Three forensics questions.
1. Does anyone have an approximate number of how many different models of semi-auto pistols have been chambered in 9mm Parabellum?
2. Can a crime lab ID the make and model of a semi-auto pistol that fired a cartridge if all they have to study is a spent casing?
3. How well does the test for powder residue work? How long after a shooting can it be done and does washing one's hands defeat the test?
2. Can a crime lab ID the make and model of a semi-auto pistol that fired a cartridge if all they have to study is a spent casing?
3. How well does the test for powder residue work? How long after a shooting can it be done and does washing one's hands defeat the test?
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1) Very many.
2) No.
3) Washing thoroughly defeats it. If unwashed, it can reasonably be detected for 48 hours+
Was this a test ??
Doug0 -
Dont do it!! 0 -
Go ahead !!
I promise not to get mad !!
Doug0 -
quote:Originally posted by mateomasfeo
Dont do it!!
But couldn't you use the business?0 -
1. 645 (guesstimate)
2. yes, and if they can get the maufacturer to cooperate, they can even get the serial number if they keep the test bullets (provided they don't change the barrels before shipping)
3. washing (hands, shower, clothes etc.) will eliminate gsr.
i love watching NCIS. abbey rules.0 -
Sounds like our resident PhD has something on his mind......
I will keep checking the headline in the LR paper and report it to the board when the story runs, as our resident PhD will probably be away from his computer for 15-20 years until he gets paroled.0 -
Who you gonna shoot? 0 -
quote:Originally posted by mateomasfeo
Dont do it!!
[:D][:D][:D] My thoughts exactly!0 -
quote:Originally posted by aramisvi
1. 645 (guesstimate)
2. yes, and if they can get the maufacturer to cooperate, they can even get the serial number if they keep the test bullets (provided they don't change the barrels before shipping)
3. washing (hands, shower, clothes etc.) will eliminate gsr.
i love watching NCIS. abbey rules.
That she does!0 -
Would forensics be able to tell a spent 30-06 bullet from say a 7.62x54R or .308? 0 -
Just what exactly do you need that info for Saxon.
If you need a witness to prove you didn't do it, I am your man.[;)][:D]0 -
(1) Enough that I'd not venture even a WAG.
(2) Maybe. Attended a real-world (not CSI-TV) ammunition forensics seminar in which this topic was discussed. There are several potential sites on a fired case which can provide clues (14(?) something like that - I was amazed) where the casing comes into contact with the action with enough force to leave marks, however microscopic. Anyway, some of those markings are characteristic of certain firearm designs, such as the square firing pin slot image on the primer cup of a round fired in a Glock. Location / angle of extractor scratches is another item. Then there are characteristics unique (theoretically) to individual firearms such as the patterns imparted by the firing pin. The point was that the forensics guys can pretty well confirm / deny a casing came from a particular firearm *if* they have *both* to examine, but with the casing alone "it depends."
(3) A good scrub will defeat it. Fertilizing a garden in front of witnesses makes a positive result suspect because of the nitrates in the fertilizer. Probably there are other legitimate sources of nitrate residues as well. With all the advances in technology - amount of sample needed, precision of instrumentation, etc., my WAG is that these sorts of tests will become more definitive as the technology evolves - discriminating between the sorts of nitrates, for example.
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Is POOF about to take on a whole new meaning around here?[:D] 0 -
1. Hundreds, if not more, if you count model variations and clones
2. To my understanding, it can identify ejection characteristics. As for ID'ing a particular make and model, I don't think so. If you have a specimen to compare it to, an expert can provide an OPINION on whether it matches the gun that fired the one he examined, but this is hardly an exact science.
3. It works pretty well, if not vigorously and thoroughly washed with strong soap more than once. Also, it can be other places besides just your hands. Think wrists, forearms, your shirt/jacket. Time dissipates it and after a few days it should be pretty much non-existent.0 -
Even if a fired case could ID the particular pistol, it seems to me that anyone with any sense that uses the firearm for nefarious purposes, would disassemble the weapon and chuck the separate parts in scattered bodies of water, or bury them.
What are you trying to get at with the "how many" question. Certainly more than it is practical to keep a database of indentifying characteristics for each one.
If you plan to need to blast someone, use a 12 guage with #4 shot, and get rid of the firearm.0 -
[:D][:D][:D][:D]Funny questions! 0 -
Number #2 can be done, but usually it is used to ID the case as having came from a particular known firearm.
The History Channel recently did a study of the spent cartridges found at the Little Big Horn battle sight. They could ID what type of guns were used, and in some case having rifles used in the battle by various known participants they were able to ID the locations of were the person was firing from.
Trinity +++0 -
I watch shows such as "Forensic Files,", and they have ballistic experts who claim they can match a fired bullet, or case, to a particular gun.
I find this hard to believe.
Let us say you had twenty brand new Beretta 92F pistols, and you have one fired bullet and case. Are you telling me they could positively id the pistol that was used? I don't believe it.
I can see that they could prove that the gun was a Beretta, and not a Smith and Wesson. But that they could differentiate among twenty identical Berettas? I don't believe it.
