Can Isotope Detection Locate a Person?

Isotope analysis is one of the most useful techniques available to forensic scientists. Traditionally, the method is used to analyse explosives and determine whether samples the same origin. Most explosives contain a unique mix of carbon, nitrogen, hydrogen and oxygen atoms. Comparing concentrations allows forensic scientists to match samples and detect similarities.

More recently, isotope detection has been utilised as a tool to identify missing persons. While the technique can’t be used to track the location of a suspect or criminal, it’s extremely useful for analysing human remains and identifying unknown persons. When used alongside other techniques such as forensic palynology, isotope detection can help strengthen cases and hold criminals accountable. 

What is isotope analysis?

Before we get stuck into the role isotope analysis plays in forensic science, let’s take a moment to define exactly how the technique works. All materials have a unique chemical signature determined by ratios of different isotopes. British radiochemist Frederick Soddy coined the term “isotope” in the 1900s and used it to describe elements that exist in multiple forms.

Isotopes share the same number of protons though have a different neutron count. It’s this difference in neutrons that sets isotopes apart. Isotope analysis is used to uncover the unique chemical signature of materials and gain insight into the origins of a sample.

Isotope detection in forensic anthropology

In an article published in the journal Forensic Sciences Research, the authors explore the growing role isotope analysis is playing in forensic anthropology casework. Using next-generation analytical standards and instrumentation, isotope detection is being used to unlock additional data for human identification. This includes information about possible region of birth, as well as travel history, diet and lifestyle choices. Many forensic labs also rely on state-of-the-art, AI-powered analytics solutions. 

“Modern-day isotopic investigations on human remains have integrated the use of multi-isotope profiles (e.g. C, N, O, H, S, Sr, and Pb) as well as isotopic landscapes (“isoscapes”) from multiple body tissues (e.g. teeth, bone, hair, and nails) to predict possible region-of-origin of unidentified human remains,” write the authors.

Solving crimes with isotope detection

A technique called isotope fingerprinting can be used to analyse single strands of human hair determine the location of a person over the past few weeks, and sometimes years. This type of geographical tracking can be invaluable when it comes to solving murders. It’s founded on the principle that hydrogen is made up of two stable isotopes while oxygen has three. The “isotopic signatures” of these stable isotopes can vary significantly depending on the source.

The limits of isotope detection

Unlike DNA analysis techniques, isotope detection doesn’t offer absolute certainty when it comes to identifying individuals. For this reason, it’s not always used as court evidence. Though it can be extremely useful when solving crimes.

Isotope detection is one of many breakthroughs revolutionising forensic science. Find out more about other exciting developments, including forensic palynology, DNA sequencing and forensic glass analysis with LA-ICP-MS in ‘8 Advances in Forensic Science’.