Fingerprint Science?

Interesting piece published in the LA Times yesterday questions the reliability of fingerprint evidence, especially the types that we often see in defense cases: smudges or partial prints. For full article, click here.

When Thomas and Ann Farrow were found murdered in their paint shop, their heads crushed with a blunt object, the only clue was a bloody right thumbprint on the store's empty cash box.
The brazen murder shocked the people of Debtford, a sooty industrial suburb of London. They clamored for police to find the killer.

The year was 1905. Forensic science was in its infancy. Scotland Yard had only recently begun collecting carefully pressed fingerprints from criminals, stashing the cards in pigeonholes of a makeshift filing system.
But Scotland Yard Inspector Charles Collins believed that the bloody print could help him solve his crime. After learning that a man named Alfred Stratton had been seen near the crime scene, he collected the unemployed ruffian's thumbprint and compared it with the one left at the crime scene. A close inspection showed there were 11 minute features that the two prints shared.

The prosecutor at Stratton's trial told jurors the similarities left "not the shadow of a doubt" that the crime-scene print belonged to Stratton.
But the defense had a surprising ally at their table: Henry Faulds, a Scottish doctor who two decades earlier was the first to propose using fingerprints to solve crimes.
Faulds believed that even if fingerprints were unique -- there was, after all, no scientific basis for the popular assumption -- the same was not necessarily true of "smudges," the blurry partial prints accidentally left behind at crime scenes in blood, sweat or grease.
A single bloody thumbprint, he felt, was not enough evidence to convict anyone of murder.

Stratton's trial would be the first test of the new science of fingerprinting, and it raised concerns that, more than a century later, still have not been addressed.
Today, fingerprints are once again on trial.
In 2007, a Maryland judge threw out fingerprint evidence in a death penalty case, calling it "a subjective, untested, unverifiable identification procedure that purports to be infallible."

The ruling sided with the scientists, law professors and defense lawyers who for a decade had been noting the dearth of research into the reliability of fingerprinting. Their lonely crusade for sound science in the courtroom has often been ignored by the courts, but last month it was endorsed by the prestigious National Academy of Sciences.

The question is not whether fingerprints are unique -- most scientists agree they probably are, though that assumption remains largely unstudied. The issue is whether the blurry partial prints often found at crime scenes -- what Faulds called "smudges" -- are sufficient to identify someone with any reliability.

The answer: No one knows. There are no national standards for declaring a fingerprint "match." As a result, fingerprint identifications are largely subjective.