February 1, 2019 Vol. 2, No. 2

Fire Investigation: Historical Perspective and Recent Developments

It happens when you get old. People ask you to write things for them. I have been asked twice in the last six months to write a “review” article about the progress in fire investigation over the last 45 years, which happens to coincide with my time in the profession. I accepted the first invitation and declined the second, fearing that I would fall into a “self-plagiarism” trap. The second editor understood why I had to decline.

The review, entitled “Fire Investigation: Historical Perspective and Recent Developments,” was published in the January 2019 edition of Forensic Science Review. Many critical turning points in the evolution of fire investigation are covered, including the development of NFPA 921, the Lime Street Fire, The Oakland Hills study, and the acceptance, however reluctant, of the need for science in fire investigations. More recent developments include a better (if still imperfect) understanding of the impact of ventilation on fire patterns, the continuing effects of the NAS report, and the work of the OSAC Subcommittee on Fire and Explosion Investigations.

You can download a copy of the paper here. http://www.firescientist.com/publications.php (It’s only 8 pages long.)

Arson/Homicide Case Dismissed in Indiana

In December 2017, my friend Denny Smith of Premier Fire Consulting <http://premierfireconsulting.com> asked me to review some chemistry in an arson/homicide case he was working on. As a result of his work and mine, the newly elected District Attorney in Porter County Indiana agreed that he had no case, and dismissed all charges. The Chicago Tribune’s January 4 story on the case can be found here: https://www.chicagotribune.com/suburbs/post-tribune/news/ct-ptb-fegely-charge-dismissed-st-0105-story.html. The case of Indiana v. Fred Fegley will be the Case Study of the Month for March.

When Arc Mapping Works, It Really Works Well (Sometimes)

February's case study involves the successful use of arc mapping, to bring closure to the family of a fire victim who had who initially had concerns about the cause of the fire. The deceased had amassed a considerable fortune, and his family was concerned that his long time fiancé, whom they suspected of having an affair with someone else, had arranged the fire. They contacted a family friend, who had previously worked with me, and he requested that I give the scene a fresh look about a year after the fire. Fortunately, the scene was still intact. The public sector investigator was happy to have some help with this cold case, and provided extensive access and co-operation. The arc mapping saved the day.

Case Study of the Month

This month's case study comes from a an investigation I conducted in which arc mapping proved to be instrumental in definitively identifying the origin of the fire, which, in turn, allowed for a definitive determination of cause and classification.

Arc Mapping Proves the Origin and Cause of a Fatal Fire

Since 2001, NFPA 921 has recommended arc mapping as one of four tools to be used in origin determination. Chapter 18 on Origin Determination opens with the following:

18.1.2 Determination of the origin of the fire involves the coordination of information derived from one or more of the following:

(1) Witness Information and/or Electronic Data. The analysis of observations reported by persons who witnessed the fire or were aware of conditions present at the time of the fire as well as the analysis of electronic data such as security camera footage, alarm system activation, or other such data recorded in and around the time of the fire event

(2) Fire Patterns. The analysis of effects and patterns left by the fire (see Chapter 6)

(3) Arc Mapping. The analysis of the locations where electrical arcing has caused damage and the documentation of the involved electrical circuits (see Section 9.10)

(4) Fire Dynamics. The analysis of the fire dynamics [i.e., the physics and chemistry of fire initiation and growth (see Chapter 5) and the interaction between the fire and the building's systems (see Chapter 7)]1

The following is an excerpt from Chapter 3, “Fire dynamics and fire pattern development” in Scientific Protocols for Fire Investigation, Third Edition (CRC Press 2018) discussing the utility of arc mapping.

Arc mapping as a tool for origin determination has not been without controversy. The fact that most conductors in an electrical system are not compromised early in the fire has led one author to conclude that it is useful in less than 1% of cases. The author stated, “It is essential to identify explicitly the exact hypothesis being invoked, and how the conclusions follow from that hypothesis.” 2 This position provoked a response from researchers at the ATF Fire Research Laboratory, who argued against removing this useful tool from the investigator’s toolbox.3

This author has found arc mapping to be a useful technique on several occasions, and recommends always considering its use to both develop and test hypotheses, just as one would use any other pattern.

As an example, the fatal fire that damaged the den shown in Figure 3.42a caused severe damage throughout the room and caused the floor of the room above to be consumed. The homeowner had built a clever (but not safe) heat exchanger next to the fireplace to supplement the central furnace. The wiring in the room exhibited no arcing, except in the area behind the stone facade. Because of how the heat exchanger fan was powered, the arcing damage shown in Figure 3.42b could only have occurred if the origin of the fire was behind the stone facade, where no human access was possible. Thus, arc mapping allowed a fire that had been deemed “undetermined but suspicious” could be correctly classified as an accidental fire.

Figure 3.42 (a) The homeowner had constructed a heat exchanger behind the stone façade surrounding this fireplace. The heat exchanger was in use at the time of the fire. (b) The location of this arced wire behind the stone façade allowed a determination that the fire started in the hidden space.

A more complete report of the fire in question, as well as references 2 and 3, may be found at this link: https://app.box.com/s/43inykpxum14xsqqjsk2h7wt1quwjjbq


1. NFPA 921, Guide for Fire and Explosion Investigations, 2017 Edition

2. Babrauskas, V. (2017) Arc mapping: New science or new myth? Presentation to the 2017 Fire and Materials Conference, Available at https://doctorfire.com/pages/ArcMappingFM.pdf

3. ATF Fire Research Laboratory (2017) Technical Bulletin 002, Available at https://www.atf.gov/file/114497/download

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