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Isotopes Aiding Identification of Undocumented Border Crosser Human Remains
Wednesday, February 6, 2019 5:45:00 PM UTC - 7:30:00 PM UTC
Duration: 1 hour(s) 45 minute(s)
This webinar highlights the theory and methods of isotopic analysis to explain how it can be used to assist in the identification of human remains for undocumented border crossers who do not survive the journey between Mexico and the United States.
Since 1998 more than 7,000 people have lost their lives trying to cross the border from Mexico into the United States. Each year, the remains of hundreds of individuals are found and more are being excavated because they had previously been buried without full examination. Hundreds of these individuals remain unidentified after traditional identification methods have been exhausted. This presentation will explain how isotopes can be potentially of use when trying to identify undocumented border crossers for whom other methods have not yielded an identification. 

Isotopes can aid in the prediction of past places of residence and past human diets using chemical signatures in human remains, including teeth, bone and hair, which are focus of this research. Different tissue types form in the body at throughout a person’s life providing a record of past diet and residence.  For example, teeth formation in childhood can provide a chemical signature at the time of formation that remains with a person even though the teeth do not erupt until much later. By contrast, hair is continually being formed, and therefore, provides a record of a more recent diet and place of residence. 

Isotope analysis has become a more integral part of forensic casework, for example, authorities can gain additional information on cold cases, as well as, determine the origin of materials involved in a crime. However, determining the past residence of an individual is only possible if there is knowledge of the isotopes in the environment of the region.  The development of regional maps of the distribution of isotopes is therefore required, and this is done based on water and geological samples to produce “isoscapes”. The isotope landscapes are models or spatial observations of the variation in isotope ratios. Isoscapes are well established in the United States but are lacking in Mexico and Central America. This research project aims to close this gap by creating isoscapes from Mexican tap water samples as well as modern human hair from individuals residing in Mexico. Furthermore, and this webinar will explain the methods used to set up new isoscapes.  It moreover discusses the analyses currently being conducted on the unidentified skeletal remains of undocumented border crossers. 

Ms. Ammer wrote the AAFS HHRRC grant that funded this project and was fortunate to be able to work with the Pima County Office of the Medical Examiner, volunteer with the Colibrí Center of Human Rights and coordinate with approximately one hundred people donated hair samples in Mexico for this project. While the US-Mexico border is a much-discussed topic, the fate of the undocumented border crossers who do not survive the journey through this rough terrain is rarely the subject of conversation. This presentation will conclude with a brief discussion of the implications of this type of work and how it can be further advanced. 

Detailed Learning Objectives:

•	Understanding the role of isotope analysis in forensic anthropology and the implication in identification efforts of unidentified individuals.

•	Illustrating the importance of a collaborative approach and how each entity furthers the identification process. 

•	Discussing the challenges faced in isotope analysis and in the identification effort of undocumented border crossers.

Funding for this Forensic Technology Center of Excellence event has been provided by the National Institute of Justice.


Saskia Ammer
Anthropology PhD Candidate at the University of Coimbra in Portugal. She focuses on forensic anthropology and the use of isotopes to predict residence patterns and human diet using chemical signatures in human remains. For this project, she traveled from Cancun to Tijuana to collect reference samples that represent the isotopic environment of Mexico....