Forensic stable isotope signatures: Comparing, geo‐locating, detecting linkage

Abstract

Stable isotope signatures or profiles of physical evidence such as illicit drugs, explosives or human tissue provide information on source, origin, even sample history not obtainable by traditionally applied analytical techniques of forensic chemistry. The discriminatory power, calculated as random match probability, of multivariate stable isotope signatures able to distinguish two cocaine samples from different regions in Colombia can range from one in tens of thousands to one in several million if based on the stable isotope abundances of carbon, nitrogen and hydrogen or carbon, nitrogen, hydrogen and oxygen, respectively. Stable isotope signatures of physical evidence have therefore at the very least great potential to provide invaluable forensic intelligence for intelligence led policing. They may even be of great evidentiary value, especially if corroborated by results from independent analytical techniques. This review aims to offer a glimpse into the fascinating world of forensic stable isotope analysis by discussing the various levels of information stable isotope signatures can provide. For reasons easily appreciated, only a select few instances of its application to criminal investigations have been reported in scientific journals thus far. The various applications of this technique presented in this review are therefore predominantly taken from peer‐reviewed work published in scientific books and journals. This article is categorized under: Forensic Biology > Interpretation of Biological Evidence Forensic Chemistry and Trace Evidence > Explosive Analysis Toxicology > Drug Analysis

Assessing the Reliability of Mobility Interpretation From a Multi-Isotope Hair Profile on a Traveling Individual

“…Some keratinous tissues, like hair and nail, preserve the regional isotopic values in time sequence, and may thus be used to reconstruct the travel history of individuals (Fraser et al, 2006;O'Brien and Wooller, 2007;Hobson et al, 2010;Remien et al, 2014). With increasingly available isoscapes-"isotope land-scapes" or the maps of the spatial isotopic variation of the material(s) of interest (e.g., West et al, 2010)-for more elements and more regions, studies on the isotopic profiles of multiple elements are getting more attention in forensic sciences, archeology, and ecology (Lehn et al, 2011(Lehn et al, , 2015a(Lehn et al, ,b, 2019Thompson et al, 2014;Meier-Augenstein, 2019).…”

Multi-isotopes in human hair: A tool to initiate cross-border collaboration in international cold-cases

“…The isotope delta values are typically reported in permil (‰), with an extraneous multiplication factor of 1,000 sometimes appearing in the equation [6]. Stable isotopes are ubiquitous intrinsic markers with the potential to contribute new and actionable evidence in cold-cases, even those involving long-term unidentified individuals [7][8][9][10][11][12][13][14][15][16][17]. Isotopes compose all organic molecules and their abundances in human tissues inform about a person's diet, health, or mobility history providing critical information about human remains [7,10,16,[18][19][20][21][22].…”

Carbon and nitrogen isotopic analysis of morphine from opium and heroin samples originating in the four major heroin producing regions

“…IRMS has been utilized to help differentiate a wide range of natural materials including food and beverages, [7][8][9][10][11] as well as synthetic and semi-synthetic drugs of forensic interest. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] This laboratory was involved in the initial proof of concept study to geo-source cocaine and heroin using IRMS focusing on authentic cocaine and heroin samples 12 and has continued to incorporate new samples as they become available. Additional research has expanded to the use of radiogenic strontium isotope analyses but has yet to be applied routinely to samples at our laboratory.…”