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Fingerprints Recoverable From Cleaned Metal

Posted by Soulskill on from the leaving-a-mark dept.

dstates points out a recent article from guardian.co.uk which discusses a new method by which to recover fingerprints from metal. The method relies on corrosion caused by sweat and other biological residues on the metal's surface. Quoting: "The patterns of corrosion remain even after the surface has been cleaned, heated to 600C or even painted over. This means that traces of fingerprints stay on the metal long after the residue from a person's finger has gone. The chemical basis of the change is not yet clear, but [Dr. John Bond] believes it is corrosion by chloride ions from the salt in sweat. These produce lines of corrosion along the ridges of the fingerprint residue. When the metal is heated, for example in a bomb blast or when a gun is fired, the chemical reaction actually speeds up and makes the corrosion more pronounced."

39 of 178 comments (clear)

  1. Plastic weapons by Anonymous Coward · · Score: 2, Insightful

    This will open up the renaissance of plastic weapons.

    1. Re:Plastic weapons by shadow349 · · Score: 5, Insightful

      This will open up the renaissance of plastic weapons.
      Or, you know, gloves.
    2. Re:Plastic weapons by mabhatter654 · · Score: 2, Insightful

      it would seem to be only circumstantial evidence though.. nearly every person who fired the gun would leave a "permanent" fingerprint. That would reduce the utility of this. I suppose what they're after is damaged metals though. Like from bombs or car crashes during persuit to be able to figure out who the guy working on the metal was when he's cinders.

    3. Re:Plastic weapons by nospam007 · · Score: 2, Insightful

      Or perhaps it will cause criminals to start taking better care of their guns. A well oiled gun won't have this problem.

      Or use stainless steel guns.

      I guess the most impact could be if they could check guns from unsolved crimes from the last 50 years, if no dumbwit copa handled them without gloves that is.

  2. Damnit! by jawtheshark · · Score: 3, Funny

    Damnit! I knew I should have used plastic vats to hide the bodies!

    --
    Ahhh...the great dumpster continuum. Many a free computer will be found there. -- sowth (748135)
    1. Re:Damnit! by txoof · · Score: 3, Funny

      Yeah, using hydrofluoric acid in the bathtub is a BAD IDEA (tm).

      There's a great Scene in Breaking Bad where Jessee tries to dispose of a body in a tub using hydrofluoric acid and a disgusting cheese body gloop falls through the ceiling after the HF eats the tub.

      --
      This one's tricky. You have to use imaginary numbers, like eleventeen... --Hobbes
  3. I wonder by oodaloop · · Score: 4, Interesting

    how many peices of evidence for earlier crimes we can now find a print where we couldn't before? Maybe solve an unsolved crime or two, or free someone innocent? The ramifications for Iraq alone where we can match prints on IED remnants to current detainees is enough to keep me interested.

    --
    Tic-Tac-Toe, Global Thermonuclear War, and relationships all have the same winning move.
    1. Re:I wonder by txoof · · Score: 5, Insightful

      That's a really good question; it could be a huge boon for unsolved cases, vindicating wrongfully convicted individuals. I could also be a huge disaster for police departments. Thousands upon thousands of individuals appealing for reexamination of fingerprint evidence could swamp crime labs.

      That being said, it is far worse to convict an innocent individual than to let a guilty man go free.

      --
      This one's tricky. You have to use imaginary numbers, like eleventeen... --Hobbes
    2. Re:I wonder by Ucklak · · Score: 2, Interesting

      Except now we're all going to be fingerprinted so they can match these rogue fingerprints.

      --
      if you steal from one source, that is plagiarism, if you steal from many, well, that's just research.
    3. Re:I wonder by Vellmont · · Score: 4, Insightful


      how many peices of evidence for earlier crimes we can now find a print where we couldn't before?

      How many pieces of evidence are now ruined, because there wasn't a careful procedure followed in the chain of evidence where nobody touched it? A bullet casing or bomb fragment being criss-crossed with fingerprints isn't exactly going to make this technique any easier.

