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For fingerprint analyst, the devil is in the details
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No two people have been found to have the same fingerprints. Recently, fingerprint analysis was at the forefront of solving the Edricus Mayfield attempted rape case. - photo by Scott Rogers

Herman Cronic’s loupe takes his vision down to a microscopic world of whorls, loops, arches and minutiae that are vital for his Gainesville Police Department colleagues.

But in the local database, there are roughly 64,000 fingerprints and 40,000 palmprints, with the latter needing a large amount of data storage, Cronic said.

“That’s one of the problems that the FBI has encountered has been the storage of palmprints, and I think they’re in the process now of trying different systems to accommodate that, to search palm impressions. They contain a lot of data … and it will eat up storage space,” Cronic said.

Cronic, who has been working in this field on and off since 1999, was called last month to testify in a burglary and attempted rape case, in which the defendant, Edricus Mayfield, 19, was convicted.

Mayfield was one of the major cases for the Gainesville Police Department that relied on palmprint evidence to reach a conviction.

Following the conviction, jurors said one of the deciding factors was a print found between a screen and the window of the crime scene.

In 2010, the department bought an AFIX computer system through a $25,000 Department of Justice grant, which compares prints from a crime scene to booking records.

Cronic said he needs at least 12 matches of fingerprint minutiae, or points, before he makes an ID. The minutiae include where a ridge might bifurcate, end or cross over.

“When you’re booked in, it will mark those points and draw the correlation between the two. That’s what a computer does. Now when I get a response back, I have to go in and look at it and verify — I have to keep the computer honest — to make sure everything it has marked correlates with what I have marked,” Cronic said.

Cronic will check to see if there is a consistent pattern and quality within the print.

In the recent trial, the defense attorney referenced the March 2004 Madrid train bombings.

Two months after the death of 200 people, an Oregon man was wrongfully arrested by the FBI based on a print found on a bag of detonators, according to a report by the Office of the Inspector General. He was released from custody after the Spanish National Police identified the actual suspect.
“The (Office of the Inspector General) found that a significant cause of the misidentification was that the (latent print units) examiners' interpretation of some features in (the fingerprint) was adjusted or influenced by reasoning ‘backward’ from features that were visible in the known prints of (the wrongfully accused). This bias is sometimes referred to as ‘circular reasoning,’ and is an important pitfall to be avoided. Having found as many as 10 points of unusual similarity, the FBI examiners began to ‘find’ additional features in (the fingerprint) that were not really there, but rather were suggested to the examiners by features in the (the wrongfully accused’s) prints,” according to the report.

From his reading of the case, Cronic said he felt there were not enough points to make an ID, and there were also issues with the quality of the print.

In the Mayfield case, Cronic said a print found on the window had more than 60 matching points.

“On a window, typically they will evaporate more quickly, especially if they are exposed to direct heat. … It’s 99% water. It’s going to evaporate sometime,” Cronic said.

Mayfield’s attorney Craig Pake filed a motion for new trial May 17 arguing that the verdict was “contrary to the evidence and without sufficient evidence to support it” while also “strongly and decidedly against the weight of the evidence.”


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