Question of the day- Fingerprints on fired cases?

[Miami_JBT]

I only worry about prints before committing a crime. Since the last time I committed a crime was never, not high on my list. I bet there are those here in law enforcement that might be able to add value.

I just make sure I commit my felonies in foreign countries.

 

[Miami_JBT]

 

[lysanderxiii]

Just because your fingerprints are on the case, doesn't mean you pulled the trigger.

It just makes you a person of interest, and chances are in most cases you already were "a person of interest."

 

[.455_Hunter]

Thanks to everyone who responded. My interest in the topic is purely scientific with how prints would survive the firing process.

 

[Howland937]

The oil on your skin, left on the case, will be burned/stamped something like that into the brass.

Forgot what the effect is called, I'm sure someone will know it.

Not sure either, but that's what happened to my finger prints on the muffler that fell off the lawnmower when I was a kid. By the time I realized it was hot, it burnt my fingerprints right onto it. Pretty sure it was actual skin and not just oil though.

They always catch people that go to WalMart.

Especially if it's either the Florida man or the Ohio man.

 

[tuckerdog1]

My wife once saw me loading mags with a socks on my hands. She asked why. Told her no fingerprints. She gave me a sideways glance and said "The stranger that sleeps beside me".

 

[Insignificant bill]

Yes, they will.
I load my carry gun with gloves on

Ha Ha

 

[Insignificant bill]

Don't leave casings at the scene of the crime

 

[WestKentucky]

It’s a shame @GunnyUSMC hasnt been here to weigh in.

 

[lemaymiami]

Yep, crime scene analysis is (and has been) an expanding science - What's not possible today may be possible tomorrow. For what it's worth - you'll know the moment you step on scene whether an auto pistol was involved (shell casings everywhere - and it only takes a moment to notice if more than one weapon was fired since you'll see different calibers, etc.), Scenes involving revolvers - no shell casings at all unless the shooter (good guy or bad guy) needed to reload... Multiple shell casings in the same caliber - may be clearly told apart if the primer strikes come from different weapons.. And so it goes...

My area, south Florida, was at the forefront of a number of advances regarding weapons used in crime scenes during my era (1973 to 1995). One of them was simply to bring to the scene a bundle of wooden dowels in different sizes -used to place into bullet holes in walls or other surfaces to exactly point to where the shooter was when weapon was fired. Another was the very first fingerprint - obtained from a dead body (and a conviction was obtained in that case) - a triple homicide in my city, actually.... I'd had some contact with the shooter once or twice months before and very glad I was nowhere near him when things went down (A very skilled martial artist, he used a pistol to conceal his involvement - then later drew a life sentence after conviction based on his fingerprint found on the leg of one of the three victims... ).

Anyone, good guy or bad guy, that makes statements after a shooting incident that are contradicted by the actual physical evidence on the scene... will have a problem (understatement...).

 

[Pat Riot]

Years ago at a CAS match it rained and we kept on shooting. When I was sorting and drying brass to clean after the match I found two cases with my dark finger prints on them. I figured I loaded the cartridge wet using dirty hand (cowboy action can get dusty and dirty in desert environs). The firing of the cartridge probably added pressure heat and soot and stamped my prints very nicely. The prints came off in the brass tumbler.
I haven’t seen that happen since.

 

[Bazoo]

I didn't know that fingerprints would survive being fired through the chamber. Though I had heard about it, and highly doubted it. Thanks all for sharing.

 

[Carl N. Brown]

Most criminals have mismatched ammo and never carry a full magazine.

In my limited experience, that's right.

 

[GunnyUSMC]

It’s a shame @GunnyUSMC hasnt been here to weigh in.

Finger prints are very hard to lift from cartridge cases. Most often what is found on cartridge cases is a etching for the oil left by the finger print. Basically the brass changes color where you touch it.
With normal fingerprints, a fine volcanic dust is used to dust an item. The oils from your finger tips absorb the dust. Then a lifter can be used to lift the print.
With a cartridge case, the etching does not absorb the dust so, no print can be lifted.
Ther was a guy that came up with a way to photograph the etched prints on cartridge cases, but the system was to expensive to justify even most labs to buy.
It is much easier to collect DNA from a fired cartridge case.

 

[GunnyUSMC]

In my limited experience, that's right.

Most criminals use extended magazines. Now when it comes to ammo, it all depends on the criminals.
Around here the small gangs would pay juveniles to steal ammo for sporting goods stores that have ammo out on the shelves.
The juveniles would go into the stores and steal a few rounds from different boxes of ammo and put them in their pockets.
I’ve worked cases where there were 15 to 30 rounds fired from the same gun, but there were four or five brands of ammo.

 

[lightman]

I've had the salt or the oil on my fingers etch my finger prints on a case before. Especially during the Summer months. When I first read the title this was my first thoughts.

 

[crstrode]

Next time you are at the range, pick up a bunch of random brass from the other shooters - use your gloves, of course.

Then, after your next gun-crime, sprinkle them liberally about the scene to keep the forensic techs busy . . just sayin'

 

[Jimfern]

I needed a chuckle on a Friday afternoon. Thanks guys!

