investigator’s presence (National Institute of Justice, 2009). Among the witnesses that will be contacted are the first responders, who were the fire fighters
1.2.1 Contacting First Responders and Establishing Presence
As an investigator, I will take full control as the lead investigator by contacting the first responders who are the fire fighters. The contact will help to assess current and previous events about the status of the fire scene. Importantly the contact will help in identifying the key personnel that will help in the investigation. That means that the level of assistance from other parties will be determined and the identification of the personnel at the scene done (National Institute of Justice, 2009). The safety of the scene for all the necessary personnel will be assessed through discussions with the first responders and personal observations.
1.2.2 Defining the Scene’s Boundaries
The scene perimeter will be established after determining the area on the site where the examination will be done. During the examination of the site, scene assessment on the extent of the damage will be done by moving from the area of least damage to the area of most damage. In this scene, movement will be from PPT 3 which is the front of the house, to PPT 4 which is the back part of the house, and then to PPT 6 which is the charred window and then to PPT 7, 8, 9, 10,11 and 12 sequentially. Non fire evidence such as image on PPT 5 will be captured. After establishing the scene boundary the procedures for controlling access to the scene will be established.
1.2.3 Indentifying and interviewing Witnesses
As the investigator, I will contact the first responder, who in this case is the fire fighters to document their observations and any picture and video images that they might have about the scene (National Institute of Justice, 2009). In addition, the first responders may help in identifying other witnesses. I will also identifying the owner or the occupant of the house and conduct an interview on what might have ensued.
1.2.4 Assess Scene Security at the Time of the Fire.
The investigator should assess and determine the state of the structure’s security; for instance, whether the fire detection, ventilation conditions or if there were any evidence of vandalism. During the assessment, the investigator will ask the first responder where there entry was, whether any systems in the house were activated. The investigator will also document the condition of the windows and doors. The information about the scene security helps in identifying the origin and spread of the fire (National Institute of Justice, 2009).
1.2.5 Identifying the Resources Needed for Processing the Scene
As an investigator, I recognize my investigative limitations based on my expertise; consequently, I will identify the other personnel that will help in the investigation. For instance, identifying the source and spread of the fire requires specialized training and experience that I lack. As such, I will request for specialized personnel; furthermore, equipments such as marker cones, lights, gloves, evidence bags, decontamination equipment, barrier tape and tape measures will be required.
1.3 Documenting the Scene
After evaluating the scene, the scene is documented using tools such as cameras. The scene is also described with supportive information from witnesses, photos and investigators opinions.
1.3.1 Photographic Documentation
Photographs create permanent records of the scene; they also support written information collected from witnesses, personal opinion by giving the graphic description of the scene. The scene should be photographed before any disturbance or removal of the evidence (National Institute of Justice, 2009). Photos should include any assembled crowd, the fire in progress, the exterior and the interior parts of the fire scene and any physical reconstruction of the scene.
1.3.2 Describing and Documenting the Scene
All the information collected from the first responders, witnesses and other agencies such as utility personnel will be compiled in a narrative written description format. The written description recreates the scene for scientific analysis and judicial purposes. The description should correlate and support the photographs taken. The written description can also include sketches to give accurate representation of the scene including its dimensions and other important features.
1.4 Processing Evidence at the Scene
After describing and taking the photos of the scene, other collectable evidence should be assembled, preserved and stored.
1.4.1 Identification, collection and Preservation of Evidence
The evidence will be collected after identifying and documenting them. The collected evidence is then preserved for further analysis in the laboratory. During the collection of the evidence, it will not be contaminated. All the evidence will be accompanied with written notes and placed in labeled containers for transportation. Importantly, the packaging of the evidence will adhere to the laboratory policies; for example, when the evidence is flammable, it will be labeled as such.
1.4.2 Preventing Evidence Contamination
Prevention of evidence contamination is a continuous process that started with the first responders and then carried on by the investigator during the definition of the scene boundary. To avoid contamination, protective gear will be worn; tools for collecting the evidence will be clean and access to the scene will strictly be controlled; furthermore, all packages will be sealed (National Institute of Justice, 2009).
