1. Essentials of Fire Fighting
6th Edition
Firefighter I
Chapter 19 — Fire Origin and Cause Determination

2. Learning Objective 1
Explain ways to recognize obvious signs of the area of origin.

3. The area of origin contains several pieces of important information.
Precise point of origin, ignition
Greatest amount of damage, debris
Area of origin
Potentially lethal concentrations of gas present
Monitor air
Wear full PPE
Assume

4. Arson – Criminal charges
Debris on scene contains fire cause indicators and must remain in place.
May be used in court
Arson – Criminal charges
Courtesy of Donny Howard

5. Remember from on scene – What you
You must control evidence and remember information from the incident as much as possible.
Chain of custody
Required in legal cases
Control evidence
See
Smell
Hear
Remember from on scene – What you

6. CAUTION
You should minimize fire suppression and overhaul activities that could destroy important evidence regarding the origin and cause of the fire.

7. Several factors will influence locating the area of origin and the overall success of the investigation.
May be apparent, if not
Follow from least damage to most
Critical to overall success
Identify witnesses
Secure scene
Note initial scene
Incident Commander or fire/criminal investigator
Determine point fire started, fire cause
Protect or collect evidence
Wildland or ground cover fire
May require experienced investigator

8. The search for area of origin at a structure fire begins outside.
Courtesy of Donny Howard

9. You should know actions to take when the origin cannot be determined.
Delay overhaul beyond locating, extinguishing fires
Protect scene
Establish scene security

10. Preliminary assessment and exterior examination require specific tasks.
Exam scene to determine
Document, preserve
Specific observations

11. Fire indicators to use:
The interior examination begins in the area of least damage and works toward the area of greatest damage.
Fire indicators to use:
Fire patterns
Melted metal, glass
Degree of damage
Courtesy of Donny Howard

12. Charring on floors and vertical surfaces can indicate useful information.
Where fuel burned in that location
Face toward area or point of origin
Courtesy of Donny Howard

13. Area of origin and fire spread factors should be closely examined.
Multiple areas of origin
Factors affecting fire spread
Be aware of general patterns
May indicate intentionally set
Unintentional may give same appearance
Materials in fire’s path
Building features, layout
Ventilation openings
Fire load
Fire suppression tactics
Activation of suppression systems
Call investigator if there is a question

14. Total structural fire loss presents unique investigation challenges.
Courtesy of Donny Howard

15. Exterior fires involve several different types of materials.
Stored materials
Debris
Trash
Rubbish
Ground cover or vegetation

16. Ground cover fires require specific understanding of several concepts.
Basic fire behavior
Effects of winds
Topography
Natural fuels on fire spread
Burns outward in all directions

17. Fire burns in equal directions when on flat ground and without wind.

18. The rate and direction of spread of ground cover fires are affected by several components.
Wind direction
Wind velocity
Terrain/topography
Types of fuel
Ambient temperature
Relative humidity
Moisture content of fuel

19. Ground cover fires require specific understanding of several concepts.
Evidence of slower, less intense fire growth
Unburned materials
Effects of flame on fuels less than at head
Area of origin may display
Backsides of grass, trunks protected
Grass will fall toward area of origin
White ash product of more complete combustion
Radiant heat affects adjacent fuels

20. Finding the area of origin for vehicle fires is similar to the structural process.
Search for area of origin
Interview witnesses, firefighters
Examine exterior, interior

21. Vehicle fires require knowledge and practice of several safety guidelines.
Ensure undeployed air bags inoperable
Ensure shock absorber bumpers inoperable
Hybrid, electric car considerations
Do not cut posts that contain restraint systems
Know where large capacity or multiple fuel cells may exist
Hydraulic system considerations
Check trunk area for flammable/ combustibles

22. WARNING
Do not attempt to access or examine a vehicle unless you know how to do so safely.

23. REVIEW QUESTION
What ways can a Firefighter I recognize obvious signs of a fire’s area of origin?

24. Learning Objective 2
Describe the relationship between fire cause classifications and cause determination.

25. Fire cause determination is a critical step in the investigation process.
Look for
Competent ignition source
Ignition sequence
Determination can
Document causes of fire
Indicate trends in unsafe behavior
Indicate defective equipment, design flaws
Indicate malicious, illegal behavior

26. Open flame, ember, or torch
The National Fire Incident Reporting System (NFIRS) reports several causes of fires in structures.
Incendiary
Open flame, ember, or torch
Other heat, flame, or spark
Smoking materials
(Cont.)

27. Electrical or lighting equipment
The National Fire Incident Reporting System (NFIRS) reports several causes of fires in structures.
Lightning, natural
Heating equipment
Cooking equipment
Electrical or lighting equipment
(Cont.)

