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Techniques used in arson case now seen as outdated

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  • Techniques used in arson case now seen as outdated

    October 26:

    I find this interesting, especially since seventeen years later — and five years after Willingham was executed in connection with the case — nine fire experts have raised the possibility that the blaze may have indeed been accidental, citing revised standards in arson investigations.

    The arson investigation into the Willingham case was conducted before the 1992 publication of what has since become the standard for arson science: NFPA 921, a Guide to Fire and Explosion Investigation, published by the National Fire Protection Association. Vasquez and Douglas Fogg, then assistant fire chief for Corsicana, cited more than 20 indicators to conclude that the fire was intentionally set. But several of those indicators have since come under question in light of the newer standards in NFPA 921.

    1. "Crazed glass," a weblike pattern earlier assumed to be caused by use of a liquid accelerant. Now it is also attributed to the rapid chilling of hot glass by water from fire hoses.

    2. "Pour patterns," "trailers" and "puddles," markings suggesting that someone dumped accelerant. A "post-flashover fire" — which spread from single objects to engulf an entire room, reaching temperatures of more than 2,000 degrees — can also produce floor burn patterns that cannot be distinguished from those caused by liquid accelerants.

    3. Multiple points of origin, which can indicate that a fire was deliberately ignited. But other causes, such as embers or drop-down burning, can produce the same effect, experts said.

    full story and photos here;

    http://www.star-telegram.com/600/story/1710031.html
    "Take care of yourself first. Life is too short and you never know what tomorrow or for that matter...what the next few seconds is going to bring."

  • #2
    1OLDTIMER-

    I would like to get your thoughts on some issues relating to a local fire accident. Please email me your email address at [email protected]. I will then email you my contact information.

    Comment


    • #3
      The change in significance and interpretation of some fire indicators is due to a better scientific understatement in fire dynamics and in the way materials are affected by.
      NFPA 921 suggest a truly scientific approach to fire investigation and warns against use of anedoctal facts as a reliable source of information.

      Comment


      • #4
        Originally posted by 1OLDTIMER View Post
        October 26:

        I find this interesting, especially since seventeen years later — and five years after Willingham was executed in connection with the case — nine fire experts have raised the possibility that the blaze may have indeed been accidental, citing revised standards in arson investigations.

        The arson investigation into the Willingham case was conducted before the 1992 publication of what has since become the standard for arson science: NFPA 921, a Guide to Fire and Explosion Investigation, published by the National Fire Protection Association. Vasquez and Douglas Fogg, then assistant fire chief for Corsicana, cited more than 20 indicators to conclude that the fire was intentionally set. But several of those indicators have since come under question in light of the newer standards in NFPA 921.

        1. "Crazed glass," a weblike pattern earlier assumed to be caused by use of a liquid accelerant. Now it is also attributed to the rapid chilling of hot glass by water from fire hoses.

        2. "Pour patterns," "trailers" and "puddles," markings suggesting that someone dumped accelerant. A "post-flashover fire" — which spread from single objects to engulf an entire room, reaching temperatures of more than 2,000 degrees — can also produce floor burn patterns that cannot be distinguished from those caused by liquid accelerants.

        3. Multiple points of origin, which can indicate that a fire was deliberately ignited. But other causes, such as embers or drop-down burning, can produce the same effect, experts said.

        full story and photos here;

        http://www.star-telegram.com/600/story/1710031.html
        one way to tell if its a pour pattern is to take that piece of material and send it to get tested in the lab. Also this case was filled with Negative Corps---

        Comment


        • #5
          Originally posted by fvfdstation4 View Post
          one way to tell if its a pour pattern is to take that piece of material and send it to get tested in the lab. Also this case was filled with Negative Corps---
          May I suggest you that this is not enough? Any organic/plastic and even wood product that pyrolize during a fire can develop many molecules that closely resemble those found in petroleoum products or can even be made using organic glue or lacquers that are made by petroleoum products, this will cause a false positive, so it is mandatory to perform the same analysis on a similar sample from any place outside the apparent pour pattern.
          Otherwise any trace of accelerant could be questioned.

          Comment


          • #6
            Same thing as death. 100 years ago someone gets dug up and they thought it was a vampire. Now, it's called thanatochemistry.

