4. Fire Investigation

4. Fire Investigation firefighter-taken-to-hospital-after-fighting-house- The Chemistry and Physics of Fire Arson Investigation Focus Areas 1. Proof of Incendiarism: Comes from an examination of the fire scene by a qualified cause and origin investigator. 2. Proof of Opportunity: Focuses on the security of the building/place when the fire was discovered and who had access. 3. Proof of Motive: focuses on the Insured’s Financial Condition, profit/loss from questions, cash flow, revenge, anger, etc. 4. Miscellaneous Connecting Evidence: Includes. An examination of the insured’s insurance history, operability of fire and burglar detection systems, how insured learn about the fire, etc. The Fire Tetrahedron V Pattern The Fire Tetrahedron • Take one away and the fire goes out. s://www.thinglink.com/scene/7 Chemistry of Fire - Oxidation • CH4 + 2O2 —> CO2 + 2H2O • 4Fe + 3O2 —> 2Fe2O3 Physics of Fire • Naturally birds up and out (V Pattern) • Investigate any burns in other directions Transfer of Heat • Conduction: Transfer of heat between substances that are in direct contact with each other. • Convection: Thermal energy is transferred from hot places to cold places when warmer areas of a liquid or gas rise to cooler areas in the liquid or gas. • Radiation: Heat transfer that does not rely upon any contact between the heat source and the heated object. • Heat is transmitted through empty space by thermal (infrared) radiation. Important Definitions • Oxidation: Oxygen combining with other substances to produce new products (e.g. rust). • Heat of Combustion: The excess heat energy given off as heat and light. • Flashover: The temperature at which anything that can combust will combust (1100ºF). • Exothermic Reaction: One that gives off heat energy. • Glowing Combustion: Combustion on the surface of a solid fuel in the absence of heat high enough to pyrolyze the fuel (e.g. cigarette). • Pour Pattern: A pattern left by the vaporization of flammable liquids. • Ignition Temperature: The temperature a fuel must reach to allow the heat energy input to exceed the energy barrier. • Flash Point: The lowest temperature at which a liquid gives off sufficient vapor for combustion. • Flammable Range: The concentration range between the upper and lower limits for combustion (gasoline = 1.3% - 6%). Chemistry of Fire - Solids & Liquids • Liquids are heated and the vapors that form burn. • Solids decompose into gaseous products which burn (pyrolysis). • Solid and liquid matter do not burn! Only gaseous matter burns! Combustible & Smoke Color Wood/Paper/Cloth: Gray/Brown Cooking Oil: Brown Oil/Kerosene/Gasoline: Black Accelerants Spread the fire around quickly Pour Pattern Speed up burning rate Gasoline, Kerosene, Alcohol etc. The Investigation Firefighters Look For: • Smoke and flame color • The crowd • Cars in area • Owners/Residents of property • Knowledge of everyone • Beginning of the Investigation Smoke & Fire Color • Temperature of fire • Type of material burning Temperature & Event • 1000ºF: Steel loses 1/2 strength • 1220ºF: Aluminum melts • 1400ºF: Glass softens • 1980ºF: Copper melts • 2900ºF: Sand melts Gasoline Burning Fire Setting Mechanisms • Ignition Devices: To start the fire (matches, montebello calif wednesday dec capsules, chemicals, gas). • Plants: To feed the fire (newspaper, rags, wood shavings, waste). • Trailers: To transport the fire (accelerant, rags, newspaper, black powder). • Accelerant Residues: Residues left after the fire by flammable liquid Searching The Fire Scene • From the least burnt area to the most burnt area. • 4th Amendment - You can search any room affected by the fire without a warrant. • Collection of Arson Evidence - Warrantless search (exigent circumstances) • Accelerants, ignition devices, interviews Fire Evidence • Smoke Demarcation Line: Damage due to heat not fire. • No smoke damage to one side of door: Door was closed during fire. • Burn patterns on floor: Remove furniture from the floor. • No damage to contacts or internal wires: Not electrical fire. • Low Burning/Alligatoring: High Heat Smoke Demarcation Line n_study.pdf"https://ssem.eku.edu/sites/ssem Flashover - 1100ºF • The temperature at which anything