Digitized Prints Can Point Wrong Finger At Innocent

February 6, 2005
By FLYNN McROBERTS and STEVE MILLS, Chicago Tribune

<snip> Across the country, police departments and crime labs are submitting fingerprints for comparisons and for entry into databases, using digital images that may be missing crucial details or may have been manipulated without the FBI knowing it. <snip>

An FBI-sponsored group of fingerprint examiners was concerned enough about the quality of digital images that in 2001 it recommended doubling their resolution. Three years later, though, the vast majority of police agencies still use equipment with the lower resolution.

Equally troublesome, the most commonly used image-enhancement software, Adobe Photoshop, leaves no record of some of the changes police technicians can perform as they clean up fingerprint images to make them easier to compare. <snip>

http://www.courant.com/technology/hc-fingerprints.artfeb06,0,6548220.story?coll=hc-headlines-technology

It's with the process in the first place. I wrote part of a piece of software that was bought by a company then later bought by the FBI. The problem is with the way the fingerprints are compared to account for different parts of the fingerprint scanned and to account for different skews. There's an adjustable margin of error that you use. If you set it too high, you'll end-up not finding legitimate matches or too loose, and you'll have false positives.

This is why you use the prints to compare to a known suspect rather than using the print to find a suspect.