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» Hatrack River Writers Workshop » Forums » Open Discussions About Writing » Fingerprints and DBs

   
Author Topic: Fingerprints and DBs
micmcd
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I have a practical question about fingerprint lookups, and since dedicated googling has given me widely divergent answers, I'll post the question here.

How long does it take to search through a database of fingerprints, assuming the "query" fingerprint is of high quality?

I've seen estimates of a week to a month, depending on how high-priority the search was (prints at a murder scene are pulled faster). But this priority-based divergence leads me to believe that it's not the search that takes all that time.

Suppose you have a perfect quality print, because you have the perp at your station and you can take as many copies as you like. And your priority, right this very second, is to run that person's prints against the database of prints from unsolved crimes in your city. Let's assume you live in a big city.

Is this a computationally intensive task, something you would feed the input and then let the computer work for weeks on? Or would you click "match prints," wait a few minutes, and then have your answer?

The situation in my WIP is something like this perfect case scenario. An extremely wealthy board of directors of a private high school decide to have all the teachers fingerprinted by the police (paid privately for overtime) and scanned against unsolved crimes in Philadelphia. Ordinarily, this wouldn't be high-pri, but the board of directors has given the Philly PD buckets of money to just go ahead and run the prints in one day, effectively paying people who were on vacation to just go ahead and do it. My protagonist is one of the teachers, and he's pretty sure his prints have been found at major unsolved crimes (a series of murders). Should he be expecting the cops at his door tonight? Next week? Next month?

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LDWriter2
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I would think it would depend. On do you or your PD characters that is, have a search software that can do the searching or does he-she-it have to eyeball each fingerprint? If software it would also depend on how good it is and how fast the computers are. The software could bring up a hundred selections that have to be eyeballed or be good enough to lower that to ten.

And how fast you want-need it to be. The PD could get lucky or things go wrong and it takes them five times as long as normal.

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redux
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I gave my google-fu a try and came up with this:

http://forensics4fiction.com/2011/09/01/afis-the-automated-fingerprint-identification-system/

Apparently, for a good quality print, it can take 20 minutes.

I believe the one week/one month estimates have more to do with administrative concerns.

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micmcd
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Nice find, redux. Best info I had previously came from here: http://onin.com/fp/lpfaq.html#how_long_do_fingerprints_last, which was quite informative, but didn't give me the answer I was looking for.
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Robert Nowall
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It was known that everyone's fingerprints were different from sometime in the 1700s...but it took over a century to come up with a practical way to index them, because they're not "A to Z." Working through them is still reportedly tedious and difficult, and all the more so if they're not IDed, but lifted from something at a crime scene. I think you might have some time less than a week, maybe a day or more if the same prints are at multiple crime scenes.

I don't know what they use to go through them today...but there's an excellent account of how the FBI worked their fingerprint files in the book Hellhound on His Trail, a recent account of the assassination of Martin Luther King and the capture of James Earl Ray. (Recommended highly.)

As I recall (I don't have it in front of me), the FBI started working through millions of prints, but without something more to look for, some way to narrow it down, it would take months if not years. (This was in 1968, and the Bureau reportedly to this day is computer-phobic, so I don't know how they handle it now.)

Somebody had the bright realization that, since the man they were looking for had been acting like a fugitive from justice, maybe he was, and maybe his prints were already in that particular file. Sure enough, it only took a few hours to come up with a positive ID on them...

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EVOC
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When fingerprinting via Livescan, it can come back very fast. Anywhere from hours to three days. To give you an example. My security company used to finger print perspective employees. I got results typically in three days. Some can take a few weeks. I was certainly not a high priority.

California DOJ's Website says:
quote:
Most of the time, results are released to the applicant agency within three business days. Delays can occur however, and can be caused by a number of things including: poor fingerprint quality, the existence of criminal information in the applicant’s record, the existence of a manual fingerprint card (whether criminal or applicant) in the applicant’s file, birthdates before 1920, and incorrect data on the submission. An agency should NOT assume the applicant has criminal information on their record simply on the basis of a delay notification.
Thirty days is considered extreme even with a criminal record. Mos of my results were within 24 to 72 hours. I had one take a week and he had a criminal record in three other states.

Since most of mine were reasonably low priority. I would say your character could realistically expect a knock on his door that night, or the next day (if they didn't know as soon as they printed him).

Now that is if it was done by Livescan (computer based). If you are talking ink and paper... you could expect it take months. (Took me three months o get some back).

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micmcd
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Oh, so if they collected the prints by ink, that wouldn't go into the computer right away? Do police have digital scanners?

The only time I've ever had my fingerprints taken was with ink b/c I was applying for a job that required it. That was ten years ago, come to think of it.

I have new technology to look up.

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LDWriter2
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My bank has a scanner for fingerprints, a little box about an inch square, with a lens on top.

As to if the police have digital scanners, that depends on the force. Some seem to be always behind while others are very close to being up to date with the latest.

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EVOC
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Almost every police department has a Live Scan machine for booking now. Ink prints are not common anymore. Live Scan Machines are pretty big, but there are mobile versions (some that even connect to a laptop). This wouldn't be something they would carry around with them on their belts (though I imagine that technology is coming).
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