Friday, November 3, 2023

Firearms Forensics

Crime Forensics have evolved into a science upon themselves. It's not just TV drama (although they often take free license with the truth).

I used to live where many of the crime scene protocols were developed. Thanks to two notorious serial killers: Ted Bundy and Gary Ridgeway.
While Ridgeway and Bundy did not use firearms (perhaps catching them might have been easier had they used guns?), the techniques used to process crime scenes helped evolve firearms forensics.

As technology progressed so did the science (or maybe it was the other way around?).
Today crime scene investigators have many tools at their disposal to figure out what type of bullet or firearm was used and hopefully the person responsible for pulling the trigger.

We have all seen it on TV, the CSI lab collects a bullet from a corpse or crime scene and compares it with a bullet fired from a suspects gun...and viola, we have a match


The riflings in a barrel are somewhat unique, although I am not sure that it has been proven that two guns CANNOT produce the same striations, the courts accept it as fact. 
Think about it for a moment, if you had two guns, both having the rifling cut by the same cutter on the same day under identical conditions, firing identical ammo, why would the striations be different?


I guess it is like fingerprints, it is unlikely that two guns could produce the same markings, but not statistically impossible.



Similarly you can examine the shell casings left behind at a crime scene.

The indentations left behind on the primers can also hep identify the gun they were fired from. 
For instance, most firing pins are round and in the case of Glock pistols, they are rectangular. This may help narrow down the search.
Firing pins can also leave behind unique impressions on the primers allowing investigators to match a gun to a fired  shell casing. As above, this is a pretty good indicator that a specific gun fired was used.

As a side note, fingerprints are often found on the brass cases as well.


Of course, the investigators would have to find a gun they THINK may have been used and then fire the same brand of cartridge from that gun and then compare it with the one found at the crime scene. The primer used in both would have to be the same. Some primers have a stronger material used to prevent slam fires.

 
Some anti-gun politicians are trying to force gun makers to engrave "micro-stamps" on the heads of the firing pins....This stamp would leave a mark on the soft material of the cartridge primer, leaving a tell tale clue for investigators.


The idea is that every gun would have their micro-stamp numbers on file, so when a casing is found at a crime scene the casing can be traced to the gun and then the owner. The problem is that you would need to register all guns (not gonna happen). In addition any new law would probably not affect older guns already in private hands.....What's more the criminals could also use revolvers or single shots which don't leave shell casings behind.

In addition the technology is not yet been perfected which leaves us with a lot of questions:
what if a gun's firing pin gets broken and needs a replacement? What if the owner files his firing pin down, will that become a crime? What if the micro-stamp wears off? What if the shooter uses a military spec primer made of a harder material (making the stamp too shallow to read)?

So let's say the gun was left behind, can the owner be easily traced? 

Despite what you see on TV, it's not that simple....most states in America do not have a compulsory registration of firearms. So tracking down the last owner may be impossible. 

The manufacturer's and wholesalers are required to keep accurate records of where all guns in their care were shipped to. From there the investigators can check with the dealer and find out who originally purchased the gun, but the trail could end there.

What if you have the gun but the serial numbers are missing?


The Gun Control Act of 1968 required that all licensed manufacturers & importers of firearms imprint their guns with a unique serial number.
Prior to 1968 many of the manufacturers did not put serial numbers on their shotguns and rimfire rifles.  

The act allowed the older, non-serialized guns to be "grandfathered".
It is not uncommon to find these older guns at gun shows and gun shops. I own a few myself.
The law also did not address the legality of making your own firearm.
What if, you stumble across a gun that you are sure was built after 1968 and cannot find the serial number? What if you have inadvertently purchased a firearm that has had the serial numbers obliterated?




It is pretty clear why a person would destroy the serial numbers on a firearm: the gun is most likely stolen.

Serial numbers were traditionally installed using tooling that press or stamp the numbers into the metal. The process will actually change the structure of the underlying metal.  So if there were a way to show the crystalline structure of the metal the serial numbers may reappear

Thanks to techniques pioneered by a Dr. Calvin Hooker Goddard we can restore previously obliterated serial numbers. He invented the idea of using an acid solution to expose the "crushed" metal. He came up with this idea during the investigation into the St. Valentines Day Massacre.

Both of the Thompson Sub-Machine Guns used in the attack (which were recovered from "Killer' Fred Burke's hideout) had their serial numbers ground or filed off. this picture shows one of the infamous guns.



This happens more than you think, my friend's uncle, a retired Game Warden, had a gun in his possession that was confiscated from a poacher. The rifle was a Remington Woodsmaster 30-06, the serial numbers had been ground off and without the help of a lab (usually not in the budget of the Fish & Game Department) there was no way to return it to the rightful owner.




Another kind of firearm forensics involves putting together information to prove the existence of a gun or that a gun was at a particular time or place.
Such is the mystery surrounding the death of the Nobel Prize winning author Ernest Hemingway. 
As many of you may know, Hemingway was an avid hunter and gun enthusiast.

His death was first reported as an accident...he was cleaning his gun they said..... 



Later it was disclosed that he had taken his own life. His wife (or another family member) had the gun cut into pieces by a local welding shop near their Idaho home and the pieces buried. Luckily the welding shop held onto one small piece.

This small piece allowed the authors of Hemingway's Guns to finally settle the debate about which gun Hemingway used to take his life.


Here is the piece saved by the owner of the welding shop in Idaho:


The authors were able to compare the piece to another W.C Scott & Son lock work.

 
The engraving was also a pretty close match.


The authors were able to prove that the shotgun that was destroyed by the welding shop was indeed a W.C. Scott & Son double barrel 12 gauge shotgun, one of Hemingway's favorite guns (pictured below).


In the case of Kurt Cobain's suicide, the police had plenty of evidence to suggest (or even prove) that is was indeed Kurt who took his own life. Still people think there may have been foul play involved. 

While shotguns do not have rifling and thus no way to easily trace a projectile back to a particular shotgun, there are always other clues. 

In Kurt's case, a box of 20 gauge shotgun shells along with a receipt from April 2nd was the link needed to prove the suicide theory. 
Testimony from the cab driver, who drove someone who looked like Kurt Cobain to the gun store on the day the shells were purchased, completed the link.