      --
      AccountKiller
    4. Re:I wonder by cluckshot · · Score: 5, Insightful

      This really drives one to another issue. The longevity of the fingerprints will remove their value. All a finger print proves is proximity. As long as a finger print is there, it proves nothing but attendance. If it was a bio-subtance it had a short life span making it not only presence in definition but also proximity in time. That made finger prints useful. The problem here is that these now become "Undated" finger prints and as such unable to be related to events which was their only value in crime ID other than to have a list of suspects. This points out the most amazing reality about the crime "proof" we see in labs today. For the most part science is destroying evidence entirely. For example: Photos once were valuable. Then retouching started. Then it went to digital where retouching could be infinite. In the end, a photo is little more than fiction in court. Sound prints same. Now we see the ability of the police to fabricate evidence against someone to fullest extent unless we all are aware of what can be done.

      --
      Never Politically Correct ~ I prefer the facts If you don't like what I say, get a life, or comment yourself.
    5. Re:I wonder by couchslug · · Score: 2, Insightful

      "That being said, it is far worse to convict an innocent individual than to let a guilty man go free."

      At a one/one ratio, but some friendly casualties are inevitable. We accept a certain baseline of victims and injured/KIA police as the cost of fighting crime. We also tacitly accept a few wrongful convictions...

      --
      "This post is an artistic work of fiction and falsehood. Only a fool would take anything posted here as fact."
    6. Re:I wonder by mikael · · Score: 5, Interesting

      Just imagine all the suspects involved with fingerprints on the brass cartridges:

      1. The packing person who took the cartridges and placed them in a cardboard box.

      2. The shop owner who took the cartridge out of the box to ensure it was a match with what the customer wanted.

      3. The actual person who loaded the weapon.

      If one fingerprint overwrites another, then it's not a problem. But what if the corrosion effect is additive and you get two patterns merged together. Would forensic experts be able to separate the two or would they get false positives with other fingerprints of innocent people?

      --
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    7. Re:I wonder by muridae · · Score: 3, Interesting

      "That being said, it is far worse to convict an innocent individual than to let a guilty man go free."

      At a one/one ratio, but some friendly casualties are inevitable. We accept a certain baseline of victims and injured/KIA police as the cost of fighting crime. We also tacitly accept a few wrongful convictions...

      When does the ratio become acceptable or unacceptable? At 10:1; 1:1; 1:1,000,000 or at either extreme, "Even the innocent should be jailed if it means we catch all the guilty people." or "The guilty should go free rather then an innocent person be jailed."
    8. Re:I wonder by Dorceon · · Score: 3, Insightful

      Of course the ability to find old fingerprints doesn't mean it's no longer possible to dust for prints the traditional way. You know, the way that does prove proximity in time?

      --
      What sound do people on rollercoasters make? Hint: it's not Xbox 360.
    9. Re:I wonder by Digital+End · · Score: 2, Insightful

      That being said, it is far worse to convict an innocent individual than to let a guilty man go free.


      Tell that to the next rape victom.

      Life isn't black and white, I loath short high and mighty quotes that try to paint it that way.
      --
      Beware of he who would deny you access to information, for in his heart, he dreams himself your master.
    10. Re:I wonder by cos(0) · · Score: 4, Informative

      This question was raised and discussed by Alexander Volokh in n Guilty Men.

    11. Re:I wonder by __aajfby9338 · · Score: 5, Informative

      Even though it's wrong target, you can still trace back to see to whom shop owner sold those cartridges.

      Cartridges are not serialized. Even lot numbers are just marked on the carton, not on the cartridge, and any given production lot can end up being split between many, many sellers. With a shelf life measured in decades, a box of ammo might sit around on the shelf for a long, long time, and may change hands many, many times before being used. It's not even that unusual to use surplus ammo dating back to WW2 or before. A brass cartridge might have the year of manufacture stamped on the head (more likely for military ammo than for civilian ammo), and there are no markings at all applied to the projectile.

      In general, it would be pretty hard to trace an arbitrary cartridge back to a particular seller or buyer without other evidence. About all that you can determine from a shell casing found at the scene of a crime would be the manufacturer, caliber, possibly the original year of manufacture (and that shell casing might have been reloaded numerous times after that), fingerprints of one or more persons who have handled it, and it may be possible to determine that it was fired in a particular firearm if (and only if) that firearm is recovered, and has not been modified, repaired, serviced, upgraded, or even fired a large number of times since that shell casing was fired in it.

      You probably will not be able to trace a cartridge to a buyer or seller unless the box it came out of is also left at the scene with its credit card receipt taped to it, and even then it could be argued that a receipt indicating that particular brand and type of ammo (if the brand and type is even listed on the receipt) didn't correspond to that specific box of ammunition, and/or that the shell casing did not come from that specific box. It would be much like trying to match an individual paper napkin to a particular package, manufacturer, seller and buyer.