            Comment


            • #7
              Slow down guys.

              Couple of thoughts:

              1. For every true pour pattern I find, I can show you an equal number of uneven floor fire patterns that have been caused by completely innocent means. It is a fatal error to judge a fire pattern as having been caused by a liquid accelerant absent a lab confirmation.

              2. There is no such thing as a false positive. If the lab report comes back saying there is a substance consistent with a liquid accelerant present, that is a positive.

              3. The challenge with a positive lab hit is to discern whether that positive is a result of a hostile intentional act, an accidental occurence or a natural phenomenon. This is done through a good thorough scene examination, solid interviews, a fire scene reconstruction and a common sense analysis of the data. Even if there is a positive hit for gasoline, a good investigator will always consider the possibility that the gasoline belonged at that spot. For example, kids huffing from a container of gasoline in a bedroom. Gasoline spills and ignites due to a candle flame. Positive hit, but not an incendiary fire.

              4. An investigator must be extremely careful with "comparison samples" (they are not "control samples". You must make sure that the materials taken for comparison are of the same matrix and are uncontaminated. The best way to do this is to take the samples from a hidden area. The worst thing that could happen is to have your comparison samples come back positive also. It is reality that you will not be able to find reliable comparison samples at every fire.

              5. Professional fire investigators today do not investigate fires by using artifacts as indicators. Todays investigators, at least the one's doing it correctly, conduct a total investigation, with areas of origin based on four things; witness observations, fire pattern analysis, fire science application and arc mapping. Calls as to the cause of a fire are based on positive evidence developed during the investigation and cite three things; first fuel ignited, source of heat energy and the ignition factor (what brought the heat and fuel together). Anything less is an undetermined fire.
              PROUD, HONORED AND HUMBLED RECIPIENT OF THE PURPLE HYDRANT AWARD - 10/2007.

              Comment


              • #8
                English is not my native language so I do not understand if false positive means what I intended to say: clearly a lab test can just say what is in that sample, so if it says hydrocarbons then is positive to hydrocarbon, but this does not mean that is a positive detection of a accelerant pour pattern or if the spill was intentional.
                Control sample can exist only in an experiment, not in a real event, so the distinction between control and comparison is an important clarification.
                I agree with George on all of its remark, but based on my experience I am quite skeptical on the availability of reliable witness observation.
                Giovanni

                Comment


                • #9
                  Originally posted by Giovanni012 View Post
                  English is not my native language so I do not understand if false positive means what I intended to say: clearly a lab test can just say what is in that sample, so if it says hydrocarbons then is positive to hydrocarbon, but this does not mean that is a positive detection of a accelerant pour pattern or if the spill was intentional.
                  Control sample can exist only in an experiment, not in a real event, so the distinction between control and comparison is an important clarification.
                  I agree with George on all of its remark, but based on my experience I am quite skeptical on the availability of reliable witness observation.
                  Giovanni
                  Witness observations are one of the four items that are cited on NFPA 921 on which an investigator bases his origin determination. They are not the only one. A witness's observations are data' data that needs to be collected. If the observations are later found to invalid (based on correlation with the other data collected) they need not be considered. I personally find trained witness observations quite reliable. I will rely heavily on the observations of the first due incident commander and the first fire fighters in the building.
                  PROUD, HONORED AND HUMBLED RECIPIENT OF THE PURPLE HYDRANT AWARD - 10/2007.

                  Comment


                  • #10
                    Yes NFPA 921 says that and I have adopted that code as my guideline, but I have to consider two facts:
                    1) In my country ( and especially in the fires that is see most) any interior attack is seldom done and FF arrives that the building is close to full involvment, so many precious information on the fire seat are lost or not available
                    2) I work in the private sector and not always I am allowed to interview the FFs and the IC. This depends on many different factors, but is closely related to the different law system.
                    Beside that when there are witness observations they are one of the element that plays a role in the investigation.
                    One another important source of infos are TVCC and safety cameras, but I recently had a fire ( with few witness) where the clock of the TVCC was some hours wrong!!!
                    This at first was really misleading but finally we were able to figure out this and recolletting the observations of first responders we were able to draw a timeline of the event.
                    Giovanni

                    Comment

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