Examining the Scene and Finding the Origin   Chapter 12
Objectives <ul><li>Describe what to look for on the exterior of the structure that would indicate the area of origin </li>...
Case Study <ul><li>There were evident burn patterns on the outside of a resort-type home </li></ul><ul><li>Working from th...
Introduction  <ul><li>You cannot find the cause of the fire until you have located the area of origin  </li></ul><ul><li>I...
The Assignment  <ul><li>There must be a comprehensive policy and procedure on how fires are to be investigated by the loca...
Systematic: A Process <ul><li>Approach must be systematic and consistent </li></ul><ul><ul><li>Must follow a logical path ...
Safety Issues <ul><li>Safety is the first and last concern </li></ul><ul><li>Structural stability  </li></ul><ul><ul><li>K...
Utility Hazards Figure 12-2 A noncontact detector that will activate in the presence of an electrical current.
Secure the Scene  <ul><li>Efforts should have been made to cordon off the area for the safety of the general public </li><...
Examining the Scene During Suppression Operations <ul><li>In an active burning fire, investigation is not a primary functi...
Examining the Scene During Suppression Operations <ul><li>For larger events, the investigator will be assigned and will re...
Examining the Scene During Suppression Operations (cont’d.) <ul><li>If the OIC feels that it is not safe for the investiga...
Exterior Examination Figure 12-3 Conflicting burn patterns on the exterior of the structure showing wind direction differe...
Building Systems <ul><li>Compartmentation is a component of the building system </li></ul><ul><li>Walls should have a fire...
Building Systems (cont’d.) <ul><li>Include the examination of utilities such as the heating, ventilation, and air conditio...
Interior Examination  <ul><li>Before entering the structure, the investigator must assess the safety of the structure  </l...
Debris Removal  Figure 12-4  Debris thrown out of the second-floor window, hampering a proper investigation of the fire sc...
Examining Contents <ul><li>Patterns on contents can be vital to the discovery of the area of origin  </li></ul><ul><ul><li...
The Area of Origin <ul><li>With careful examination of all burn patterns, the area of origin can be identified  </li></ul>...
Summary <ul><li>Safety has to be the first concern of everyone on the scene  </li></ul><ul><li>An accurate determination o...
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Chapter 12

