March 10, 2010

Technology taking grunt work out of criminal investigations

DAVID HENCH

— By

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20090828_Forensics
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20090828_Forensics

Staff Writer

William Farrell was a rookie officer in 1956 when he became one of the Portland Police Department's first evidence technicians.

''There were three of us guys,'' Farrell recalls. ''They gave us a fingerprint kit, a four-by-five camera and flashbulb equipment and told us we were evidence technicians.''

They learned how to dust for fingerprints and lift the images with clear tape, but they continue to patrol a beat.

Today, police investigators in the Portland area can show up at a crime scene with a hand-held light source that can illuminate faint blood smears and otherwise invisible fingerprints.

They can use a computer to identify key features in a fingerprint and instantly compare it to a digital catalog of known offenders. And they can use computers to recover clues like deleted e-mails and cell phone records.

Last week, nine communities in Greater Portland unveiled a $1.5 million crime laboratory at the Portland police station, a regional effort to take advantage of the best that science can offer at a price that small towns can afford.

The Metropolitan Regional Crime Laboratory will make sophisticated techniques and the training they require available to suburban police departments that otherwise would lack access. The lab also will ease some of the workload of the Maine State Police crime lab in Augusta and improve the quality of samples sent there for DNA analysis.

Much of the regional lab's benefit involves aspects of evidence processing that never makes the television crime dramas, said Sgt. Robert Martin, head of Portland's evidence technicians. For example:

n Bloody clothing must be dried in a ventilation-controlled environment to prevent contamination.

n Separate rooms for processing evidence from victims and suspects reduces the chance of cross-contamination.

n Dangerous chemicals for enhancing fingerprints are applied with an apparatus that prevents officers from breathing the fumes or fine powder.

n Individual examination rooms and secure lockers mean officers can start work on evidence and then, if called away, lock it up until they can return.

The lab has a $30,000 fingerprint analysis computer, which automatically identifies key features on a fingerprint image and matches them against a database of samples.

The system was delivered in June and already has found 21 matches between crime-scene fingerprints and those in a database of known offenders.

''This is going to be the workhorse of the unit,'' Martin said.

Just a few months ago, it would have taken countless hours to compare a suspect's fingerprint with each print on the card from known offenders.

''Property crimes (like burglary) are probably still the biggest number of crimes we are seeing,'' said Martin. ''If you've got a good print, there's no need to do DNA on it.''

DNA analysis is time-consuming and expensive, and the state has a significant backlog of samples.

A $25,000 alternate light source will be used on bed linens and clothing, making blood and semen visible with special goggles.

Digital photography and enhancement will help officers ''see'' evidence in ways they otherwise could not.

An $8,000 portable alternate light source will let agencies use the light to find trace evidence at crime scenes, not just in the lab.

Although forensic science can't replace traditional detective work, its role in putting criminals behind bars is more important than ever.

''The age of computers has allowed us to conduct searches of massive amounts of information,'' said Attorney General Janet Mills, as she toured the new facility in Portland last week.

She noted work done at the state lab in the recent cold-case conviction of Thomas Mitchell Jr. of South Portland, for the murder of Judith Flagg in Farmington in 1983. Computer analysis of sole patterns matched his shoes with a boot print from the scene. A DNA match was the conclusive proof of his involvement, but the shoe match helped confirm him as the prime suspect.

''Anything that leaves a fairly distinctive image can be placed in a database, and these computer gurus can come up with the programs that compare things and the statistics of the quality of a match,'' said Elliot Kollman, head of the state crime lab.

Not surprisingly, computer crimes also are becoming more pervasive. Consequently, a Portland detective who works with the state computer crimes unit will be stationed at the lab to help investigators secure computer evidence for analysis.

Mills said police will have to keep pace with technology to ensure the best results and meet juries' expectations.

''I find that, because of TV shows in recent years, juries tend to expect CSI to be on the scene,'' she said, referring to the popular crime show.

Farrell, who is 82, also toured the new facility Wednesday.

He was impressed by what he saw, but he noted that crime scene analysis still involves a human element -- the steady hand and sharp eye of an evidence technician.

