By John DiConsiglio
For more than 100 years, fingerprints have been the forensic scientist’s handiest tool. They have been used to catch killers, free the wrongly accused and bring peace of mind to the families of victims. They’ve helped law enforcement link crime scenes, track criminal records and aid in everything from sentencing to pardoning decisions. Lives often hang in the balance of each recovered loop, whorl and arch on a car door, keyboard or coffee cup.
“Latent print examiners have enormous responsibilities. The way they do their job can determine whether someone goes to prison—or worse,” said Edward Robinson, an associate professor in the Department of Forensic Sciences who spent more than 25 years as an investigator for police departments in Arlington, Va., and Baltimore, Md. “But it’s incredibly satisfying because you can really make a difference.”
While loyal CSI watchers can explain how perpetrators’ prints crack cases on TV, Robinson revealed a secret that real forensics experts know all too well: Fingerprints don’t always point to justice being served. An array of factors from weather conditions to human error can mar even the most pristine print. “TV has given us a terribly distorted picture of fingerprints and fingerprint examiners,” he said. The characters in some popular shows “use the wrong instruments, mix up the terminology and even dress better than we do in the lab.”
To dispel this misinformation and meet the growing demand for skilled analysts, Forensic Sciences’ added two new graduate programs this year relating to fingerprint investigation: an MFS in Friction Ridge Analysis and a Graduate Certificate in Latent Print Examination. The programs offer students hands-on experience using state-of-the-art technology like mass spectrometry, digital cameras, forensic instrumentation and the latest in computer programming—a far cry from ancient Babylon where fingertips were pressed on clay tablets to complete business transactions. But since that first recorded use of fingerprints as a means of identification, the basic premise remains the same: Fingerprints are patterns of raised ridges and sunken furrows on the pads of our fingers, palms, toes and the soles of our feet. Their primary evolutionary purpose is to help us grip objects. Each print’s unique patterns—grouped into three general designs called loops, whorls and arches, all in seemingly unlimited combinations of numbers and sizes—lead to their remarkable identification properties.
Latent prints—those not visible to the naked eye—are embedded on surfaces by the pressure of a finger’s touch and the transfer of moisture from our skin. The prints can be revealed by dusting them with black powder or by advanced crime scene technologies like lasers and LED devices.
Since the 1980s, computer databases have enabled law enforcement officials to instantly cross-check millions of collected prints rather than manually checking one at a time. But even computers have limitations. First, there’s no guarantee that the database will actually contain the print an investigator is seeking. “On TV a fingerprint is lifted at a crime scene, fed into a computer and there’s always a direct match to a criminal—and usually a photo,” said second-year forensic sciences graduate student AnniLauri Villeme. “The real-life database [called the Automated Fingerprint Identification System] gives results not just for one individual but for quite a few who have matching fingerprint characteristics.” Second, while a computer may suggest possible candidates, it’s still the examiner and her razor-sharp attention to detail who carefully scrutinizes each edge, ridge and valley for a suitable match—an often painstaking process. “When I was in class comparing prints, sometimes it would take hours just to identify one print,” Villeme said. “But it is absolutely rewarding when you make an identification after hours or days of working on a comparison. It is a true ‘aha!’ moment.”
Indeed, searching for the perfect print match is as futile as hunting the white whale, Robinson said. Nearly all recovered prints are smeared and smudged by everything from the body’s natural oils to grime-covered surfaces. A print can be affected by weather (too hot and perspiration may drown the print; too cold and there may not be enough moisture to leave a mark) and the collection method itself (black powder can clump and obscure ridges). The limitations to fingerprint science often confound students. For example, there’s no scientific way to determine when a latent print was first deposited on a surface. Under the right conditions, prints can survive indefinitely. And it is not possible to determine sex, age or race from a print unless traces of DNA were left behind as well.
“Fingerprints aren’t magic scientific bullets,” Villeme said.
The Myths of Fingerprints
According to Robinson, the following are some of the most common myths relating to fingerprint analysis:
- Fingerprints are forever. Not necessarily. Skin conditions like psoriasis and even genetic factors can either distort or prevent fingerprints from forming in the first place. Tough tactile work like bricklaying can erode fingerprints. And criminals have had varying success with grisly attempts to remove their fingerprints—attacking them with everything from steel files to, in the case of notorious gangster John Dillinger, acid.
- Humans are the only animals with prints. Not true. A few non-human animals have unique fingerprints, including gorillas, chimpanzees and koalas. Koalas prints are so similar to humans’ that even experts have had trouble telling them apart. But with two thumbs on each hand, a koala’s full palm print is unmistakable.
- No two sets of prints are alike. Science has never proven this well-worn assumption—but it hasn’t been disproven either. No two identical sets of fingerprints have ever been recorded, not even among twins or triplets who can share the same DNA patterns.
- In the age of DNA, fingerprints are becoming irrelevant. Actually, fingerprints are still the most frequently found evidence at crime scenes—even more than DNA traces. That’s because most crime scenes don’t have blood and body fluids, but they have been touched by someone
To the latter point, latent prints are still so ubiquitous that crime scene labs are struggling with a shortage of qualified examiners—a need that is being addressed by Columbian College through the new graduate programs in friction ridge analysis and latent print examination “The value of our programs is that students not only learn theory and concepts, they learn practice,” Robinson explained. “If they are asked to recover a print during a job interview—and there's a good chance they will—they can be confident because they have done it before.”