28. The National Fire Incident Reporting System (NFIRS) reports several causes of fires in structures.
Heating, ventilating, and air-conditioning (HVAC) appliances
Other equipment
Exposure
Children playing with matches, lighters, or other ignition sources

29. There are four types of fire cause classifications.
Accidental
Natural
Incendiary
Undetermined
Courtesy of Iowa Fire Service Training Bureau.
Courtesy of Donny Howard

30. There are several obvious signs of cause you should look for.
Courtesy of Bob Espositio

31. DISCUSSION QUESTION
What are some visual signs that may determine the area of origin for ground cover fire?

32. Absence of an obvious ignition source can help investigations.
Eliminate some causes
Focus on other causes

33. REVIEW QUESTION
What is the relationship between fire cause classifications and cause determination?

34. Learning Objective 3
Recognize signs of arson.

35. You will need to provide information if an incendiary or undetermined initial cause is indicated.
Gather based on
Observations
Different personnel may perform formal investigation
Local or state fire investigators
Law enforcement officials
(Cont.)

36. You will need to provide information if an incendiary or undetermined initial cause is indicated.
Time of day
Weather, natural hazards
Manmade barriers
People leaving the scene
Courtesy of Donny Howard

37. Additional information should also be gathered to assist investigators.
Time of arrival and extent of fire
Wind direction and velocity
Doors or windows locked or unlocked
Location of fire
(Cont.)
Courtesy of Donny Howard

38. Additional information should also be gathered to assist investigators.
Containers or cans
Burglary tools
Familiar faces
Courtesy of Donny Howard

39. Conditions should also be observed to provide information for investigators.
Unusual odors
Abnormal behavior of fire when water applied
Obstacles hindering fire fighting
Incendiary devices
(Cont.)

40. Structural alterations
Conditions should also be observed to provide information for investigators.
Trailers
Structural alterations
Fire patterns
Heat intensity
Courtesy of Donny Howard
(Cont.)

41. Availability of documents Fire detection and protection systems
Conditions should also be observed to provide information for investigators.
Availability of documents
Fire detection and protection systems
Intrusion alarms
Location of fire
(Cont.)

42. Equipment or inventory
Conditions should also be observed to provide information for investigators.
Personal possessions
Household items
Equipment or inventory
Business records
Courtesy of Donny Howard

43. REVIEW QUESTION
How can a Firefighter I recognize signs of arson?

44. Learning Objective 4
Describe the importance of preserving evidence.

45. Learning Objective 5
Explain techniques for preserving evidence.

46. Preserving evidence requires understanding certain principles.
Responsibility of all at scene
Do not determine what is/is not unless qualified
Protect everything that looks odd, suspicious

47. There are several important aspects of protecting the fire scene.
Scene security - First
Early security measures
Restrict scene access
Protect potential evidence
Minimize suppression, overhaul activities that could destroy information
First-arriving investigator
May adjust or implement new measures
Decision factors
May request monitoring of each entrance, exit to document individuals on scene

48. Establishing a scene perimeter requires specific knowledge.
Explosions
Structure
Courtesy of Ron Moore, McKinney (TX) Fire Department

49. There are several ways to establish perimeters that are both recognizable and enforceable.
Ensure initial larger than needed
Ensure visible, recognizable
Use law enforcement or firefighters to control

50. Procedures for criminal investigations also impact scene security practices.
Keep entry log
Permit access to only those authorized
Move personnel to staging area when tasks complete
Ensure others always escorted
Mark potential evidence to prevent disturbing

51. There are several techniques used to preserve evidence.
Keep evidence untouched, undisturbed
Do not gather or handle unless necessary to preserve
Document all actions
Follow department SOPs
(Cont.)

52. There are several techniques used to preserve evidence.
Avoid walking on, cross-contaminating, or destroying
Avoid excessive water use
Protect footprints, tire marks
Close dampers and other openings
Leave charred documents
Protect documents from air flow

53. Overhaul operations can be detrimental to an investigation.
May destroy potential evidence
Delay until origin and cause determined
Begin once critical evidence protected

54. Even when a scene is secure, contamination or spoliation can occur.
Courtesy of Donny Howard

55. Follow local procedures when finalizing operations and investigations.
After investigation complete
Secure structure, turn over to occupant
Perform according to local SOPs
Debris removal
Follow local protocol
May be last activity
Prevent rekindle
Separate unburned
Dump debris where not visible if possible

56. REVIEW QUESTION
What are some techniques firefighters can use to preserve evidence?

57. Summary
One of the most important responsibilities is protecting evidence.
Use appropriate caution in the area of origin.
A thorough investigation can be conducted to determine the exact cause of the fire.