Arson Investigation – After Decades of Junk Science

Arson is, of course, the intentional setting of a fire.  Arson is determined ex post facto by a “fire investigator”.  Fire investigators have historically  been people who started their career with a fire department, and inherited the job from a predecessor.  Training was largely “on the job” as a result of mentoring by superiors.  It might also be common for novice fire inspectors to attend a one week training course.  The body of knowledge concerning the causes, and locations of origin, of fires was anecdotal and passed from one generation of fire inspectors to another as folklore. Some have even compared the “old folklore science” of fire investigation to witchcraft.

I’m happy to report that true fire science has made great strides over the last two decades, and what it has determined is that most of the “rules of thumb” that were the “stock in trade” of fire investigators for decades were wrong.

Here is a short list of what fire investigators firmly, and wrongly, believed for decades were indicative of an intentional fire set with the use of an accelerant:

1)  Burn patterns, or “pour” patterns on the floor.

2)  Spalling of concrete.

3)  “Alligatoring” or “checkering” of wood surfaces.

4)  Crazed glass in windows.

5)  Location and depth of char.

6)  Holes burned in the floor.

7)  Melted or annealed metal.

What was not understood at the time was the phenomenon of “flashover”.  Flashover is when the temperature at the ceiling in a room (with a fire in it) reaches a level sufficient to cause spontaneous combustion of everything in the room.  Once  flashover has occured, all of the above “rules of thumb” are meaningless.  To better understand what flashover is all about, here is a very illuminating video:

Note that it can take just a few minutes to go from a smoldering cigarette to flashover.

It wasn’t until the early 1990’s that science began understanding the phenomenon of flashover.  And it wasn’t until 1992 when the (US) National Fire Protection Association (NFPA) published the first edition of its standard for fire investigation based upon scientific principles, NFPA 921: Guide for Fire and Explosion Investigations.  At publication, the guide was embraced and adopted by the UK, but the reaction of the US fire inspection community was “wailing and moaning and gnashing of teeth”.  Old-line fire inspectors resisted this mightily, and it has taken years for “921” to become generally accepted as the authoritative document, but it has happened.

However, despite the strides made by fire science, problems linger.  In 2005, Steve Carman, Senior Special Agent ATF, helped design and conduct an experiment to judge the ability of experienced fire investigators to determine the location of origin of a fire.  A test room was set on fire and allowed to burn for 7 minutes.  53 experienced fire investigators (who did not observe the fire) from both the public and private sectors were tasked with determining in which quadrant of the room the fire started.  The results follow:

So you can see, we’re not completely “there” yet in the world of fire science.  Steve Carman, has since retired from ATF, and now has his own fire investigation service, Carman and Associates in Sacramento, CA.

Now let me wax “editorial” a bit.  I have no data, and this is speculation on my part, but I would venture a guess that “folklore fire science” has been responsible for more wrongful executions than any other area of forensics.  You may have heard of Cameron Todd Willingham.  “Todd” was convicted and subsequently executed for setting a fire that killed his three children in Corsicana, TX in 1991.  He proclaimed his innocence to the end, and a post-execution investigation by renowned fire scientists, among them Dr. Gerald Hurst, determined that the fire was not arson.  The state of Texas has refused to just come right out and admit they executed an innocent man.  I have recently been involved in an arson death penalty case here in Ohio in which the conviction was based upon the testimony of a fire investigator who’d had a total of 6 days of training.  My study of the evidence convinces me the defendant is innocent, and by the way, he’s been in prison for 21 years (so far), and his execution is pending.

I’m hopeful that the past and continuing advances of science will prevent further miscarriages of justice in future, but there are still lots of cases out there in which junk fire science has wrongfully imprisoned people, and in more than a few cases, sentenced them to death.

Here is some reference material for you:

1)  John Lentini is a preeminent US fire scientist, and with his permission, here is his paper titled “The Mythology Of Arson Investigation”:

Mythology_Arson_Investigation_07 copy

John can be reached at:

John Lentini, CFI, D-ABC
Scientific Fire Analysis, LLC
32836 Bimini Lane
Big Pine Key, FL  33043

2)  Also by John Lentini, and co-authored with Barry Scheck, co-founder of the Innocence Project is a presentation titled “Post Conviction Strategies in Arson Cases”.  This is best consumed along with a presenter’s narrative, but there is a wealth of information in here (it’s a big file):

PC_Strategies copy

3)  Here is a presentation from the Arson Research Project that deals specifically with burn pattern analysis in post-flashover fires:

Live Burn Report

Phil Locke

18 responses to “Arson Investigation – After Decades of Junk Science

  1. Phil,

    Thank you for this helpful update and resource on the evolution of our understanding of the signs of arson. I recall a noted expert suggesting that 200 cases of arson conviction in Texas alone should be reviewed in light of current thinking. Now that there is recognition that the expert testimony used in the past was incorrect, has there been any suggestion that there be a systematic review of cases that depended on this flawed forensic testimony?