 

[230RN]

I wipe my revolver cases and handle them with a cloth while loading... not for forensic reasons, but for corrosion reasons.

My untested feeling is that if corrosive elements on your fingerprints can create rust spots on the surface of a blued gun, it can transfer from the fingerprint-laden cases to the inside of the chambers as well.

It's not that bad here in Colorado where it's usually a mile or two between water molecules in the air (very low humidity), but I came from salty-humid New York City where even though you wiped your tools, they'd still get rusty.

So the "consciousness" of salt-laden fingerprints kind of stuck with me.

I don't wipe semi auto ammo except for the one I keep in the chamber... for the above irrational untested reasons. That is, as a matter of "good practice."

Terry, 230RN

 

[tmd16556]

I just use weak loads of Unique. The soot should hide everything.

800X is better, but discontinued.

Realistically, I figure it’s best to not shoot anything you aren’t willing to admit to shooting under oath.

I have had fingerprints burn or rust in on zinc plated shotshell hulls. I should probably be more careful with the DBI (Dove Bureau of Investigation) out to get me.

 

[roscoe]

Another reason to have a revolver or two. Wait - did i say that out loud?

 

[tws3b2]

If it were the same two cops doing the dusting for prints on the brass that did the dusting in my home after a breakin some years ago, I would say no. Everything was taken from one room. That's the one room where they did absolutely no dusting. Nor did they look for prints on the back door. Breaking the back door is how they got in. They did dust in one room. That's the one room in the house where nothing was disturbed. They did find ""ONE"" print in that room. ""One"". We lived in that house 14 years and used that room every day. Us, our kids, our grandkids and others. ""ONE"" print in that entire room??? We don't clean house that good. The cops asked us if we wanted them to dust for prints. The look on his face when we said "yes". It took us 3 days of scrubbing that carpet trying to get ""Some"" of the dust out. It's now over 10 years later and you can still see it.
Never heard from the cops again. Not one word.
Advice, A cheap pistol was taken that I got from my dad. A cheap little gun that was worth nothing so I never bothered to record the serial number. I only had it a couple weeks.
If you don't keep a record of the serial number and it's stolen, Even if it's found. You will not get it back.

 

[GunnyUSMC]

If it were the same two cops doing the dusting for prints on the brass that did the dusting in my home after a breakin some years ago, I would say no. Everything was taken from one room. That's the one room where they did absolutely no dusting. Nor did they look for prints on the back door. Breaking the back door is how they got in. They did dust in one room. That's the one room in the house where nothing was disturbed. They did find ""ONE"" print in that room. ""One"". We lived in that house 14 years and used that room every day. Us, our kids, our grandkids and others. ""ONE"" print in that entire room??? We don't clean house that good. The cops asked us if we wanted them to dust for prints. The look on his face when we said "yes". It took us 3 days of scrubbing that carpet trying to get ""Some"" of the dust out. It's now over 10 years later and you can still see it.
Never heard from the cops again. Not one word.
Advice, A cheap pistol was taken that I got from my dad. A cheap little gun that was worth nothing so I never bothered to record the serial number. I only had it a couple weeks.
If you don't keep a record of the serial number and it's stolen, Even if it's found. You will not get it back.

Most people knowledge on lifting fingerprints and matching them come from watching crime movies and shows.

Prints can be very hard to lift it the surface is not smooth and dust free.

And not everyone leaves good prints. If a person has very dry skin, they don’t leave good prints.

Most police officers don’t like lifting prints because, it’s messy. No matter how hard you try, the dust gets on your clothes and you.

During my career I lifted thousands of prints, but only had a handful that were matched.
Matching fingerprints is still used by most agencies, either in house or sent to labs, but the advancements in DNA identification has much higher results.

 

[GunnyUSMC]

Here’s a story that may help you understand how hard it can be to lift prints. I worked a burglary at a school where the suspect made entry through a window and stole a few items.

I was unable to lift anything worth turning in. This was at an elementary school. There was a class of students, about 20, that were watching me in one room. These kids were around 5 or 6 years old.

I asked their teacher if she would like to have her class make a fingerprint poster.

I had her roll out a long piece of white paper the had in the classroom. I had them write the students name on the paper. Below the name I had the student place their hands. I then used a magnetic dust to reveal their handprints. To make sure that I could make the prints show up, I had the students cup their hands and blow into them before placing them on the paper. We still had a little bit of trouble with a few.

We ended up with an 8 or 10 foot long piece of paper with all of their prints that the teacher hung on the wall.

 

[RetiredUSNChief]

Fingerprints are the result of the various chemical compounds left behind from skin oils. There are several different types of acids, salts, oils, and other compounds.

This means that not only can there be residue in the form of these oily compounds, but potentially actual etchings left behind on various types of metals depending on the particular alloys involved and how long those oils are in contact.

Here's a link which shows the compounds that can be found in human fingerprint oils.

https://www.researchgate.net/figure/Chemical-components-in-human-and-artificial-fingerprints_tbl1_336245457