that can combust will combust (including people). • Death of any person trapped in the room. • End of growth stage - Fire is in fully developed stage. • Change from a contents to a structural fire. • If there is not enough heat present, the fire will not achieve a high enough temperature to produce a flashover. Stages of a Fire Evidence Collection & Analysis Collection of Evidence • Photograph ALL evidence first! • Use appropriate tools (hands, small tools, shovels). • Wear gloves and always store in airtight containers. • Label all containers and seal with evidence tape. Analysis of Evidence • Many different types of tests. • Accelerants. Arson Evidence Can • Gas Chromatograph: Separates all components of accelerants. investigation.html"https://www.arrowhea Determining Cause of Death • Fire: Soot/Carbon Monoxide in Blood • Prior to Fire: No Soot/Carbon Monoxide in Blood • Possible Homicide (Foul Play) Pugilistic Stance • Contraction of muscles caused by extreme heat (can break bones and skin). • Appears to be a defensive posture. Pugilistic Stance biology/body- Cause & Origin Investigation Motives for Arson 1. Effort to Hide Crime 17. Fraud (Insurance) Revenge Riots/Vandalism Thrill (Pyromaniac, Juvenile, Sexual) Terrorism (e.g. Drug 18. Jealousy Dealer) Fire Scene Red Flags 1. Large Amount of Damage 19. Low Burning (Altitude) 20. Unidentifiable Origin 21. No V Pattern 22. Lack of Accidental Cause 23. Separate/Unconnected Fires 24. Unusual Burn Patterns 25. Windows Blown Away 26. Forced Entry 27. Missing Inventory 28. Missing Personal Items 29. Previous Fires 30. Unkempt Yard “For Sale” Sign (Long Time) Loss (Property Damage Fuel cans Fire Extension Beyond Perimeter of Structure 1. Contact Incident Commander 31. Interview First Responding Unit 32. Interview First-In FireFighter 33. Walkthrough First-In FF 34. Establish Ingress/Egress Point 35. Establish Perimeter 36. Security of all Doors/Windows Insurance Claim) Fires Occurring Near Insurance Expiration Date Fires Occurring at Night Over Insured Property Insure Out of Property for Sale Town/Alibi Alarm System not Set Recently Issued Policy Decline in Utility Use Insured Overly Pushy Liquor (License to Sell Familiarity with Insurance Terms Behind on Mortgage Previous Claims Order of Operations Hand Delivered Proof of Liquor) License Revoked Stock Obsolete Many Antiques “Destroyed” Search Surrounding Photograph Scene Area for Evidence Secure Witnesses Find all Witnesses Possible Exterior Examination Examine Crowd Create Potential Suspect List Examine Block Canine Search All Areas Walkthrough Rule-Out (Electric, Tenant/Owner Location of Room Contents Incendiary, Accidental) Scene Diagram Paper Trail (Bank Statements, Police/Fire Reports) Fire Setting Mechanisms • Can be intricate mechanical/chemical contraption that will go off hours to weeks after it is set. • Allows arsonists to get a safe distance away and provides them with an alibi. Ignition Devices 1. Matches: Source of most fires. • Juveniles & Pyromaniacs hold matches to pile of trash. • Sophisticated arsonists may combine matches with cigarettes to create a delay. • Used in connection with mechanical devices (telephones, alarm clocks, doorbells). • Preserve any burnt matches found (physical match with those of suspect). 2. Capsules: Gelatin capsules filled with water activated mix (e.g. silver nitrate magnesium powder, sugar-sodium peroxide, sulphuric acid). 5. Candles: Very effective, but leave wax deposit (3/4 inch diameter burns at about 1 inch/hour). • Place the candle in an easily combustible container (in or close to accelerants). 4. Chemicals: Ignite upon contact with air (Phosphorous) or water. • Most leave residue and/or have a particular odor (many arsonists don’t use chemicals properly). 5. Gas: Venting from the kitchen stove comes into contact with pilot light and explodes (lighterthan-air gas rises, then sinks to escape). • Often used in suicide attempts (arson is always a possibility). • Well recognized gas odor. • Time elapsed between initial release and explosion depends on room size, number of openings, type of gas, etc. • For a standard 10 x 15 ft well sealed kitchen: • Single Burner: 5 hrs • Oven Jets: 2 hrs • 4 Burners & Oven: 1 hr