Sunday, May 19, 2013
Last month, a Portland woman reported that a stranger broke into her High Street apartment and tried to rape her.
Portland Police Department evidence technician Frank Pellerin examines a palm print on his computer monitor.
Photos by John Ewing/Staff Photographer
A close-up of a palm print is shown on Pellerin’s computer.
She didn't know him, and police had only a vague description to work with, but within a few hours officers identified the suspect, and tracked him to a West End apartment just two days after the attack.
Evidence technicians had retrieved a fingerprint from a foil condom wrapper, downloaded it into the regional crime lab's automated fingerprint identification system and matched it with Mohammed Mukhtar, an 18-year-old who had been arrested -- and fingerprinted -- for allegedly driving without a license a month earlier.
While the cutting-edge science of DNA analysis gets a lot of the glory in forensics, fingerprints -- and increasingly, palm prints -- remain a workhorse of crime scene investigation.
The palm is in many ways like a giant fingerprint, containing the same complex and unique combination of whorls and loops. Even when there are no usable fingerprints, evidence technicians can sometimes lift enough of a palm print to get a match.
Greater Portland's Metropolitan Regional Crime Laboratory has in the past two and a half years linked fingerprints taken from 295 crime scenes -- called latent prints -- to prints collected by corrections officers at the Cumberland County Jail, identifying suspects and closing cases.
In the 18 months since the jail began taking palm prints as part of its routine intake process, palm prints collected at crime scenes have been matched to offenders 65 times.
The automated fingerprint/palm print identification system consists of an extremely powerful desktop computer and a flatbed -- albeit state of the art -- scanner, which cost $45,000 and $30,000, respectively.
"I think that by far it's assisted us in solving more crimes than any other piece of equipment we've been able to purchase," said Assistant Chief Vern Malloch of the Portland Police Department, where the regional crime lab is housed.
The lab's success rate is so high that the manufacturer, SPEX Forensics, is using it to market its products.
The key to the lab's success has been its ability to electronically scan and compare prints quickly.
When a person is booked into the county jail, corrections officers scan prints electronically, and those digital images are automatically compared with all latent prints in the database.
"It's only a couple minutes, but you take a busy night with 15 or 16 people coming in and half of them intoxicated, it can be difficult. But the payback has been pretty good," said Cumberland County Sheriff Kevin Joyce, who oversees the jail and whose law enforcement division participates in the regional lab.
The jail has long served as a repository of information about offenders, including vital statistics, identifying marks and mug shots. It makes sense to collect electronic fingerprint information from all offenders the jail processes, even if their infractions are minor, Joyce said.
"If you spend extra time today fingerprinting somebody coming in for a driving offense ... they may be a burglary suspect on down the road," Joyce said.
The lab has archived 20,450 sets of fingerprints -- although some are multiple sets from the same offender because they're taken each time a person is booked at the jail. It has archived 10,500 palm prints.
Of these, 1,227 fingerprints and 135 palm prints collected from crime scenes are from unknown persons.
When prints are collected from a crime scene, they are scanned into the system and immediately compared to all known offenders and existing crime scene prints in the system.
The "hit rate" for the number of latent prints that match with a known offender's prints exceeds 20 percent.
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click image to enlarge
A booking officer scans a palm in the intake area at the Cumberland County Jail in Portland last week.
Tim Greenway/Staff Photographer