      The FBI used to claim to be able to match a bullet to a specific manufacturing lot based on chemical analysis of the bullet's lead, but that technique has since been shown to be bogus.

    12. Re:I wonder by couchslug · · Score: 2, Insightful

      My "feelings" are not relevant to the facts, which I noted above. While it is the duty of law enforcement to try to avoid punishing the wrong people, it is not rational to expect that it will never happen.

      I would be trying everything I could to get any wrongful conviction reversed, but I would still understand that ALL processes have an error rate which, while it can be reduced, cannot always be reduced to zero.

      --
      "This post is an artistic work of fiction and falsehood. Only a fool would take anything posted here as fact."
    13. Re:I wonder by JesseMcDonald · · Score: 3, Insightful

      Perhaps a better question would be: are you willing to take the risk that the person you're locking up may later be proven innocent, knowing that if that happens you'll have to pay restitution for all the pain and suffering you've caused them (not to mention lost wages, etc.)?

      The "correct" balance between false positive vs. false negatives is far too abstract to have any objective answer. This is a situation that calls for a feedback loop, punishment in proportion to the effects of an incorrect judgment. The standard of evidence would then take care of itself. In any event, it is only right that one make up for harm done to others, even when one thought one was doing the right thing at the time.

      --
      "The state is that great fiction by which everyone tries to live at the expense of everyone else." - Bastiat
    14. Re:I wonder by garett_spencley · · Score: 4, Insightful

      "We also tacitly accept a few wrongful convictions..."

      Speak for yourself.

    15. Re:I wonder by keeboo · · Score: 2, Insightful

      but I'd risk an innocent to keep in a rapist/murderer

      Try stating that once you're the innocent in question.

    16. Re:I wonder by Headw1nd · · Score: 5, Insightful
      I'll bite, because we don't need lofty quotes to prove it's worse to convict an innocent man than let a guilty man go free, I can do it with simple algebra.

      Let's take the harm suffered by letting a guilty party go free. We can call it G. We will assume this is a positive value, since I think we can agree that letting guilty people go free is harmful to society.

      Now, let's take the harm of imprisoning an innocent man, which we will call I. Also positive, since putting an otherwise useful member of society in jail for no reason is something I think we'll agree is harmful.

      So let's look at the harm caused by each of our actions. Letting a guilty man free is of course G, as by our previous definition. Now to calculate the value of imprisoning an innocent man, we take our value I, and add G. Why? Well, in convicting the wrong man, we have inherently allowed the guilty party to go unpunished. So we can conclude that that G is less than I + G, i.e. it is better let a guilty man go free than to punish an innocent man.

      Didn't think of that, did you?

      So while convicting an innocent man might give you the opportunity to go tell that rape victim, "It's ok, we got him" it's a lie, and that lie not only destroys an innocent mans life, it lets the real rapist go free.

    17. Re:I wonder by Muad'Dave · · Score: 2, Informative

      Question: Did she submit the prints to the police, or did she get the only copy in case you were kidnapped? Around here, the prints _only_ go the the parents to hang onto in case the unthinkable happens.

      --
      Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
  4. Too Bad Fingerprinting is Useless by good+soldier+svejk · · Score: 2, Interesting

    At least as it is currently practiced.

    --
    It is cowardly, and a betrayal of whatever it means to be a Jew, to act as a white man

    -James Baldwin
    1. Re:Too Bad Fingerprinting is Useless by Kneo24 · · Score: 2, Insightful

      From what I gather there, it's not the methodology that's at fault, it's human error. Perhaps they need better training? In the end I wouldn't say that what we currently have is useless, but only that we should trust those examining the fingerprints a little less, perhaps.

    2. Re:Too Bad Fingerprinting is Useless by mikael · · Score: 2, Informative

      You could have come up with a better webpage than that. The Shirley Mckie case is a good place to start. The original event happened in January 14th, 1997. A decade later, a public enquiry is only just about to start in September 2008. There is a Wikipedia entry

      --
      Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads
  5. How Long Do They Have to be There by theshowmecanuck · · Score: 4, Insightful

    How long do the fingerprints have to be on the metal to corrode it enough to get a good fingerprint from this method? For example, if the perpetrator uses a cloth to wipe the fingerprints off the metal immediately after the crime, will the metal have corroded enough to still give a fingerprint by this method? Or do the fingerprints need to be there for some time in order to corrode the metal enough to give a good print? And if they wipe the fingerprints off is there still enough residue to still corrode the metal, or will they need to wipe the fingerprints off using some sort of solvent or cleaner? etc. etc. etc. It would be interesting to here more.

