Fire Debris Fire Investigations and the Forensic Lab

Fire Debris, Fire Investigations and the Forensic Lab Are We Missing Things? Or, Keeping Up with the Dogs Dr. John D. De. Haan

The need for “science” in fire scene investigation n n Started to change in the 1980’s with new, science-based texts and a growing awareness of the need to get it right. NFPA began the process to create the 921 Guide Court decisions (Daubert, Kumho, Joiner, Benfield, et al. ) forced fire investigation to become more science-based. The “Scientific Method” is expected. Experts Have to Support Their Conclusions and demonstrate reliability, acceptance, and use of published, peer-reviewed data.

Fire Investigations and the Forensic Lab n n If the investigator has no access to reliable answers based on good science, he or she will turn to less reliable sources such as those the oral history promulgated (often erroneously). The answers needed by today’s investigators go far beyond “Was there an ignitable liquid in the debris? ”

CRIMINALISTICS Purpose: Aid in Reconstructing Events and Human Activities Link suspect and scene or victim and suspect n n n Debris containing suspected volatiles Liquids Charred or burned paper documents Clothing and shoes Tools and tool marks n n n Dry blood stains DNA/saliva Glass fragments Paint chips Hairs and fibers Firearms

Debris containing suspected volatiles n n The most requested service Well-studied and Documented by ASTM practices n Isolation of volatiles from debris E 1386: Solvent extraction n E 1388: Headspace sampling n E 1412: Passive headspace (C-strip) n E 1413: Dynamic headspace (charcoal tube) n E 2154: SPME n

Method Selection E 1412: Most commonly used, easy, low cost, non-destructive, wide dynamic range n May miss light ends (Hydrocarbons under C 7) if sampling time is too long n May miss heavy ends (hydrocarbons over C 18) if sampling time is too short or temperature is too low n Uses solvent extraction from carbon strip n

Gas Chromatographic Analysis n ASTM E 1387: GC-FID: Characterization by peak pattern and retention times n Original method: low cost, universal range n Well-suited to: gasoline, paint thinner, kerosene, diesel, light distillates, and “miscellaneous” class: blends and nondistillate products n Proliferation of new “custom” petroleum products and non-petroleum products n “De-certified” by ASTM E-30 in 2010 n

Gas Chromatographic Analysis n n n n GC/MS became necessary to make many identifications First published as ASTM E 1618 in 1994 Capable of “separating” aliphatics, aromatics, cycloalkanes, and unsaturated compounds Retention times, peak profiles, target compounds, aromatic: aliphatic ratios are now criteria Now multiple classifications: seven major classes, divided by boiling point range, plus automotive gasoline, for a total of 21. E 1387 dropped as a recommended method in 2010. Heavy products no longer separated into kerosene class v. fuel oil class

GC/MS: The Only Answer? With solvent injection methods, most GC/MS operators sacrifice all peaks that elute before the solvent (diethyl ether, dimethyl ether, or carbon disulfide) n This means that many light products including: ethers, ketones, alcohols and C 6 range hydrocarbons are not recorded. n These may be critical to the evidence. n

Jumping straight to selected ions n n n The overall pattern of peaks is very important in the characterization process Start with the TIC! Skipping straight to looking for aromatic v. aliphatic peaks or even target compounds can result in misleading conclusions

Blind Spot Because the heavy distillates are no longer split, it is OK to report “heavy petroleum distillate” and list kerosene and diesel fuel as candidates n This has led to mischaracterization of kerosene as diesel fuel and vice versa (not by the analyst but in court by the investigator or the prosecutor). n n The analyst has to know what issues are important and modify the technique used.

Lab Analysis n n Not just for Volatile Accelerants! Identification of Fuels Laboratory Identification n By chemical, physical, or microscopic methods n Field Tests n Fire Tests n

Fire Investigations and the Forensic Lab n Furnishings and Clothing: Are they natural fibers – cotton, linen, wool? n Are they synthetic – polyester, polypropylene, nylon, acrylic, or ? ? ? n Are they thermoplastic, or thermosetting, or elastomers? n Melting points? Ignition temperatures? n What volatile products do they generate? n Foam – polyurethane, polyether, or latex? n Are there fire retardants present? n

What Can the Lab Tell? n n General type of fuel may help identify or exclude competent ignition sources. Is the Fuel First Ignited Cellulosic? n Cellulosic: Derived from Plants n n n n Wood Paper Cotton Linen Cardboard Susceptible to smoldering Crumbly grey/black ash on burning White smoke Cellulosic fuels are susceptible to hot surface/glowing ember ignition

What Can the Lab Tell? n Is the Fuel First Ignited Synthetic? n Most Synthetics are petroleum derivatives Nylon n Polyethylene n Polystyrene n Polyester n Rarely ignitable by smoldering/hot surface source n Easily ignited by open flame n Tend to melt and shrink away from heat n Most do not sustain smoldering combustion n

What Can the Lab Tell? n Synthetics: May be thermoplastic – melts without degrading n May be thermosetting (resin) – degrades, chars, may smolder n n Other fuel types: Elastomers (rubbers): Synthetic or natural n Leather – Wool – Silk: Proteinaceous (from animals) n

Field Testing n Even a simple IST (ignition susceptibility test) has a pedigree: NFPA 705: Field Flame Tests for Textiles and Films – Recommended Practice 1997 n n n Small flame (lighter or match) held to bottom edge or corner of small sample held vertically in air. Observe flame color and behavior Observe smoke color and production odor Blow out and observe smolder (if any) Test ash texture

