GENETIC IDENTIFICATION OF BURNED HUMAN REMAINS IN A VEHICULAR DISASTER CASE

TERCER LUGAR: TRABAJO LIBRE SOMETIDO EN LAS XV JORNADAS LATINOAMERICANAS DE GENETICA FORENSE DE LA SLAGF, BOLIVIA 2025

Abstract

Objective: Identifying burned remains in a vehicle accident on the Desaguadero Highway, La Paz, Bolivia.

Introduction: Genetic identification of burned remains (tissue, bones, or teeth) is challenging because the recovered DNA is often degraded or contaminated by foreign DNA (1). This recovery is crucial for individual identification and the return of remains to their families, becoming an ethical and technical standard of forensic practice.

Methods: Burns were classified according to Schwark et al., 2011. (Table 1). The burned skeletal remains were cleaned with sodium hypochlorite and UV irradiation, and pulverized in liquid nitrogen. The phenol/chloroform/isoamyl alcohol (24:24:1) method was used for DNA extraction. A modification of the Wizard Genomic DNA Purification Kit (Promega) was used for burned muscle tissue and swabs. The DNA IQ Reference Sample Kit (Promega) was used for reference samples. STR characterization was performed with the Identifiler Plus and Y-Filer kits, and mitochondrial DNA analysis of hypervariable regions I and II was performed with the BDT 3.1 kit (Applied Biosystems).

Results: The remains analyzed (Table 1), complete autosomal, Y chromosome, and mitochondrial profiles were characterized. These were matched to the families of the victims, with the exception of corpse F. One family did not match any of the corpses studied.

Discussion: Combined analysis of mitochondrial DNA and STRs allowed the identification of burnt remains despite degradation, using optimized methods such as phenol-chloroform and Wizard Genomic, although the complete carbonization of tooth E3 and the non-correspondence of corpse F reflect the challenges of degradation and contamination pointed out by (2).

Conclusion: Family link reconstruction shows that families 1, 3 and 5 are related to corpses A, D and B, (LR= 1.3442E+12; 1.3960E+09 and 3.6940E+13), family 2 is related to corpses G (LR= 1.0539E+06) and H (LR= 1.0258E+04), families 4 and 6 are related to corpses E and I (LR= 3.8205E+04 and 2.1320E+04); in addition, mitochondrial DNA analysis revealed that corpses B, E, G-H, I and F share the same maternal lineage with the families described above (LR=175), with the profiles being more likely to match if they come from the same maternal line than if they are from unrelated individuals. Corpse F does not correspond to any family analyzed (LR=4.3196, with family 7), and family 7 has no associated remains.