Fingerprint-a globally known word equally with its importance. Every individual owns a unique set of fingerprints. Since the day of great discovery about the uniqueness of fingerprints-This concept became of very great importance among police and forensic professionals. They start to collect the fingerprint from individuals (suspect/victims), crime scenes, and evidences. These records are useful in linking suspects or victims to a crime scene or evidence found from the scene. With this information, a court of law incriminates or exonerates a person.
“Necessity Is The Mother Of Invention”
As time advances, methods of conducting criminal activities and the thought behind them also become innovative. Innovations are also a part of Forensic methods and techniques. One of such techniques is Time Tracing Fingerprinting or so-called Fingerprint Dating.
Fingerprint dating is a method used to determine the time when the fingerprint is placed at a particular item, place, or evidence. It is pretty useful when an investigator wants to know which fingerprint was made on evidence during the time of criminal activity.
Two approaches were made by scientists to explore this technique to determine the age of fingerprints after their uniqueness.
Shin Muramoto and Edward Sisco, NIST (National Institute of Standard and Technology, USA) scientists, were working on trace quantities of drugs in fingerprints but they observed that some chemicals, with the passage of time, were moving away from peaks to valleys of fingerprints. The technique, time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to age fingerprints. Fatty acids (Lipids) are present in fingerprint residue. They notice the migration of fatty acid, Palmitic acid, over time because these molecules are small enough to ionize with TOF-SIMS and are easy to identify.
“We map chemical composition with a submicrometer resolution and look at how the compounds move,” Sisco says. Smaller molecules move faster, heavier ones slower.
The NIST paper only reports on aging fingerprints for up to four days. Sisco said, “you can distinguish between the first day and a week, between a week and a month, between a month and four months.”
Palmitic acid (green) migrates over three days from a fingerprint’s peaks to its valleys.
The second approach also involves biomolecule, Lipid (fatty acids or triacylglycerols). Scientists have found that these biomolecules gradually degrade with time. This is due to their reaction with ozone present in the air.
The technique used by them to notice the level of lipids in fingerprints for a period of 7 days is mass spectrometry imaging.
Researchers use the fingerprints of three individuals and found that the rate of degradation of fatty acids varies among them. This is due to a higher level of lipids in that individual which slowed down the loss of fatty acids.
The researcher claimed that this technique could also be used on prints lifted with fingerprint powder.
In the future, scientists are working on different environmental conditions that affect the degradation of fingerprints and how these rates differ from one person to another.
Hifz Ur Rehman is pursuing his graduation in forensic science from KFUEIT, RYK, Pakistan