Forensic Science Assessments A Quality and Gap … Quality and Gap Analysis Fire Investigation July...

Copyright © American Association for the Advancement of Science 7/11/2017 1

Forensic Science AssessmentsA Quality and Gap Analysis

Fire InvestigationJuly 11, 2017


Context

▪ As advances in fire science are being made, investigators and attorneys are revisiting old cases; and what they are finding is chilling.

▪ John Lentini (one of the authors of this report) estimates that “a couple hundred” people are wrongly imprisoned because of outdated fire science and, according to the National Registry of Exonerations, 63 individuals have already been exonerated since 1991.

▪ We’ll never know for sure how many people have been wrongfully convicted based on methods that have not been empirically validated, nor how many criminal arsonists have not been indicted because of inadequate forensic tools.

▪ This report recommends needed research on fire scene investigation and fire debris analysis and, it is hoped, is read by judges, lawyers for the prosecution and defense, policy makers, law enforcement officers, laboratory scientists, funding agencies, and fire investigation practitioners.


Fire Investigation – A Primer

▪ Fire investigation includes two basic types of analyses -- fire scene investigation and fire debris analysis, done in the laboratory for the purpose of detecting and identifying ignitable liquids.

▪ Fire scene investigation is much more challenging than debris analysis for a number of reasons, including the extensive destruction of evidence caused by the fire and firefighting activities, the complex behavior of fire, and the generally inadequate understanding of fire chemistry and physics by many investigators.

▪ Several variables, including witness statements, fire patterns and fire dynamics, are essential to determining fire origin and cause.

▪ Fire debris analysis in the laboratory focuses on the presence and identity of ignitable liquids, a process based on established scientific principles.

▪ The validity and reliability of fire debris analysis is well established due to several organized efforts within the discipline including the Technical/Scientific Working Group for Fire and Explosion Analysis (swgfex.org), and the Criminalistics Subcommittee of the American Society for Testing and Materials (ASTM) E30 Committee on Forensic Sciences.


Conclusions and Recommendations- Fire Scene InvestigationOrigin and Cause Determination

▪ Conclusions▪ While much is known about the behavior of fires in building enclosures, using that knowledge to

determine where a particular fire started and what caused it remains very challenging; an incorrect determination of a fire’s origin generally leads to an incorrect determination of its cause.

▪ Computer-based deterministic fire models can be used as one means of testing different hypotheses regarding the origin and development of a fire, but such models cannot generally be used alone to determine the cause of a fire. Uncertainties exist concerning the use of fire models when they are applied to fire cause determination.

▪ Recommendations▪ To improve the analysis of a fire’s origin and cause, tests should be run in both reduced and full scale,

using multiple compartments and multiple openings, fully documenting the aftermath; with the burning of different materials under a range of realistic fire conditions; and by lighting fires in identically constructed compartments.

▪ When a physical fire test is conducted, the fire scenario being tested should also be simulated with a deterministic fire model to evaluate the accuracy of the model and to better understand uncertainties associated with the model.


Conclusions and Recommendations- Fire Scene InvestigationLocating Ignitable Liquid Residues (ILRs) in Fire Debris

▪ Conclusions

▪ A well-trained canine detection team is the current “gold standard” for locating samples at the fire scene that are likely to test positive for ignitable liquid residues in the fire debris analysis laboratory. Canines are advantageous because they provide immediate feedback and are mobile, allowing them to search a large space in a very short time.

▪ Many substances are produced during a fire, but investigators are currently in a position to look only for evidence of ignitable liquids, for which there is currently validated instrumentation.

▪ Recommendations

▪ Testimony that relies on canine alerts only, without supporting laboratory results, should not be used in court proceedings.

▪ New technologies, as well as additional training aids and research on new methods need to be developed for measuring canine performance that could enhance their effectiveness.

▪ Comparative research assessing the effectiveness of technologically more innovative field tools against the effectiveness of canine use should be a research priority.


Conclusions and Recommendations- Fire Scene InvestigationReliability and Validity

▪ Conclusion

▪ Little is known about the consistency and accuracy of conclusions among experienced investigators when presented with the same data.

▪ Recommendations

▪ The reliability of conclusions when fire investigators are presented with similar data of fire origin and cause should be studied. This will allow the calculation of both error rates and the reliability of investigators’ conclusions.

▪ Not only should the reliability of investigators’ conclusions or diagnoses be established, but research should also be done on the validity of those conclusions or diagnoses. The use of “test fires” will help to establish a “ground truth” against which the validity of investigators’ conclusions can be assessed.

▪ The data generated by the research on reliability and validity should be incorporated into a database that could be used to develop standards for identifying the origin and cause of fires and serve as a resource for the education and training of fire investigators.


Conclusions and Recommendations- Fire Scene InvestigationCognitive Bias

▪ Conclusions

▪ Interpretation of the evidence regarding origin and cause is often subjective and depends to a significant degree on human cognitive factors.

▪ Evidence from other domains, as well as within forensic science, suggests that there are practical ways to mitigate and minimize bias (such as, Linear Sequential Unmasking).