    Nancy Petro

  2. Nancy,

    Thanks for your comment. I am not aware of any programs in place, or anticipated, to review questionable convictions. And the state of Texas, in particular, has dug in it’s heels, and is resisting this – case in point, the Willingham case. As far as I know, cases are still being tackled individually once they catch somebody’s attention.


  3. For a brief period, thanks to the late JEHT Foundation (obliterated by Bernie Madoff) we had funding to run an Arson Screening Project at John Jay College’s Center for Modern Forensic Practice. The idea was to have a central node where at least a preliminary review of the fire-science used at trial could take place. We enlisted very accomplished forensic science graduate students, without the credentials of a (say) John Lentini who you would want for trial testimony but very capable of doing the work. The Project terminated prematurely, but it ran long enough to make me a little skeptical about trying to provide a remote vehicle for these assessments detached from the trial level people, documents, etc. Better than nothing—and now there’s nothing—but can’t claim that we proved the concept positively. Certainly helped to prove the NEED for something to answer this problem, though.

  4. I’m one of the people that spent time in prison for something I didn’t do, burning my own house down!! I didn’t know that my ‘trial attorney’ had a contract with the city that charged me with ‘Arson’ as their ‘union defence attorney’ for THE FIRE AND POLICE DEPARTMENT!! Even though the tests were negative for a ‘fuel substance on the floor the ‘prosecutor AND… the out of date fire inspector CLAIMED all of the ‘evidence burnt up in the fire!! Well I NEVER COULD FIGURE OUT… IF ALL OF THE ‘EVIDENCE’ BURNT UP IN THE FIRE…WHAT was I doing IN COURT!?!? I apeald my conviction not once BUT MANY TIME’S AND…. even though I had TWO fire investigator’s that DID’NT know each other BUT were from two different part’s of the Country agreed that the fire WAS’NT ARSON the Court’s REFUSED to hear WHAT they had to say!! One of the fire investigator’s that said this was’nt Arson actually WAS available to ‘testify at my trial BUT my trial attorney DID’NT present ANY DEFENC witnesses!! Maybe it had something to do wit his contract with the city as their union defence attorney for….. the fire and police!! After my personal ‘experience’ ‘ I’ve always thought that ‘Fire department’s should have ‘Investigation board’s’ sort of like the police department’s with ‘internal affairs. The reason that I say this is… when a fire investigator makes a ‘MISTAKE’ there is NO ONE for them to be held accountable to…. it’s… just a mistake…. no matter the cost to the public!! In my case I ended up spending 2 year’s in prison for something that i DIDNT WILLFULLY,INTENTIONALLY,KNOWINGLY CAUSE!! I left my then 11yo. Daughter which spent most of the next two year’s with my husband which turned to alcohol for comfort leaving my daughter to raise herself for the two year’s I was taken from her!! I also had a grand son that was born while I was in prison which only lived for 17 day’s….he died before that we EVER got to meet. I guess that I’m writing a commentary here because ‘FIRE INVESTIGATION’ needs some SERIOUS CHANGE so little girl’s DON’T LOOSE THEIR mommy’s by WRONGFUL CONVICTION’S AND Grand-mother’s don’t get CHEATED out of what COULD be THE ONLY TIME that they may see their grand baby’s!! I know that the investigation at my house was’nt correct!! I can only HOPE for change to better this subject of Arson ‘fire science!! Even though I was Wrongfully convicted AND some are’nt so fortunate with this subject matter… I ALWAY’S felt fortunate that the Very people who were SUPPOSED to PROTECT ME ‘FIRE AND POLICE’ I ALWAY’S felt fortunate that they at least did’nt ACCUSE me of something that they could take my life for!! No one is Imune from this happening to them!! I used to believe this was ONLY something that you saw on Lifetime that was…. until I happened TO me!!

    Wrongfully convicted in Ohio

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  12. Thank you for the good work you’re doing!

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