Arson Science Rewritten 152
An anonymous reader handed us a link to an AP story about advances in the science of arson investigation. Many assumptions about fire, long held by investigators, have been overturned in recent years as scientists have come to understand concepts like 'flashover'. The repercussions of these findings is having an effect not unlike the use of DNA in crime-solving; people are being set free, and old cases are being re-examined. From the article: "Significantly, flashover can create very hot and very fast-moving fires. And it can occur within just a few minutes, dashing the concept that only arson fires fueled by accelerants can quickly rage out of control. The studies began to chip away at the old beliefs -- critics call them myths -- but it took years. Through the 1980s, texts at the National Fire Academy in Emmitsburg, Md., still taught the traditional techniques. It wasn't until 1992, when a guide to fire investigations by the National Fire Protection Association -- 'NFPA921: Guide for Fire and Explosion Investigations' -- clearly laid out, in a document relied upon by authorities nationwide, that the earlier beliefs were wrong."
But the prosecutors were so CERTAIN I was guilty! (Score:3, Interesting)
-signed, dead guy who was obviously guilty
Re:Hmmm, Not in my training and experience (Score:4, Interesting)
lots of junk science in police work (Score:4, Interesting)
After something like 40 years of this being accepted, someone actually tested it. Result: no freaking correlation at all. The variation in composition of bullets within a given box was the same as variation among bullets from different boxes, purchased years apart. This is a completely worthless forensic technique.
Or consider early DNA testing. Up until at least the mid '90s (I don't know what they do now) a DNA test only looked for matches at a small number of base pairs. For any given DNA sample tested, there would be thousands of people in the world that matches that sample. What this meant was the the scientifically correct way to use DNA testing was to find your suspects using traditional police techniques, and THEN use a DNA test. If you had, say, 3 good suspects, and one of them had a DNA match, then that was very good evidence against that suspect. Unfortunately, sometimes it was used the other way. They'd start with the DNA, match it against whatever samples they had on file, and if they got a match, they'd go after that person. That's bogus.
If you look into the science behind much police investigation, you get this strange feeling you've fallen through some kind of wormhole and gone back to the early 19th century. It's amazing how much in common use has not been rigorously tested and peer reviewed by real scientists.
Fire investigation (Score:3, Interesting)
What is probably the single most annoying thing about fire investigation- from the investigator's perspective- is that arson is a terribly difficult crime to prove. Without a witness or some form of photographic or video evidence where an individual physically lights something on fire, the crime of arson is difficult to prove. As an instructor long ago put it to us: A man walks into a structure, and then walks back out. Later, it catches on fire. Houses burn all the time- bad wiring, gasoline stored near a gas water heater, cigarettes left burning. But causality- that that fire was intentionally set, and was set by that individual- may be difficult to prove.
In that regard, arson can be more difficult to prove than murder. With murder, there is frequently trace evidence with everything from blood droplets to weapons used, that can associate the murderer with the crime. With arson, in many cases there is heavy fire, smoke, and water damage, as well as the difficulty in proving that a fire started intentionally versus accidentally. Trace evidence such as gasoline found on the shoes of the accused arsonist can often be explained by more mundane events, such as spills at a filling station.
Making things worse, the folks who investigate are often poorly- or incorrectly- trained, and sometimes don't even want the job. Things are changing and candidates are frequently better educated than they have been in the past, but it's still a little rough around the edges. There aren't too many investigators in the field with advanced degrees, and a week or two of schooling (Arson I and II) at a state fire academy or the National Fire Academy are considered enough to get to work in many cases. 40 hours of fire investigation training, and you can help in putting people behind bars for what is considered a heinous crime such as arson of a habitable structure.
Sometimes investigation doesn't even start with the fire itself. Financial records are often scrutinized to determine if the accused would benefit financially. Business not doing well? Maybe it was torched. Home being remodeled? Maybe a convenient excuse to collect on insurance because of some major construction issues that existed. Upside down in your auto loan and gas hit $3 a gallon? That Yukon sure burns good!
Put all these together, and it's little wonder that some of the folks accused and convicted of this sort of thing are convicted and jailed. Many are poor, and get lousy lawyers- juries are likely to convict on scant evidence when the alternative is to let a possible firebug out on the streets.
Fortunately, there are improvements, and the standards for training have gone way the heck up in past years. Certification under some standard for training is often required for the job, as well as continuing education to stay on the job. Engineers, chemists, modelers, and physicists tackle some of the more difficult issues with lab tests to back up what's being said in court. It's one thing to say that a steam pipe at X degrees for Y years can eventually cause enough pyrolysis of nearby wood to create open flame; it's another to have some PhD back it up with experiments that prove it, possibly exonerating the accused.
Sometimes folks believe strange things from way the heck back in their training. This is part of the legend behind "spontaneous human combustion." The '921 says in it somewhere in a straightforward (and vaguely comforting) manner that humans do not spontaneously combust. Now only if we can do that with the other bits of legend that investigators have clung to over the ages.
Re:Hmmm, Not in my training and experience (Score:3, Interesting)
Investigations (Score:2, Interesting)
As was said earlier, it's damn near impossible to get an arrest for arson, much less a conviction. We had a guy admit to trying to torch his car for the insurance. He even wrote a confession and signed it, in front of my father and sheriff's deputies, and the DA let him off.
Arson investigation is grueling, filthy work. Hours on hours of rooting around in the rubble that was someone's home or business; sorting out the evidence from the disaster.
Fellow nerds, even though this shows that fire investigation is still an evolving science, go thank a firefighter or investigator for their service anyway. It'll make their day.
The Bradford Stadium Fire (Score:4, Interesting)
Re:Wooden houses? (Score:4, Interesting)
Wood is a very common material in residential construction in Germany, and in fact its usage has increased with the larger number of prebuilt houses being built here.
Re:Hmmm, Not in my training and experience (Score:3, Interesting)
items and conditions found at the scene is what proves your case in court, but it isn't what finds you your suspect, that's done from "Good 'ol police work" knowing what to ask, and who to ask it from, and a large helping of intuition.
In each of the cases I was involved in the police already "knew" who did it, they just needed to prove it. most of that was done through undercover operations, where police officers would befriend the suspect and get them to tell all, even brag about the event. from there people were sent to confirm the details the suspect gave. One of the cases they had a huge search around the area where the victim was last seen, people combing the ditches and a helicopter circling overhead and with every news outlet on hand covering it, sure they wanted to know if any clues were found, but mainly they wanted the suspect to see it on the news, panic and do something stupid.
The hunches may not be scientific, but the police don't take a hunch to court, and even a confession from the suspect is not usually enough as the suspect can always tell the court "I signed that under duress!" (and once they get a decent lawyer they probably will!) the police have to narrow it down from "the whole world" to a handfull of suspects somehow, and that's usually not completely scientific, but from there proper procedures take over and you have to prove everything. On a side note, investigators HATE CSI etc, not because of how inaccurate it is, they could care less about that, what they hate is that the general population, and hence most juries, think it's true. It makes proving things much harder because people won't accept evidence that isn't what they expect from CSI... (you can have pictures, video, witnesses, tire tracks, admission of guilt, matching weapons, but if you don't have DNA forget it! and those labs are backed up MONTHS.)