a finger print question

[dsc]

With the case of the lawyer out of Oregon whose fingerprints were mistakenly claimed to be in Spain, I am left wondering just how accurate fingerprints accually are.

I admit until fairly recently I had assumed that the way fingerprints were identified was by laying a trace of the print you have over a trace of the print you think it is and comparing. But, instead it is by picking a certain number of match points. Even if the first method were used with only a partial print it still would be much more accurate than the second.

So my question is, just how infalliable is this method of identifying prints?

[Killarney]

1. I think the deal with that guy

was that there are 8 points of a fingerprint. He had 6 out of 8 match, so the dillholes in the FBI went with it. It was not a complete match at all.

And he spent 2 weeks in prison!

Very scary. It could have happened to anyone, but I have an inkling it happened to that poor guy because he was Muslim.

[jpgray]

4. I thought twelve is the standard here? Did they lower it? (nt)

[Killarney]

6. You could be right.

I'm just going from memory on a story I read about the lawyer that the FBI matched 6 out of 8 and went for it. I could be remembering the number wrong.

[jpgray]

7. Okay here we go--blurry photo, not a positive ID

Here's the subjective part sangh0 was talking about--this guy that did the ID apaprently had a history of botched fingerprinting:

The officials told The Oregonian that the original evidence -- the print lifted from a bag found in Madrid -- was destroyed in processing by Spanish authorities. FBI officials did not learn this crucial fact until after prosecutors had arrested Mayfield and assured a federal judge they were confident his print matched the Spanish evidence.

Last week, law enforcement officials acknowledged that the misidentification of Mayfield was based on a digital photo of the print, an image officials now say was not sufficiently clear to provide positive identification.

http://www.oregonlive.com/news/oregonian/index.ssf?/base/front_page/10858322779300.xml

[sangh0]

2. It's very subjective

Not only are there no rules or standards as to how many match points make a match, there are no rules or standards setting out what a match point is.

IOW, it is entirely subjective.

[jpgray]

3. It's a weird system. You have to have at least twelve 'points'

for 'points of comparison', to successfully use the fingerprint as evidence to identify an indvidual in America. It's actually pretty accurate, and a false ID is rare. Here's an article on fingerprinting and its origins:

http://faculty.ncwc.edu/toconnor/315/315lect05.htm

[dsc]

5. I have to admit

that I would have thought it was actually impossible until a few years ago (when the FBI lab scandal broke).

[skypilot]

8. I have a fingerprint question, also.

It's a very different type of question from dsc's though.

From what I remember, there are 3 fingerprint patterns (right?):hooks, swirls, and loops. Is it normal to have different patterns on different fingers?

[zbdent]

9. I've never been classified as "normal", but my index fingers

have different fingerpring pattern styles, and neither match the rest of my fingerprint styles.

[skypilot]

10. Damn, I'm not special.

:) I have different patterns on my thumbs. I didn't notice it until a few years ago.

[Monte Carlo]

11. From what I understand, it's not the fingerprints, its the human element.

I remember watching 60 Minutes, and I heard that every law enforcement agency around the world basically has their own standards and systems for identifying matching fingerprints. Some use more points than others, some use less, and sloppiness and sleaziness are rampant. Very little is stopping some FBI agent from purposely identifying the wrong person. It's almost chaotic.