▪ Recommendations

▪ Given what is known about the role of cognitive bias in interpretation and decision making, the scientific work done and reported by fire scene investigators should be separated from other components of the fire investigation.

▪ Case management interventions should be adopted that shield fire scene investigators from information irrelevant, but potentially biasing, for assessing the scientific evidence critical to determining fire origin and cause.


Conclusions and Recommendations- Fire Scene InvestigationEducation, Certification and Experience

▪ Conclusions

▪ There are insufficient educational and proficiency testing requirements for fire scene investigators.

▪ There is currently no scientific basis for concluding that the accuracy of certified fire investigators, in particular, is better than the accuracy of non-certified fire investigators.

▪ Recommendations

▪ Education and training for fire investigators should cover the issue of human cognition and cognitive bias, as well as what has been discovered in the reliability and validity testing discussed earlier. The training could be done through live training simulations as well as online with photographs and videos or other depictions of test fires in which the origin and cause are known with certainty.

▪ The effects of education, training, and certification on fire investigators’ ability to determine fire origin and cause should be further studied.


Conclusions and Recommendations- Fire Debris AnalysisFrom Fire Scene to Laboratory

▪ Conclusion

▪ Although the science of fire debris analysis (analytical chemistry) is more mature and reliable than the science of fire scene investigation, there is still room for improvement in the knowledge base and in the practice of fire debris analysis.

▪ Recommendation

▪ Enhanced field tools should be explored to optimize sample identification and sample collection at the fire scene. Such tools include field-based mass spectrometers, field-based ignitable liquid residue (ILR) analysis that allows for rapid feedback to investigators, and more sensitive and specific electronic “noses” that can also detect the broad spectrum of potential ILRs.


Conclusions and Recommendations- Fire Debris AnalysisApplying Analytical Methods in the Laboratory

▪ Conclusion

▪ Several ASTM (American Society for Testing and Materials) standard test methods currently exist for the detection, extraction, analysis and interpretation of ILRs from debris, and these methods are generally, but not uniformly, used by the forensic science community.

▪ Recommendations

▪ Although research to improve ASTM standard test methods for extraction, separation, and analysis of ILRs would be useful, it is important to stress that the basic science is sufficiently developed and mature, and there is no reason for operational laboratories not to use these methods.

▪ Additional research to determine the performance of the ASTM methods under various real-world case scenarios is needed.


Conclusions and Recommendations- Fire Debris AnalysisChallenges in Analyzing ILRs

▪ Conclusions

▪ The changing nature of available fuels and consumer products requires the continual monitoring of possible sources of ILRs. An error in confusing background, combustion and/or pyrolysis products with an ILR would have serious and detrimental effects on the overall process of fire investigation

▪ Forensic scientists are asked to classify any of the potential flammable liquids into a limited number of chemical categories; although the existing standard is more than adequate for the vast majority of forensic casework, it is imperfect

▪ Recommendations

▪ Studies are needed on the differentiation of intentionally added ILRs from pyrolysis/combustion products and from products innocently present in materials at the fire scene. Comparison samples should be analyzed whenever possible.

▪ Additional work on the classification of ILRs is needed, particularly with regard to whether the existing classification scheme should be modified to accommodate new products on the market (e.g., more environmentally friendly fuels such as biodiesel and plant-based lamp oils).


Conclusions and Recommendations- Fire Debris AnalysisChallenges in Analyzing ILRs

▪ Conclusions

▪ There is a risk of missing ILR signatures due to advanced weathering and/or microbial degradation as time goes by

▪ There is debate in the fire debris analytical community on whether to limit the sensitivity of the methods used, with the justification that this approach reduces the risk of confusing ILRs with background products or with combustion/pyrolysis products

▪ Recommendations

▪ Experiments that explore the effects of weathering on different types of ILRs should be conducted. Such experiments could include subjecting ILRs in fire debris to the heat of a fire or to dousing with water.

▪ The impacts of potential microbial degradation on fire debris should be studied.

▪ The on-going debate on the use of more sensitive methods under certain conditions should be addressed in order to assess the actual effects of more sensitivity when examining ILRs.


Working Group

▪ José Almirall, Ph.D (CHAIR) - Florida International University(Chemistry)

▪ Hal Arkes, Ph.D - Ohio State University(Cognitive Psychology/Human Factors)

▪ John Lentini - President and Principal Investigator at Scientific Fire Analysis, LLC.(Forensic Science) CFI, D-ABC

▪ Frederick Mowrer, Ph.D - (California Polytechnic State University)(Fire Protection Engineering / Fire Science)

▪ Janusz Pawliszyn, Ph.D - University of Waterloo(Chemistry)


Project Staff

Mark S. Frankel – Former Project Director

Deborah Runkle – Project Manager

Michelle Barretta – Project Assistant

For the technical report, click here

For the “plain language” version, click here

Contact: [email protected]

https://www.aaas.org/report/fire-investigation

https://www.aaas.org/report/fire-investigation-plain-language-summary

Forensic Science Assessments A Quality and Gap … Quality and Gap Analysis Fire Investigation July...

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