Fire Investigations and the Forensic Lab n WHY? n Because the investigator will be expected to justify his or her conclusions about ignition, flame spread, and size of the fire on that data. Cigarettes will not ignite most synthetics but will ignite most cellulosic materials. n Open flames will quickly ignite most synthetics or blends, but then what will the fabric do? n Self-heating processes do not result in ignition of thermoplastic substrates. n

CRIMINALISTICS Purpose: Not Just for Identifying Things! Aid in Reconstructing Events and Human Activities Link suspect and scene or victim and suspect n n n Debris containing suspected volatiles Liquids Charred or burned paper documents Clothing and shoes Tools and tool marks n n n Blood stain patterns DNA/saliva Glass fragments Paint chips Hairs and fibers Firearms

Criminalistics (Non-Fire) Evidence n n n Investigators must be aware of proper collection and preservation methods for each type of evidence The lab needs to get involved in training! Chain of custody traces an item of evidence from its discovery to court. Spoliation is the destruction or alteration of evidence. ASTM E 860 establishes practices for examining and testing of evidence which may be involved in criminal or civil litigation.

Other Relevant ASTM Guidelines n n n ASTM E 620: Practice for Reporting Opinions of Technical Experts ASTM E 678: Practice for Evaluation of Technical Data ASTM E 1188: Standard Practice for Collection and Preservation of Information and Physical Items by a Technical Investigator ASTM E 1459: Standard Guide for Physical Evidence Labeling and Related Documentation ASTM E 1492: Receiving, Documenting, Storing and Retrieving Forensic Evidence

Fire Investigations and the Forensic Lab n n n Flash Point? Melting Point (or Softening Point)? Does this material burn by smoldering, flaming, or both? Ignition Conditions – vapor pressure, autoignition temperatures, conditions? What would be the effect of enhanced oxygen or reduced oxygen concentrations?

Fire Investigations and the Forensic Lab n n What Is That Mess? What Was It and How Did It Get That Way n n n n Physical exam UV/ALS X-rays Elemental analysis SEM Broken by mechanical force, shock, or heat? Exemplars?

Fire Investigations and the Forensic Lab n Clothing items: Impact or transfer patterns - actions n Thermal – scorching, melting, charring, color changes – position and posture of wearer n Bloodstains – presence, patterns, toxicology n Thermal properties – conductive or transparent to infrared – related to burns or protect areas on body n

Fire Investigations and the Forensic Lab n n n Shoe, tire, or tool impressions Latent fingerprints Body fluids - DNA

Fire Investigations and the Forensic Lab n n What can the broken glass and bloodstains on this door tell the criminalist? DNA alone doesn’t tell the whole story!

Fire Investigations and the Forensic Lab n n Recognition of trace evidence – glass, fibers, paint, soil - and toolmark evidence and their forensic significance. Who else can or should do it?

Fire Investigations and the Forensic Lab n Glass: n n DNA on the mouth of the bottle! Thermal or mechanical break? Type? Match to Source? Reconstruction?

Fire Investigations and the Forensic Lab n New Innovations Need to be Properly Tested. Sniffers n Absorbent materials n Containers n UV and ALS detection of “accelerants” n CANINES n GC/MS/MS n

Keeping Up with the Dogs n n n In the late 1980’s canine “accelerant detection teams” were introduced. Their sensitivity to odors was quickly proven superior to lab methods. Conflicts grew when handlers insisted that a canine alert was proof of the presence of an ignitable liquid even when the lab results were negative.

Keeping Up with the Dogs n n Analysts were forced to improve the sensitivity of lab methods to the ppb levels of the canines. Then we discovered that there were many products (carpet, clothing, shoes, copy paper, etc. ) that contained traces of solvents from their manufacture. The issue was not of sensitivity but of the selectivity needed to discriminate between innocuous contaminants and significant residues of real accelerants. GC/MS is the only defensible technique.

Fire Investigations and the Forensic Lab n n Now that we can be as sensitive as the dogs, the question became: Is There Such a Thing as “Too Sensitive”? What Do We Know About the Substrate and Its Possible Background Contributions? What control or comparison samples exist? Can “Old” residues be significant?

Fire Investigations and the Forensic Lab This fire in Pennsylvania killed two elderly people. An adult son escaped and was charged with their murder based on burn patterns in the room of origin and the presence of traces of highly evaporated gasoline in the wood floor (but not in the carpet or pad).

Fire Investigations and the Forensic Lab n New petroleum products and new uses for not-so-new products have added to the difficulty of interpreting GC results GC/MS almost mandatory today n Aware of contributions of fuels involved n Comparison samples essential n Substrates AND products n Pyrolysis products in both oxygenated and oxygen deprived conditions n

Fire Investigations and the Forensic Lab n n n We cannot come to correct conclusions without context. We cannot deliver valuable analyses by “rote” methods (unlike drugs, blood alcohol or even DNA). We owe it to our clients to offer the best array of services Many of the reliable and useful techniques are so rarely used that no “ASTM” technique exists BUT That does not mean we should not offer them as long as they are based on good science!

WE must prepare criminalists with the broad scientific knowledge AND the reasoning capacity to evaluate real evidentiary problems and properly select, use, and defend the procedures used to solve those problems. Thank you! John D. De. Haan, Ph. D. , F-ABC, CFI, FFSSoc Fire-Ex Forensics, Inc. 3505 Sonoma Blvd #20 -314 Vallejo CA 94590 707 643 -4672 707 -643 -4682 (Fax) jddehaan@fire-exforensics. com