We’ve seen it a million times in cop shows: there’s a crime in some relatively public place (a movie theater, restaurant, whatever) and the perpetrators flee. Then the crime scene people come in and collect evidence, especially fingerprints and DNA if appropriate to the scene.
Two minutes later some detective announces “We’ve got a hit on CODIS (?) or whatever it is” and the game is on.
Fine. But what about all the evidence they gathered that turned out NOT to be the people involved? The guy who brushed by a table earlier, the woman who dropped her used cup as she ran from the scene? Do their fingerprints and DNA records remain in various data bases forever? If so, how is it labeled? Unknown person #3928AJ921?
If so, do the police sometimes end up with really useless ‘hits’? “Yup, the perp is in our database! We can definitely prove he bought a box of Junior Mints on April 12, 2013 at the General Cinema theater in Youngstown!”
Which, of course, are fact-checked documentaries, and not entertainment wherein the details are skipped over, simplified or even falsified in the interest of moving the story forward, with suitable hooks before each commercial break.
Which doesn’t affect your question, overall, but using what’s seen on TV as a starting point without realizing it probably bears only a tenuous connection to reality is… not really up to GQ standards. I know we have some LE onboard who can maybe put the reality of how unknown info is processed and used before it ends up in some (mythologized) universal database.
Okay, so I actually do know TV shows aren’t documentaries.
The point is, if they collect all prints at the scene of a crime that happens in a basically public place, they will surely end up with lots more irrelevant fingerprints than ones connected to the crime. And, sure, they can no doubt eliminate some of them as belonging to other people they knew were there for normal reasons (employees, say, regular customers whose identities are known) what do they do with all the rest? Throw them out? Keep them on record with some label along the lines of “this person’s prints were found in a restaurant where a shooting happened”?
Or do they avoid it by not gathering ‘probably irrelevant’ prints to begin with? As in, they fingerprint a dropped weapon, or the victim’s body, or the particular teller’s window but DON’T fingerprint those tables where people fill out paperwork and such?
One reason I wonder is that once I heard on the news that a local liquor store had been robbed – and I’d been shopping there just a couple hours earlier. Quite likely I touched the counter at the cashier’s station, definitely I touched various bottles and shelves and some bottle openers I considered buying. Should I assume my fingerprints are on file, just waiting to snare me if I slip into my long-delayed life of crime? I mean, I’ve never been fingerprinted, like for a security clearance or something, but if I had? Would I have some 'splaining to do?
Until someone who knows for sure comes along, I’ll throw in the comment that depending on the crime and the scene that not every imaginable piece of evidence is collected, let alone processed-matched-and filed forever.
A couple months ago I watched a publicized US trial where a guy was charged with 30+ felonies. Little was in dispute during the trial and the guy obviously did pretty much everything he was accused of, but one thing the defense -while grasping at straws- brought up of interest to me (and relevant here) is that a couple things in the room connected to the crime that could have had his prints or DNA weren’t tested at all. It wasn’t needed for that case; they had plenty to prove what happened already. I’m assuming the crime techs know their job and have the training or direction to know what needs to be collected and what doesn’t.
So nobody’s going to be dusting all 15,000 bottles on the shelves for your typical liquor store robbery or taking DNA samples from the mop handles. If you know (roughly) who you’re interested in and where/what they touched you’re not going to spend thousands of dollars taking and preserving evidence of things irrelevant to the crime. I think only the most serious and high-profile of crimes would collect and preserve the kind of irrelevant evidence you’re talking about, and even then they’re not going to follow up on who’s print that was if it doesn’t match their person/s of interest.
There are several hundred thousand rape kits sitting untested in storage lockers and evidence rooms across the United States; if police departments don’t have the resources to test the primary piece of evidence in a high-order felony, the chances that they will have the resources to collect, prepare, and test lots of evidence in more routine crimes are basically nil.
For example, in your bank robbery scenario, the cops are not going to fingerprint the table where customers fill out the paperwork unless they’ve good reason to believe the bad guy touched that table bare-handed (e.g., an eyewitness or the security camera puts him over there), or its such an awful crime that they’re willing to grasp at straws (the bad guy murdered every teller, the security guard, every other customer, and the janitor, and then got away clean, or something of that magnitude).
So TV vs Reality. Fingerprints are a lot harder to find and collect in real life. In most of the crime scenes I’ve processed I have found none. Many surfaces are pretty much impossible to leave prints on.
