As the title says – I’m wondering how we can really use fingerprints accurately, when there could be so many variables which could alter your fingerprint, especially so that a partial print might be altered. Is it just based entirely on the ridges/patterns? Do they really not change much at all, even if you lose/put on weight, are really cold/too warm, damage your skin eg scratch or burn your fingertips, have been in the shower so your fingertips go all raisin-y, or you’re applying less pressure one time and more the next?
Sometimes when I’ve been in the bath or have been cleaning or whatever I struggle to unlock my phone with my Touch ID haha, so I wonder how reliable fingerprints actually are.
In: Biology
Now days they roll your finger so they get a wide print, they also do your palms, side palms and whole hand with finger printing machines. Years ago they would have to determine by eye sight so there were multiple false convictions. Some criminals use to try and burn their finger prints with acid, heat..oh and some departments take a picture of your eyes now. You have to stare into this little machine and it takes a pic of your eyes up close which can also be used to identify you
They don’t change much with transient variables like heat/pressure, it’s based entirely on the ridges/patterns and the pattern is structural to your skin. If you damage the structure permanently (injury/burn) then that will change your fingerprints but, unless you erase them completely, the parts that remain are still the same as they were before so something like having a cut doesn’t really change your fingerprint, it just draws a line through the middle.
Think of your fingerprint like a line drawing on a piece of paper. You can wad the paper into a ball and unfold it again, draw over it with a pencil, tear the sheet, get it wet and dry it out again, but the drawing is still basically the same and identifiable to somebody unless you *really* wreck the paper in a way that you can’t reassemble it.
The issue with TouchID on your phone is the phone having trouble *reading* your fingerprint, not that your print changed. In particular, they really don’t work well with water on them. Forensic investigators aren’t lifting prints using that technology. *If* you get a fingerprint from a crime scene then you can try to match it, and if it does match that becomes pretty compelling evidence, especially if it’s full prints or multiple fingers. Partials aren’t as compelling, for exactly the reasons you’d think.
If you really want to fool the cops you need to not leave prints…either wear gloves or destroy your finger structure to the point that you don’t leave identifiable prints. There are cases of criminals trying to do just that with burns or acid.
Actually, they are.
I’ve heard tales of people employed in heavy hands-on work not being able to provide a fingerprint.
Some variables actually do affect your fingerprints. I accidentally burnt the skin on my right hand thumb, and my college biometric couldn’t recognize my fingerprints, so I had to write a letter as an alternative.
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