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Chapter 12

  1. 1. Examining the Scene and Finding the Origin Chapter 12
  2. 2. Objectives <ul><li>Describe what to look for on the exterior of the structure that would indicate the area of origin </li></ul><ul><li>Describe what to look for when examining the interior of a structure </li></ul><ul><li>Describe the steps taken to do a fire scene reconstruction and the benefits obtained from such an effort </li></ul><ul><li>Describe events or conditions that may create greater char, skewing the path of fire travel </li></ul>
  3. 3. Case Study <ul><li>There were evident burn patterns on the outside of a resort-type home </li></ul><ul><li>Working from the least damaged area to the most damaged area was hard </li></ul><ul><li>The area of origin was floor level in the kitchen on the east wall </li></ul><ul><li>Interviews with the occupants divulged that when they left the house, they emptied the ashtray they had been using into the trash can </li></ul>
  4. 4. Introduction <ul><li>You cannot find the cause of the fire until you have located the area of origin </li></ul><ul><li>Investigators must work their way through the fire scene interpreting the burn patterns to find the area of origin </li></ul>
  5. 5. The Assignment <ul><li>There must be a comprehensive policy and procedure on how fires are to be investigated by the locality </li></ul><ul><li>The national fire incident reporting system (NFIRS) has an entire section on the origin and cause of the fire to be filled out by the fire officer in charge (OIC) </li></ul><ul><li>Fire investigator refers to the person who examines the scene </li></ul>
  6. 6. Systematic: A Process <ul><li>Approach must be systematic and consistent </li></ul><ul><ul><li>Must follow a logical path that is conducive to identifying the fire area of origin </li></ul></ul><ul><ul><li>Can prevent overlooking key indicators and evidence </li></ul></ul><ul><ul><li>A common approach is working from the least damaged area to the most damaged area </li></ul></ul><ul><ul><ul><li>Smoke patterns and burn patterns can be the path to the area of origin </li></ul></ul></ul>
  7. 7. Safety Issues <ul><li>Safety is the first and last concern </li></ul><ul><li>Structural stability </li></ul><ul><ul><li>Knowledge of proper building construction is essential </li></ul></ul><ul><ul><li>Heavy technical teams can help shore up structures </li></ul></ul><ul><ul><li>Sometimes damage may be so severe that the only recourse is to demolish structural elements </li></ul></ul><ul><ul><ul><li>Crane or other heavy equipment can be called in to lift damaged items away from the structure </li></ul></ul></ul>
  8. 8. Utility Hazards Figure 12-2 A noncontact detector that will activate in the presence of an electrical current.
  9. 9. Secure the Scene <ul><li>Efforts should have been made to cordon off the area for the safety of the general public </li></ul><ul><li>Security must be maintained throughout the investigation </li></ul><ul><ul><li>Monitor the exterior while the investigator is inside the structure </li></ul></ul>
  10. 10. Examining the Scene During Suppression Operations <ul><li>In an active burning fire, investigation is not a primary function of the suppression officer </li></ul><ul><ul><li>Engine company officer usually will not have the quality equipment or the opportunity to take photos of the scene </li></ul></ul><ul><ul><li>However, if there is time, the engineer or other personnel may be able to snap a few photos </li></ul></ul><ul><ul><ul><li>Camera can use a standard 35-mm film that requires processing, or the camera can be digital </li></ul></ul></ul>
  11. 11. Examining the Scene During Suppression Operations <ul><li>For larger events, the investigator will be assigned and will report to the OIC </li></ul><ul><li>Investigator may find it beneficial to go into the structure even before the fire has been completely extinguished </li></ul><ul><ul><li>Should only be done if the investigator is completely qualified to work in an imminent danger to life and health (IDLH) atmosphere and has proper equipment </li></ul></ul>
  12. 12. Examining the Scene During Suppression Operations (cont’d.) <ul><li>If the OIC feels that it is not safe for the investigator to enter, it is prudent for the investigator to comply </li></ul>
  13. 13. Exterior Examination Figure 12-3 Conflicting burn patterns on the exterior of the structure showing wind direction different for each opening.
  14. 14. Building Systems <ul><li>Compartmentation is a component of the building system </li></ul><ul><li>Walls should have a fire rating as in the use of sheetrock </li></ul><ul><li>Fire investigators must be familiar with: </li></ul><ul><ul><li>All forms of sprinkler systems </li></ul></ul><ul><ul><li>Fire-extinguishing foam or dry chemical extinguishing agent delivery systems </li></ul></ul><ul><ul><li>Total flooding systems such as CO 2 systems </li></ul></ul>
  15. 15. Building Systems (cont’d.) <ul><li>Include the examination of utilities such as the heating, ventilation, and air conditioning system </li></ul><ul><li>Key issue is the impact building systems had on the fire growth and the extension of the fire to other areas of the building </li></ul>
  16. 16. Interior Examination <ul><li>Before entering the structure, the investigator must assess the safety of the structure </li></ul><ul><li>Examine burn patterns to interpret the relative length of time the fire burned in each area </li></ul><ul><ul><li>Lowest burn is of importance because fires naturally burn upward and outward </li></ul></ul><ul><ul><li>Use tools such as the depth of char gauge on wood char and check calcination to help to determine the relative burn times </li></ul></ul>
  17. 17. Debris Removal Figure 12-4 Debris thrown out of the second-floor window, hampering a proper investigation of the fire scene.
  18. 18. Examining Contents <ul><li>Patterns on contents can be vital to the discovery of the area of origin </li></ul><ul><ul><li>Can support patterns on walls, ceilings, and floors </li></ul></ul><ul><ul><li>Can help resolve any confusing patterns in the structure </li></ul></ul><ul><li>Burn patterns on furnishings can show the direction of fire travel </li></ul>
  19. 19. The Area of Origin <ul><li>With careful examination of all burn patterns, the area of origin can be identified </li></ul><ul><li>A successful hypothesis can be tested only after a systematic search of the entire fire scene </li></ul><ul><ul><li>Any conflicting patterns must be taken into account </li></ul></ul>
  20. 20. Summary <ul><li>Safety has to be the first concern of everyone on the scene </li></ul><ul><li>An accurate determination of the area of origin of the fire is the first step in the final determination of the fire cause </li></ul><ul><li>With the application of a systematic search along with scientific methodology, the investigator can usually locate the area of origin </li></ul>

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