Exposing Fingerprints

Fingerprint

 

During July, the University of Leicester Press Office posted a report about a new technique for visualizing latent fingerprints from crime scenes. Visualizing usable latent fingerprints poses a challenge; about 10% of crime scene fingerprints have sufficient quality to be used as evidence during a trial.

The new technique exposes fingerprints by using the electrically insulating properties of a fingerprint’s sweat and oil deposits. The chemicals in a fingerprint block an electric current used to deposit a colored, electro-active film. The deposited film collects on the surface between fingerprint deposits to create a negative image of the fingerprint. The technique is very sensitive and can be used in combination with traditional visualization techniques, such as fingerprinting powders.

“By using the insulating properties of the fingerprints to define their unique patterns and improving the visual resolution through these color-controllable films,” said team leader Professor Robert Hillman in a press release, “we can dramatically improve the accuracy of crime scene fingerprint forensics. From the images we have produced so far, we are achieving identification with high confidence using commonly accepted standards.”

 

Snacking with Conviction

Food behind bars

 

When criminals snack at a crime scene, they leave evidence behind. A bitemark in half-eaten food is one type of evidence. Peckish criminals also leave DNA and fingerprints.

Last week, Ryan Pfeil of the Medford Mail Tribune (Oregon) reported that burglary is a thirsty business. Burglars broke into a house through a garage and stole a flat-screen television, jewelry, and other valuable items. The burglars also took a container of orange juice from the refrigerator, drank from it, and left the container in the garage on their way out. Investigators sent the container to the Oregon State Crime Lab for tests.

Lab techs found DNA and fingerprints on the carton. They also found a match between one DNA sample and a DNA profile in the FBI database. The DNA match led investigators to a 33-year-old man who faces charges of first-degree theft, aggravated theft and burglary.

Around the same time, forensic scientists at the University of Abertay Dunde (Scotland) announced that they recovered latent fingerprints from foods.

“Although there are proven techniques to recover fingerprints from many different surfaces these days, there are some surfaces that remain elusive, such as feathers, human skin, and animal skin,” former crime scene examiner Dennis Gentles explained. “Foods such as fruits and vegetables used to be in that category, because their surfaces vary so much – not just in their color and texture, but in their porosity as well. These factors made recovering fingerprints problematic because some techniques, for example, work on porous surfaces while others only work on non-porous surfaces.”

University scientists overcame the problem by modifying a technique designed to recover fingerprints from the sticky side of adhesive tape. You can learn more about this breakthrough at the Abertay University website.

 

Scanning for ID

 

MorphoIdent

MorphoIdent™. Copyright ©2009 MorphoTrak Inc. All rights reserved.

 

 

Morpho (Safran group) recently announced the FBI’s certification of the company’s compact high speed livescan fingerprint scanner, the MorphoTop™ Model 100R. Designed for civil applications, the device provides high speed imaging of fingerprints for background checks, travel ID verification, and other uses.

The company’s handheld MorphoIDent™ was designed for use by government officials, such as police and Border agents. This fingerprint scanner offers real-time fingerprint identification by connecting with the Automated Fingerprint Identification System (AFIS) database.

Unless your mystery/crime story takes place in the past, you should consider equipping your fictional law enforcement officers with a fingerprint scanner.

Fish Finger

Fingerprint

 

During September, Nolan Calvin and Mark Blackstone went fishing at Priest Lake, Idaho. They were cleaning a trout when they discovered something unusual: a human finger. The fisherman placed the finger on ice and brought the digit to a local police station. Investigators obtained a fingerprint from the finger; it belonged to Hans Galassi, who had lost the fingers from his left hand during a wakeboarding accident in June. Galassi had no use for the retrieved finger.

As BBC News notes in the article, “Who What Why: How durable is a fingerprint?” fingerprints can last a long time and are tough to get rid of. The article is a good source for basic information about the durability of fingerprints and attempts to obliterate those pesky friction ridges.