Staff Writer David Hench can be contacted at 791-6327 or at:

dhench@pressherald.comEXAMINING THE EVIDENCE

1) FORENSIC LIGHTING:

USING A COMBINATION OF DIFFERENT WAVELENGTHS OF LIGHT AND SPECIAL GOGGLES, TECHNICIANS ARE ABLE TO SEE EVIDENCE THAT WOULD BE INVISIBLE TO THE NAKED EYE. MINUTE FIBERS, FINGERPRINTS, BLOOD, SEMEN OR OTHER FLUIDS THAT MIGHT CONTAIN DNA CAN BE SUBJECTED TO CHEMICALS THAT ARE THEN ILLUMINATED BY THE SPECIAL LIGHTING.

A PORTABLE VERSION OF THE LIGHT CAN BE BROUGHT TO A CRIME SCENE TO SCAN A ROOM, LOOKING FOR BLOOD, PRINTS OR OTHER CLUES.

2) DIGITAL FINGERPRINT ANALYSIS:

A DIGITAL CAMERA WITH HIGH INTENSITY LIGHTING IS USED IN CONJUNCTION WITH A COMPUTER PROGRAM TO REPRODUCE A BLACK AND WHITE FINGERPRINT IMAGE, REGARDLESS OF THE SURFACE FROM WHICH IT WAS RETRIEVED. THAT IMAGE IS THEN LOADED INTO A COMPUTER THAT IDENTIFIES UNIQUE FEATURES OF THE PRINT AND COMPARES IT TO THOSE IN A DATABASE OF KNOWN OFFENDERS OR OTHER UNSOLVED CRIMES. THE TECHNOLOGY BECOMES INCREASINGLY EFFECTIVE AS MORE FINGERPRINTS ARE ADDED TO THE DATABASE. THE IMAGES ALSO ARE TRANSMITTED TO THE FBI NATIONAL DATA BASE.

3) BIOHAZARD PROCESSING:

BEFORE TRACE EVIDENCE CAN BE RECOVERED FROM MATERIALS GATHERED AT A CRIME SCENE, THE ITEMS MUST BE DRIED. ENCLOSED CABINETS DRAW IN FILTERED AIR AND VENT TO THE OUTSIDE, QUICKLY DRYING ITEMS LIKE BLOODY CLOTHING OR MATERIAL FROM A FIRE. THE LAB CONTAINS SEPARATE BIOHAZARD ROOMS FOR MATERIAL FROM A SUSPECT AND MATERIAL FROM A VICTIM SO THERE IS NO CHANCE OF CROSS-CONTAMINATION.

AFTERWARD, EVIDENCE TYPICALLY IS HEAT-SEALED IN PLASTIC TO PREVENT IT FROM DEGRADING.

4) COMPUTER CRIMES:

ANALYSTS COPY SUSPECTED COMPUTER HARD DRIVES, THEN USE SOPHISTICATED SCANNING PROGRAMS TO SEARCH FOR KEY WORDS INDICATING THE PRESENCE OF CHILD PORNOGRAPHY OR OTHER EVIDENCE, EVEN IF IT HAS BEEN DELETED. THE LAB ALSO CAN DISASSEMBLE AND RESTORE DAMAGED COMPUTERS AS WELL AS ACCESS THE MEMORY STORAGE IN FLASH DRIVES, DIGITAL CAMERAS AND EVEN IPODS.

5) CHEMICALS:

SOME CHEMICALS CAN CLING TO THE SWEAT AND ENZYMES OF A SUBTLE FINGERPRINT. OTHERS REACT WITH BLOOD TO MAKE IT MORE VISIBLE. ACIDS CAN BE USED TO RECOVER THE SERIAL NUMBER OBLITERATED FROM A GUN.

USING A PROCESS CALLED FUMING, EVIDENCE IS SUSPENDED IN A VAPORIZED GLUE-LIKE SUBSTANCE THAT ADHERES TO LATENT FINGERPRINTS. EVIDENCE TECHNICIANS ALSO USE DIFFERENT COLORS AND TYPES OF POWDER TO HIGHLIGHT THE UNIQUE PATTERN OF RIDGES LEFT BEHIND IN THE FORM OF A FINGERPRINT.

THE SUBSTANCES ARE OFTEN HAZARDOUS, SO APPLYING THEM WITHIN A VENTED HOOD IS SAFER FOR INVESTIGATORS.

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