How to Catch a Criminal Using Their 'Skin Shedder' Profile?

In forensic science, "touch DNA" has proved to be a central method of identifying suspects. All human beings involuntarily shed skin cells wherever they come into contact, depositing extremely tiny biological traces behind them. Fresh trail-blazing research is describing how people vary in the amount of skin and cell DNA they shed, often referred to as their "shedder" profile, and how this information can aid criminal investigations.

What Is a 'Skin Shedder' Profile?

Scientists have discovered that individuals shed skin cells and DNA at incredibly variable levels. Some individuals are "high shedders," leaving copious skin cells on surfaces they come into contact with, while other individuals are "low shedders," leaving fewer cells. This range affects the detection and identification of DNA evidence that is gathered at crime scenes.

Groundbreaking researchers at Flinders University in Australia have developed a powerful scientific method to measure the "shedder status" of a suspect using a novel cell staining method. In a trial on 100 individuals, they confirmed that each person always sheds the same number of skin cells regardless of sampling time, and that men shed more cells than women. The important thing is that it does not matter which hand an object is held in—shedding is symmetrical either way.

Why is 'Shedder Status' Important in Forensics?

Traditional DNA profiling can identify whether a person's DNA has been present but not why or how it was present. For instance, an identification of a suspect's DNA on the scene of a weapon can be challenged if the person says they only briefly touched the object or was not involved in a crime.

A suspect's shedder profile is useful information. If you are a high shedder, it is easy to transfer your DNA, and it would account for DNA found at a place where you did not extensively touch. Low shedders, on the other hand, would not leave significant DNA where they extensively handled items. This provides forensic specialists with the ability to estimate the probability of DNA presence using a "likelihood ratio," providing courts with more precise evidence of a suspect's involvement in a crime.

This study is particularly useful in identifying suspects and cracking cases in which "competing DNA evidence" previously muddled investigations.

New Developments in Skin and Touch DNA Profiling

In addition to the quantitation of shedder status, forensic scientists are also developing accurate detection of skin cells themselves. Skin cell-specific messenger RNA (mRNA) markers have, for the first time, been detected, enabling tests to determine whether DNA recovered from samples specifically derives from skin. This method, reported in forensic biology journals, increases accuracy in the identification of biological material, differentiating skin from other body fluids and tissues.

Additionally, new studies target structural proteins and carbohydrate marks on skin cells, improving detection of latent "touch DNA" on surfaces, after prolonged outdoor exposure.

Real-Life Applications and Future Applications

Knowing and using "skin shedder" profiles can:

• Help reduce investigation times by concentrating on suspects that have similar DNA profiles to shedder patterns.
• Help reduce false accusations due to DNA contamination or secondary transfer.
• Help forensic specialists by giving an extra strong layer of evidence to utilize in supporting or disproving assertions.
• Assistance in the quantification of the amount of time a suspect could have spent at a crime scene using cell deposition counts.

Furthermore, while promising, there remains improvement to be made in refining these methods. Further research is ongoing to determine best practices for the inclusion of shedder status within forensic casework globally. 

The science of "skin shedder" profiling is an exciting new frontier in forensic investigation, combining biology and law enforcement with precision. Understanding how individuals uniquely shed skin cells and DNA, forensic examiners can more accurately interpret DNA evidence, catch criminals more effectively, and ensure justice is meted out. 

For students and practitioners alike who are interested in forensic science, staying current with these cutting-edge advancements is a window into the future of crime-solving technology.