Fingerprints Can Now Be Dated To Within a Day of When They Were Made (economist.com) 25
Writing in Analytical Chemistry, Paige Hinners and Young Jin Lee of Iowa State University say they have figured out an accurate way to data to within 24 hours when a fingerprint under a week old was made -- and thus whether it is associated with a crime temporally, as well as spatially. The Economist reports: They knew from work conducted by other laboratories that the triglyceride oils contained in fingerprints change by oxidation over the course of time. That provides an obvious way to date prints. The problem is that the techniques which have been applied to analyze these oils are able to distinguish age only crudely. In practice, they can determine whether or not a print is over a week old, but nothing else. Dr Hinners and Dr Lee wondered if higher precision could be obtained by thinking a bit more about oxidation. Oxygen molecules in the air come in two varieties. Most have a pair of atoms but some, known as ozone, have three. Though far rarer than diatomic oxygen, ozone is more reactive and also reacts in ways different from those of its two-atomed cousin. The two researchers therefore decided to focus their attentions on ozonolysis, as triatomic oxidation is known.
Triglycerides, as their name suggests, are three-tailed molecules. Each tail is a chain of carbon atoms, with hydrogen atoms bonded to the carbons. The chains are held together by bonds between the carbon atoms. These are of two varieties, known as single and double bonds. Single bonds are, in chemistry-speak, saturated, and double bonds unsaturated. By extension, molecules with one or more double bonds in them are also referred to as unsaturated, while those with only single bonds are called saturated. Unsaturated bonds are more reactive, and it is here that ozonolysis does its work. Ozone breaks up triglycerides at their double bonds, with one or more of the ozone's oxygen atoms becoming attached to the carbon chain, to create new chemical species. In principle, this should result in a gradual loss of unsaturated triglycerides and a concomitant rise in the reaction products of ozonolysis. And that, in practice, is what Dr Hinners and Dr Lee found.
Triglycerides, as their name suggests, are three-tailed molecules. Each tail is a chain of carbon atoms, with hydrogen atoms bonded to the carbons. The chains are held together by bonds between the carbon atoms. These are of two varieties, known as single and double bonds. Single bonds are, in chemistry-speak, saturated, and double bonds unsaturated. By extension, molecules with one or more double bonds in them are also referred to as unsaturated, while those with only single bonds are called saturated. Unsaturated bonds are more reactive, and it is here that ozonolysis does its work. Ozone breaks up triglycerides at their double bonds, with one or more of the ozone's oxygen atoms becoming attached to the carbon chain, to create new chemical species. In principle, this should result in a gradual loss of unsaturated triglycerides and a concomitant rise in the reaction products of ozonolysis. And that, in practice, is what Dr Hinners and Dr Lee found.
Whatever... (Score:3)
Finger prints have never been an exact science and while this is potentially handy we already know that it will be difficult to be used as exculpatory because the moment the prosecutor finds out dating does not match the time of the crime Prosecution is going to either ignore, claim it does not exist, bury it, or say that it is too inconclusive to rule as exculpatory. And most importantly, this all still hinges on the quality of the training and skill of the technicians performing the forensic science against the pieces of evidence at hand which can range from straight up fuckery...
https://www.nbcnews.com/news/u... [nbcnews.com]
to pure unfortunate accidents in the lab...
https://www.thestar.com/news/w... [thestar.com]
Shit happens and often times for the sake of expedience we let a whole lotta shit slide and I do mean a whole lotta!
for some humor!
http://hyperboleandahalf.blogs... [blogspot.com]
Re: (Score:2)
Kind of like the time I used a ultrasound humidifier with hard water and wondered why my gas stove wasn’t combusting properly as the normally blue flame was almost completely yellow/orange. Took me a minute or two to put the two together.
Re: (Score:2)
"Sounds to me like a single ozone air purifier will mess with the results. "
Imagine what an Ozone generator would do.
I have one to destroy wet dog smell in my car and I disinfect one room at a time if someone was sick, it would even kill a cat if it was inside.
Re: (Score:2)
Or temperature. Or the pH of the surface with the fingerprint. It would be interesting to re-run these with fingerprints lifted with clear tape, such as some police use to take fingerprints from awkward surfaces. Also, how does the talcum or graphite used to dust for fingerprints affect the measurements? This would need a great deal of additional testing, preferably done rigorously by competent chemists with competent forensic scientists, to get reliable results.
Re: (Score:1)
You're right.