    --
    -- I ignore anonymous replies to my comments and postings.
  6. Passvation layers? by gboss · · Score: 2, Insightful

    What about metals with passivation layers, such as aluminum, titanium, and stainless steel? TFA does not address this at all... Sure, brass may be the main metal that they are going to need for shell casings, but a lot of guns are made with stainless steel.

  7. Seeing the wood for the trees by Hognoxious · · Score: 4, Insightful

    If the fingerprints are that persistent, then lots of other marks are going to be there too - probably including lots of other fingerprints. The hard part's not going to be detecting the prints, but separating the relevant ones out from the rest of the item's history.

    --
    Confucius say, "Find worm in apple - bad. Find half a worm - worse."
  8. Archaeology Applications by xdancergirlx · · Score: 5, Interesting

    Does this mean that we can see the fingerprints of people that handled old metal objects/chalices/swords/etc.? Maybe it would just be an item of curiousity to have a copy of Julius Ceasar's or Queen Elizabeth's fingerprints but I would put it on my wall! Maybe we could learn something about how fingerprints have changed (or not) over the course of history.

  9. Or salted lemon wet naps by spineboy · · Score: 3, Insightful

    I mean come on - not too hard to get around, but still it's interesting.

    --
    ..........FULL STOP.
  10. corrosion? how much? by Luke_22 · · Score: 3, Interesting

    Great method, ok, but i dubt it works for everyone.

    ok, we all have some corrosive sweat or alike in our skin, but that doesn't mean we all drop out the same amount of corrosive liquid.

    there are people who can not touch a motherboard 'cause it would end with a big mark on the metal, it could even lead to malfunction, this is well known in the industry... I guess they borrowed their idea from here...

    but how much of this corrosive is required for this method to work?
    also, saying "metal" is saying all and nothing... there are metals that corrode easily, others that don't...

    --
    "I was gratified to be able to answer promptly, and I did. I said I didn't know." -- Mark Twain
    1. Re:corrosion? how much? by TheRaven64 · · Score: 2, Interesting

      I don't know the details of this particular technique, but I recently came across an approach to getting fingerprints from fired bullet casings developed by some guys at Swansea which relied on Van der Waals forces - the amount of contact required is very small.

      --
      I am TheRaven on Soylent News
  11. Wrong game by spineboy · · Score: 4, Funny

    He's not playing Rock-Paper-Scissor, he's playing Bat-AcidSoakedSponge-Saw. The hand motions are a little strange though.

    --
    ..........FULL STOP.
  12. Corrosion is a complicated subject by Kupfernigk · · Score: 5, Interesting

    I have actually done research into chloride corrosion of brasses, and the answer is that it is enormously variable. Whether the brass is turned or stamped, the temperature, the number of steps in the stamping process, the sharpness of turning tools, the final treatment (grind to size, polish etc.) all affect the rate of attack. One would expect much the same for other metals, though considerable research would be needed. This will probably become a nice little earner for expert witnesses.

    --
    From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
  13. Re:NaCl by Arimus · · Score: 2, Insightful

    Err... expensive? buy a tub of marine salt (the kind you use to mix for marine fish tanks) and dump the weapon in that for a few weeks - ideally heated and then place in a bag and leave to corrode...

    --
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  14. Re:Problem solved for criminals: by srmalloy · · Score: 2, Interesting

    If you're going to police the area for your spent brass after you shoot someone, you're better off using a revolver, which won't toss empty cartridges all over the place. Beyond that, if you're doing it someplace where you don't already have your prints all over the place, thin gloves will keep you from leaving fingerprints in the first place... and you can dispose of the spent brass and gloves in widely-scattered places unrelated to the crime. If you're near the ocean, toss them in; the effect of the ions in the salt water will make any residual markings on the brass unrecoverable fairly quickly.

  15. Re:More forensic 'science' vaporware by lpangelrob · · Score: 2, Insightful

    As my lawyer friend says... the court of law doesn't necessarily judge based on who actually did the crime. It judges on who has the better story.

    That said, the story still has to be based on a fact.

    --
    -Rob

    Biblical fiscal responsibility