Taking a print off of a surface that the entire public would touch is useless. Unless there in video of the suspect touching a specific point I wouldn’t even bother trying to get a print off of a public area.
If someone is in AFIS (CODIS is for DNA) it may take weeks or more for a hit to come back. If there is no hit I’m not sure how exactly AFIS designates it but I have received a hit years later when someone was arrested for another crime and finally printed.
Getting touch DNA is tricky and expensive. Our state lab won’t do touch DNA, the FBI will. Most DNA tests are for bodily fluids or some other sample left behind. No one is going to do a touch DNA test on your jewelry box after a burglary.
And while a fingerprint might prove that you touched a bottle, it does not have a date and time attached to it. I find it a little irritating when the ‘detectives’ in a TV show make huge leaps of deduction, based on highly suspect evidence. Doesn’t stop me watching them though.
In the UK, there is a statutory limit on the length of time fingerprints and DNA can be retained. If it leads to a conviction, it can usually be kept indefinitely, otherwise, it’s mostly limited to three years.
That surprises me. Not that a criminal might not leave prints – why wouldn’t he wear gloves? I certainly would if I decided to take up crime – but that many surfaces just don’t take prints.
But this actually answers my basic question: those unknown prints ARE stored away and could pop up in some totally different context long later.
Hmmm. Interesting. What if one of the fingerprints collected at a crime scene eventually comes back as that of a child kidnapped a decade before? Hmmmm.
Rape kits are not magic eight balls which reveal the truth. Something like half of rape kits remains untested since there is no identified suspect to check with, other major reasons they are not tested is since the charges are dropped, the guy confesses, or the results are not going to be probative in the circumstances, i.e the claim the accused makes is that the sex was consensual or the test was done outside a specific timeframe or the victim has acted in a manner that meant it was unlikely reliable evidence wqs going to be collected.
No they are not. Fingerprints and DNA are useful for identifying a person or linking him/her to some aspect of the crime. A table in a public place will have a plethora of fingerprints, which are smudged and overwrite each other; no one os going to test it.
Prints are definately useful if it’s at a home burglary scene and it comes back to a guy with no ties to the family and a history of burglaries. A print of someone in a public place not so much.
Fingerprints are oils on your fingers left behind when you touch something. Without a flat surface for the oils to adhere to there is no print left behind. On top of that the finger has to have been placed on the surface cleanly because if it’s dragged there will probably only be a smudge.
I dealt with a case not that long ago where a woman went to the hospital and had a rape kit done but didn’t want to report it to the police. She did a few weeks latter. If she decided to never report it then it would have been one of those untested kits. Stranger abduction rapes are extremely rare. A rape kit from such a case would go to the front of the line. In most cases the suspect is known and often does not disagree that sex occurred. In those cases there is no need for DNA and the testimony of the SANE nurse as to any injuries would be more important than DNA.
Isn’t a case in which there is no identified suspect precisely when you WANT to test the DNA, to see if you can match to some other case that maybe does have a suspect?
Yes that is true. That is the purpose of CODIS. I’m not confident to say it works like this in every state but here is how it works with us.
A sample is collected at the scene. It is analyzed for DNA. If a DNA profile can be found and there are no known suspects it gets submitted to CODIS. I don’t know what part of the process takes the longest but it may take months to get a hit back from CODIS if the suspect is in the database. Getting a hit from CODIS is not enough for an arrest warrant but it is enough for a search warrant requiring a DNA sample to be given. That fresh DNA sample taken either with consent or a search warrant is compared directly with the evidence.
Agreeing generally with what has been said above about DNA and particularly fingerprints. It is intensely annoying watching TV shows where the defence lawyer’s big point is that his client’s dabs are not on the gun, which “proves” it wasn’t him.
You get, IIRC, legible prints from about 20% of houses where there has been a burglary. And that includes prints from legit residents of the house.
Haven’t people been nailed with the help of fingerprints from the inside of discarded Obviously-Used-in-the-Crime latex gloves, or am I conflating a movie scene with the not-uncommon real-life occurrence of the mask used in the robbery being found in a nearby garbage can with hairs from the criminal in it?
If it has happened, it’s one of those examples in the textbooks of “there was this one time everything went perfectly right,” so Loach will probably be able to verify it if true.
It sounds possible but I don’t know of any real life examples. Latex would probably be a decent surface but the fingertips would not be perfectly still and the hands would probably be more sweaty than is ideal. Most likely you would just get smudges.
