Written in Blood by Mike Silverman & Tony Thompson

Author:Mike Silverman & Tony Thompson [Silverman, Mike]
Language: eng
Format: epub
ISBN: 9781448167425
Publisher: Transworld
Published: 2014-02-13T00:00:00+00:00

13

SOONER OR LATER, every TV detective drama shows a fingerprint being fed into a computer which, a few moments later, flashes up the word ‘match’ on its display screen, often accompanied by a picture of the suspect. Despite the huge processing power of modern computers, however – they are able to search through up to 500,000 prints in a single second – fingerprint computers never actually provide investigators with a single suspect. Instead, the system produces a list of potential matches in order of closeness, and these are then examined manually by a human operator or fingerprint expert. Before they are considered final, these matches are verified by other qualified fingerprint experts.

Although everyone’s fingerprints are, theoretically, unique, there are prints which can be very similar and this can occasionally cause difficulties.

Following a series of terrorist bomb attacks on commuter trains in Madrid, Spain, in March 2004, which left nearly 200 people dead and injured more than 2,000, Spanish police investigators recovered several poor-quality, partial fingerprints from detonator caps found at the scene of one of the blasts.

These prints were submitted to the FBI for analysis and fed into AFIS – the automated fingerprint identification system. The system generated a list of around 20 possible prints, one of which was then triple-checked by hand and subsequently declared to be a 100 per cent match to Brandon Mayfield, a lawyer from Oregon.

Mayfield seemed to tick many of the boxes in the FBI terrorist profile. A former officer in the US Army, he had married an Egyptian national and converted to Islam. A year earlier he had been working pro bono on the case of one of seven men accused of travelling to Afghanistan to fight on the side of the Taliban.

Mayfield was arrested and held for two weeks while further investigations were carried out. When the Spanish police did their own work of comparing Mayfield’s print with the one recovered from the scene, however, they found that, while there were eight points of similarity between them (only half of the 16 ‘required’ – there was no official standard – for a match in the UK), they were far from a 100 per cent match.

The problems were that the initial print was of poor quality, that it provided only a partial view of the entire finger and, perhaps most crucially, that the FBI experts doing the manual check had been told in advance that Mayfield seemed to be a strong suspect, which had possibly affected what should have been an impartial fingerprint examination. Mayfield was released without charge. He later received an apology from the US government and a settlement of $2 million.

It was a similar story when 51-year-old Marion Ross was found murdered in her Kilmarnock home in January 1997. Her ribs had been crushed and she had been stabbed in the eye and throat.

She was known to be security-conscious and there were no signs of forced entry at her home, so detectives from Strathclyde Police were convinced she either knew her killer or had willingly let the person responsible into her home.

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