Fingerprints suck.
Smithsonian 2019: https://www.smithsonianmag.com... [smithsonianmag.com]
American Council of Science and Health 2017: https://www.acsh.org/news/2017... [acsh.org]
Australia 2017: http://theconversation.com/fin... [theconversation.com]
And they all point out the bias in reporting. If the prints don't match you won't hear about it from prosecutors. If they do match it's a coincidence. How much of a coincidence... well that's why we have a "trial".
E
Re: (Score:2)
Unfortunately, like all science that makes its way to the courtroom, prosecutors will likely abuse it.
The moral of the story (Score:2)
Leave your cell phone at home, and wear gloves. Maybe gloves with a latex glove over them.
Re: (Score:2)
"Leave your cell phone at home, and wear gloves. Maybe gloves with a latex glove over them."
First, you'd wear the gloves _under_ them and the other gloves they'd better be brand new, with the DNA of the people on it who tried them out in the shop.
Re: (Score:2)
I have a feeling we're going to see you on the news one day.
Nice theory (Score:1)
In principle, this should result in a gradual loss of unsaturated triglycerides and a concomitant rise in the reaction products of ozonolysis. And that, in practice, is what Dr Hinners and Dr Lee found.
In practice, though, have a lightning storm blow through the area and the concentration of ozone increases dramatically, causing the triglycerides to deteriote far more quickly, leading to "increased aging." This aging method is unreliable and will be challenged in court and dismissed fairly quickly as a source of evidence, I'd suggest.
Re: (Score:2)
1. Industrial polution
2. Somebody cleaning with a good old classic bleach nearby.
3. ....
While there is SOME value in the idea, I do not see how you can have a proper calibration curve.
Re: (Score:2)
You mean like eye witness statements? (Score:2)
Which should also be dismissed for not being reliable.
Remember that this is a legal system where we're still using "lie detctors"! We're one step away from still doing voodoo rituals!
Law enforcement today, is nothing more than a ritual for finding the closest scapegoat to commit an act of revenge violence on. That's it.
Nothing scientific about it. Nothing fair about it. Let alonr improving the world. It's just about revenge porn. Highlight on "porn".
Re: (Score:2)
if you mean polygraph, they are not admissible in court. At least in the US...
Re: (Score:2)
This aging method is unreliable and will be challenged in court and dismissed fairly quickly as a source of evidence, I'd suggest.
Don't confuse what should happen with what will happen.
So if you need an alibi (Score:2)
All you need to do is age your fingerprints with an ozone generator.
Re: (Score:2)
Re: (Score:2)
That's brilliant! You know where they are and have time to destroy them but why do that when you can leave them behind and use this brilliant solution instead!
Reverse psychology: "So Mr. DA, you're saying that I knew where my fingerprints were, and that I had plenty of time to wipe them off, but instead I opted to tediously ozonate them, and leave them behind so you could find them and prosecute me? Good luck selling that to the jury!"
Re:So if you need an alibi (Score:4, Insightful)
Re: (Score:2)
You don't seem to be able to grasp that it is far better to not be a suspect at all than to go to trial and "win". I put that in quotes because a defendant never wins by going to trial. The best one can hope for is to not lose so badly that you get convicted. You seem like a teenager who has read too many campy crime novells.
Greying senior with a sarcastic sense of humor, actually.
Re: (Score:3)
All you need to do is age your fingerprints with an ozone generator.
A 24 hour window is practically useless as an alibi, you could have been almost anywhere and returned to make those prints in that time span. That you left fingerprints here four days ago doesn't exclude the possibility that you returned with gloves two days ago so all aged fingerprints can do is implicate you not exclude you.
I suspect this will mostly be used to catch people who are fully aware their prints will be found but not how accurately it can be timestamped in lying. "So you've not seen the victim
Re: (Score:2)
It could also be useful where the prints are supposed to be older, such as when a couple splits up and one keeps the home. Fresh fingerprints would be evidence of visiting the premises afte the split.
IFF you know the *local* ozone concentrations (Score:2)
of the last seven days, that is.
And by local, I mean, around the fingerprint!
Which will be completely different in a house surrounded by forest and in a city building.
But be sure that that will be ignored and people will be convicted based on false conclusions anyway, because law enforcement is only about finding the closest scapegoat to commit revenge on to feel good, and nothing else.
Sure (Score:2)
DNA can point to a rape suspects within a day, but copy sometimes need 5 years to do it.
Or not.