LMU Law Review

A Model for Confronting Fire Investigation Errors

John J. Lentini

When faced with the challenge of defending someone accused of arson, counsel has several options but unless there is overwhelming evidence to indicate that this was in fact an arson, the first thing counsel should do is retain an expert.


Arson is one of the few crimes for which it is necessary to first prove that a crime was committed. Over this author’s 45-year career, many false accusations of arson have resulted in either civil or criminal litigation. As stated in the 2009 National Academy of Sciences (NAS) report:


The simple reality is that the interpretation of forensic evidence is not always based on scientific studies to determine its validity. This is a serious problem. Although research has been done in some disciplines, there is a notable dearth of peer-reviewed, published studies establishing the scientific bases and validity of many forensic methods.


This description applies to all of the forensic sciences, including fire investigation. Specifically related to fire investigation, the NAS report goes on:

…much more research is needed on the natural variability of burn patterns and damage characteristics and how they are affected by the presence of various accelerants. Despite the paucity of research, some arson investigators continue to make determinations about whether or not a particular fire was set. However, according to testimony presented to the Committee, many of the rules of thumb that are typically assumed to indicate that an accelerant was used have been shown not to be true. Experiments should be designed to put arson investigations on a more solid scientific footing.


The problem is that fires are destructive, and the aftermath of an accidental fire can often look exactly the same as the aftermath of an intentionally set fire. This confounding fact has led to many false accusations, false convictions, and even a wrongful execution.


According to the National Fire Protection Association (NFPA), there were about 387,000 residential structure fires in the United States in 2018. Of these, approximately 25,500 were declared to be incendiary. That means that every year, there are 25,000 chances for fire investigators to make a serious error. Even if the error rate is only 5%, that amounts to 1,250 miscalls per year. Given this author’s experience, a 5% error rate is wildly optimistic.

So the first question that counsel needs to address is “is this actually an arson fire?”

Following that, additional questions arise.

• Is this arson investigator actually qualified to render opinions?

• Did the investigator employ appropriate methodology in reaching his opinions?

• It is origin determination even a valid forensic science discipline? So far, attempts to demonstrate the validity of origin determination have failed.