Police forensics are first link in chain of evidence

In Waterloo Region, television fiction mirrors reality with yellow police tape cordoning off a crime scene, cameras flashing and fingerprint dusting equipment put to use.

Working behind the scenes with the minutiae of evidence to solve a case, the Forensic Identification Unit (FIU) of the Waterloo Regional Police Service ply their craft in an area of police work that doesn’t receive much attention from the public—and neither is that attention necessarily wanted.

Access to FIU and its 17 officers, stationed at police headquarters at 200 Maplegrove Road in Cambridge, is tightly controlled. Constable Ray Keenan, who declined revealing his age, has been with FIU since 1989, after 13 years on patrol. A fingerprint expert, he is one of 15 identification officers, along with two Automated Fingerprint Identification System (AFIS) officers in the unit.

The tight access is critical to the work the unit does to ensure that the chain of evidence remains uncontaminated, according to Keenan.

“Our team works impartially with the evidence. The science is not biased. Our findings are replicable and verifiable. We provide the ‘who’ [and] it’s then up to the detectives to determine why the [finger]print was there, and whether it is suspicious. We’re the first link in the chain.”

As Police Week, which took place May 15-21, wrapped up, Keenan said that DNA may be the poster child of forensic identification, but the first fingerprint analysis was used in a criminal trial in 1892. A forensic officer’s choice between using the two techniques could be critical.

“If siblings are identical twins, their DNA is the same. However…fingerprints are individual to each individual. It’s an important distinction. Sometimes we have to decide whether to test for DNA or fingerprints. If we dust for fingerprints, we will destroy the DNA. If we swab for DNA, we will obliterate the fingerprints. If we choose wrong, we have nothing.”

Keenan explains that the basics of fingerprint analysis are straightforward, at least before the officers apply mathematics, chemistry and computer analysis. A member of the identification unit arrives at a crime scene, assesses it, and determines whether fingerprints can be processed at the scene or must go back to the lab. An hour in the field usually requires four or five hours back at the lab to get the identification.

The prints are dusted, processed and photographed at every stage. The best fingerprints are chosen and enhanced for the best resolution before being run through the AFIS system. The computer compares minutiae, the unique whorls, ridges and endpoints, and creates a mathematical algorithm. It then generates a list of potential matches.

Each potential match is then individually analyzed to determine if it is an exact match to the fingerprint, says Keenan who remarks that fingerprints are rarely the quality seen on television crime shows. “I can spend two or three days staring at fingerprints and still not find a match. Other days, it’s the first one I look at.”

Identification is then confirmed by three independent, qualified police officers at the station who verify the identity. “There is no doubt as to the identity of the fingerprint when it leaves the office,” says Keenan.

Constable Keenan watches police shows on television and admits that the "shows are well researched and the methods are accurate. Some of their scenarios are plausible, but the time frames are not realistic. In some ways, the shows have upped the game for law enforcement by revealing some of the ways evidence is gathered and processed. While the criminals know some of the trade secrets from the show and find new ways to thwart the process, law enforcement is still winning."

Innovations in chemistry and the advent of computers have made the job easier, and FIU officers in the law enforcement community are collaborative and share techniques and training.

Among the best parts of Keenan’s job, he says, is the challenge of lifting a useable print. “We operate outside the box. The box is what we keep our tools in.”

While he has enough years of service to retire, Keenan has no plans to do so. “It’s a blast. I like the process of finding what the evidence will tell me.”