1.4.3 Packaging and Transporting Evidence
The collected material will be packaged to prevent their destruction and transported to the laboratory for further analysis or for presentation to the court of law. Transportation will adhere to transport rules and caution will be taken to prevent contamination.
1.4.4 Establishing and Maintaining the Chain of Custody
When the investigator maintains the chain of custody of the collected evidence, it verifies the integrity of the evidence. The chain of custody is established by documenting the sample number, date of collection, collectors’ name and location where it was found and the necessary description of the evidence (National Institute of Justice, 2009). During transfer from custody to another, the date of transfer, the manner of transfer and the recipient’s name will be documented.
1.5 Completing the Scene Investigation
After identifying, collecting and removing all evidence and all physical characteristics of the scene have been documented, the investigator will ensure that health and safety issues are communicated to the party receiving the scene.
1.5.1 Release the Scene
Releasing the scene is done after all evidence is in custody, a discussion on the preliminary scene finding have been done with the team members and post scene issues such as interview results, insurance inquiries have been sorted out. In addition, all investigative equipment will be removed from the site. The date of release, the authority releasing the scene, the recipient of the site and the conditions of the scene at the time of release will be documented.
1.5.2 Submitting the Report to the Appropriate Database
The final report will be written and submitted to the relevant agencies to help in profiling fire trends
2 Fire Indicators and Evidence
A fire pattern is defined as the measurable or visible physical effects that remain after a fire; it represents the history of the fire (Hine, 2004). Fire usually burn at the point of origin or near the point of origin longer than in adjacent places; as a result, all factors being equal, most destruction should be at the point of origin. The patterns observed include lines of demarcation, which delineate regions affected by heat and smoke from those that are not affected as seen in PPT 8 and 9. The lines of demarcation show whether the window or door was open. Based on PPT 8 and PPT 9, the line of demarcation show the upper parts of the shelves to have be more affected than the lower part indicating that the window was open and the door was closed. Furthermore, the doors to the kitchen cabinets are made of metal; as such, the line of demarcation exhibits patterns relative to the thermal exposure. Based on PPT 8 and PPT 9, the line of demarcation is due high thermal exposure on the upper part of the cabinet doors indicating extensive thermal heating on the upper part.
Charring is a fire indicator that shows the intensity, spread and intensity of the fire. Different materials have different moisture content; therefore, charring may not be reliable in determining the intensity and duration of exposure to fire. Relatively, a comparing of charring depths in different locations can determine the relative time of exposure.
The objective of the fire scene examination of to identify the source of the ignition or the first fuels that ignited in the fire. Hine (2004) notes that whereas a match is an ignition source, it is unlikely to ignite a solid metal bar but can ignite a piece of newspaper. Effective identification of the source of the fire starts by examining the exterior part of the house and documenting the evidence. There are two accesses to the house, the front door picture in PPT 3 and the hind door pictured in PPT 7. The main access to the house is the hind door due to presence of external seats and pictured in PPT 4. Next to the hind door is a window; one can see through the house from the back to the front through the window due to presence of another window in the front part of the part as indicated in pictures on PPT 3 and PPT 4. The upper outside part of hind door is tainted with smoke; indicating that the fire must have started in the area right behind the door. Notably, gases such as smoke from combustion will flow towards paths of least resistance around obstructions and in an upward manner (Daeid, N N, 2005). The front part of the house has two windows; one of the windows is partially charred on its upper part. The fire seemed to have damaged the hind part of the house compared to the front part as seen in PPT 3 and 4. The damage to the exterior part of the house limited to the openings, which are the windows; however, most damage is in the interior parts of the house. The level of destruction indicates that the fire may have started in one of the rooms in the hind part of the house. The hind parts contain the kitchen; it also includes an extension of the living room as seen in PPT 8, 9 and 10. Comparing the level of damage in the living close to the front window and by looking at the dormer window above living room, it indicates that the front part of the living room was not severely burned. In addition, the roof part in the hind part of the living room was not as damaged as the roof part above the kitchen. Therefore, the fire may have started in the hind part of the house in the kitchen.
