The Council for Scientific and Industrial Research (CSIR) has launched a new fingerprinting acquisition system that uses high-speed, large-volume optical coherence tomography (OCT).

In practice, the system, once operational, should see the immediate on-site scanning and matching of fingerprints – also partial prints – found at crime scenes.

Current technology allows for the dusting, lifting and eventual matching of fingerprints. However, CSIR novel laser sources group senior researcher Ann Singh explains, this rather slow, dirty process could destroy DNA evidence linked to the fingerprint, such as blood and sweat. It is also two dimensional.

With the OCT system, the print is scanned, without any contact, and immediately compared with the fingerprint databases used by law enforcement agencies.

The quality of the three-dimensional print captured by the OCT system is also far superior, compared with those lifted by traditional methods, says Singh.

It will still, however, be some time before the system can be used by the South African Police Service (SAPS).

To date, Singh and her team have managed to lift fingerprints from plastics and glass, and match them to prints on the databases used by the SAPS. The next step is to secure fingerprints from highly reflective surfaces, such as metal, as well as from wood.

It is also necessary to make the OCT system, currently roughly the size of two to three shoeboxes, smaller and portable, for use at crime scenes. It is also important to reduce the manufacturing costs.

“The ultimate goal is for real-time fingerprint matching with the database, from any crime scene,” says Singh. “We think we may have something portable in three years.”

She does not foresee any challenges with South African courts accepting the OCT technology, once in use by the SAPS.

Other Applications
The OCT system also has applications beyond forensics.

There are two possible fingerprint capturing processes, explains Singh. The first is live, where someone will typically scan their fingerprints for a new passport at the Department of Home Affairs. The other is latent, such as capturing a fingerprint at a crime scene.

The OCT system allows for the live capture of an internal as well as an external fingerprint. The external fingerprint is the more visible outer layer of skin. The internal fingerprint is less visible, and lies deeper, underneath skin damage or scarring, which makes fingerprints captured by the OCT system much more tamperproof.

It may sound like an episode of CSI, but it is possible to use a piece of sellotape with someone else’s fingerprint on it to gain access to an area protected by a fingerprint scanner, says Singh. However, an OCT system will pick up the anomaly between the sellotape fingerprint and the fingerprint of the person wearing the tape, as well as the fingerprint originally captured, she notes.

OCT scanning can also detect if the subject being scanned is alive or dead.

All these facts hold significance for high-end security applications, such as military security.

The contactless OCT system also makes it possible to scan a live fingerprint without ‘slapping’ down the fingers on paper or glass, which often creates distortion.

“At the end [of the day], the result is a significantly more accurate fingerprint representation,” says Singh.

Singh is a physicist. She graduated at the University of KwaZulu-Natal.