Fingerprints Recoverable From Cleaned Metal 178
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."
Re:Too Bad Fingerprinting is Useless (Score:3, Informative)
You could have come up with a better webpage than that. The Shirley Mckie [slashdot.org] 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 [wikipedia.org]
Re:I wonder (Score:5, Informative)
This question was raised and discussed by Alexander Volokh in n Guilty Men [ucla.edu].
Re:I wonder (Score:5, Informative)
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.
Re:I wonder (Score:1, Informative)
Re:I wonder (Score:3, Informative)