Fires develop in four distinctive stages, which are; ignition, smoldering, health build-up and lastly rapid fire spread. Fairgrieves (2008) note that three ingredients must be available for the fire to start, namely, a fuel , the oxidant, which in is oxygen and energy in form of heat. Liquids and solid materials do not combust but produces enough heat that cause the burn in the process of pyrolysis.
Ignition occurs when all the ingredients to start a fire are available, which are oxygen, enough heat energy and a fuel. The minimum amount of heat energy needed to ignite fire depends on the fuel and is termed as the flash point (Fairgrieves, S. I 2008). When the fuel is exposed to oxygen and the flash point is reached, the fire starts. Upon ignition, the heat from the fire source was conducted by radiation, convection and conduction; it caused the adjacent areas close to the source of fire to heat up to an appropriate temperature that caused the fire to ignite. As identified above in the fire pattern, the fire must have started in the kitchen; either the owner of the house had left some food heating or a person ignited it in the kitchen. The ignition must have been on the upper parts of the kitchen shelves whose upper parts were more burned that the lower parts as shown in PPT 8 and 9. In addition, the upper parts of the kitchen shelves were exposed to air more than the lower parts. During combustion, the surrounding air increases in temperature and becomes less dense; hence, convectional currents maintain the less dense air on sustaining the burn on the upper part of the shelves (Rachel, D. V 2013). Notably, flames are conical; as such, a flame that burns a vertical plane leaves a conical-shape or V-pattern (Leihnacher, D 2016). In this regard, there are no V-patterns on the walls indicating that the fire ignited from the top and not bottom.
As the heat from the fire spread by radiation, conduction and convection; and as ventilation conditions changed, the smoke from the source had to follow the path with the least resistance, it spread upwards in the upper compartments and towards the doors further spreading the heat to those areas. As the heat spread to the upper areas, it did not smolder instead it produced flames that combusted the upper parts of the house. Smoldering is a flameless combustion which is characterized by localized burning.
The accumulation of heat in the kitchen and in the areas close to it caused hot gases from the ignition site to accumulate in the surrounding area. The presence of windows and door provided the necessary supply of air that sustained the combustion in the kitchen and the surrounding area longer than necessary. As the heat accumulated in the kitchen and the surrounding area, roof parts were also heating up. The heat buildup in the kitchen caused the flames to spread out in the upper shelves, some flames spread to the lower parts of the shelves and towards the hind door charring part of it as seen in PPT 7.
Rapid Fire Spread
The rapid fire spread occurred when the fire caught combustible material in the upper parts of the kitchen and started burning the roof. There was spontaneous combustion due to exothermic chemicals occurring with the materials and released heat as seen in PPT 10 (Daeid, N N, 2005). The fire spread to the living room next to the kitchen where it burned furniture on the floor. The upper parts of the living room were not severely damaged as seen in PPT 3 and 4. The fire spread to the front part of the living room and started burning the part of the roof covering the front part of the living room. It then started spreading to upper part of the front door and the other window as indicated in PPT 1. The fire may have spread from the kitchen to the living room due to presence on the window and the large hind door which enables easy circulation of air. The firefighters extinguished the fire before it damaged the whole house.
3 Hypothesis on the Possible Cause of the Fire
Based on the evidence on the fire patterns and the information gathered from the fire fighters and other investigations done by utility personnel; it is hypothesized that the fire might have been started by an arsonist who ran away. The investigations from the utility personnel from the mains gas, water and electricity supplier noted that mains gas, water and electricity supplies were safe and did not contribute to the fire. There are no evidences of other possible causes of the fire such as animals, open fires, radiant heat source, sun refracted light, explosion and chimneys and candles.
All fires tend to burn upwards, establishing the point of origin was determined by assessing the area that had the most burn, which indicated that the fire burned for a longer time at that point. In this regard, the seat of the fire was not at a lower point but rather at a higher point indicating some presence of a fuel source at a higher point, which in this case was in the kitchen. In addition, smoke deposits were more on the upper part of the hind door than any other point indicating the origin of fire as being near the hind door.
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