These forensic guys are not always to be trusted. For years, the supposedly preeminent forensic lab, the FBI lab, had a method of getting an id on bullets, by the metallurgy. They would analyze the content of the fired slug, besides lead there could have been 3 or 4 other metals in trace amounts in the bullet. Then, the FBI would get a box of cartridges from the suspect's house and analyze the metal in those slugs.
The FBI claimed that they could match the bullet to that box of ammo, in that that box, and all the othere boxes that were made in that same batch by the manufacturer, all had identical trace minerals. That makes sense, but the FBI claimed that another batch made on a different day, or by a different manufacturer, would have different trace minerals. The FBI got several convictions by using slug metallurgy analysis.
Some wily defense attorneys recently got some metallurgists of their own, and proved that the FBI's science was all wrong and that this was not a reliable way to id bullets. A couple of cases got overturned, and as I understand it the FBI is not using this type of bullet id any more. As for the guys who got false convictions by bad FBI lab work, tough luck.0 -
My wife, the law school student, is partricupating in moot court this week and the case involves a murder where an unknown 9mm handgun was used. She was looking for some info on how many suspect guns there might be (all I could tell her was that hundreds and hundreds of models in that caliber have been made), if the murder weapon make and model could be IDed from only a shell casing, and how long a test for powder residue could be administered.
If I were plotting a murder I certainly wouldn't talk about.
And I don't have a Ph.D.0 -
Well , are trying to plan a criminal act , or trying to find a way out of one ???
answers : #1 more than we can reasonably name ...
#2 Yes , they can tell what gun fired the case ...
#3 No , generally speaking , washing will Not ...
I would say Good Luck , but I'm not sure that it would be in order ?
Thanks !!!
d.a.stearns
Gunsmith / LEO
Niota , Tn0 -
Maryland thinks #2 is possible because we are required to supply a spent casing (sealed from the manufacturer) with each new gun we purchase. I think MD is the only state the requires this. 0 -
Saxton... I suggest you use a ruger convertable..... Bullets will be lightly engraved throwing off ID of the bullet..... no cases to be found, but you could toss out a few "range " pickups to really screw things up.
Powder residue.... some of us shoot nearly every day and will likely always have some residue on us. When you finish the deed go out shooting, with another gun, for a while to ensure that you have more residue on you than could possibly achieved from one or two shots.
[:0]Did I just say all that stuff out loud???????[:D]
While one should not underestimate forensic technology what we see on TV is often not a reasistic characterization of current capabilities. Some of the conclusions they come to are "leaps of faith" longer than the Grand Canyon is wide.0 -
slipgate,
NY State also requires a spent cartridge on all handguns to be sent to the State Police.
2 is a yes, and like finger prints, no two firing pins can leave the same identical markings when put under microscopic scrutiny. The spent bullet can be matched to a gun because of the marks that the barrels lands & groves leave on the projectile. No two barrels leave the exact same marks.
Trinity +++0 -
1911 .45 pistol.
Old, shot-out, worn-out, pitted-out, GI barrel.
Brass catcher.
Barrel goes, in pieces, into a deep lake when done.0 -
Pistols are suppose to leave some kind of tracable firing pin indentation on a spent case. Don't know either if the spent case can have a fingerprint taken off of it. I've been watchint too much CSI 0 -
What disturbs me is that apparently many here have given this quite a bit of thought. [:0] 0 -
What if someones elses spent casings were at the scene from their gun not the one who did the crime. 0 -
select-fire,
I am sure it has happened, but to connect the two you have to have a firearm under suspicion. The wrong case may send you off in the wrong direction, even if it's the same caliber, but you will most likely never find out which gun it was fired from without first having the gun you suspect it was fired from.
I know of no crime having been solved from all the spent cartridges that are being sent into various State crime labs. It is too much of a needle in a hay stack situation.
Trinity +++0 -
To reiterate:
1) Every one pretty much agrees that, at least, hundreds of 9MM firearms have been produced, since the introduction of the round in, what, 1909. Don't forget long guns and those little steel inserts for shotguns.
2) No one has a difinitive answer. So, that being the case, assume that Nunn's advice was/should be used.
3) GSR tests only really count if done immediately after the shooting, and before the shooter has a chance to change/wash clothes and shower.
If I were to plan a killing, I'd purchase a weapon on the street, use it once, and dispose of it. I would try to pick one that would leave ambiguous indicators.
Let us know, please, if we provided anything useful.
Hope for the best - plan(and expect) the worst.
It's much simpler to just get a divorce. You can't spend the money you would save with this method, if you are behind bars.
Good luck.
Doug0 -
quote:Originally posted by TrinityScrimshaw
I know of no crime having been solved from all the spent cartridges that are being sent into various State crime labs. It is too much of a needle in a hay stack situation.
Trinity +++
That was a major part of the case that sent Leonard Pelteir to prison for being (wrongfully) accused of murdering 2 FBI agents on Pine Ridge Rez in the 1970's0
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