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A DNA Barcoding Strategy for Blow and Flesh Flies Encountered during Medicolegal Casework

NCJ Number
309831
Author(s)
Date Published
July 2022
Length
22 pages
Annotation

In this paper, researchers introduce a DNA barcoding strategy for blow and flesh flies encountered during medico-legal casework.

Abstract

In this project, researchers worked to develop and validate an optimized DNA barcoding strategy for identifying blow, flesh, and scuttle flies commonly encountered in forensic entomology casework. Approximating time since colonization of human remains by local fly populations is considered one of the most accurate methods for estimating post-mortem interval during medicolegal death investigations. A key requirement for estimating PMI is that the species of each specimen under consideration must be determined since colonization and developmental timelines vary between fly species. Species determinations are performed by identifying distinct morphological characteristics as indications of particular taxonomic groups. Limitations to this process include that recognizing species-specific morphologies requires specialized knowledge and expertise in the field of entomology. The purpose of the current work is to develop and conduct internal validations for the method so that it may be applied to death investigations. This tool may also be used for academic studies of regional populations comprising species that overlap with this study. This work additionally discusses means for improving the quality and accuracy of the results. Completion of this project will further the application of forensic entomology by HCIFS Forensic Genetics Laboratory and Medical Examiner Services. The tool may be useful to other organizations since the species relevant to the region are widespread in the United States. A formal validation was completed for the COI barcoding method during the reporting period. Experiments were performed in accordance with the FBI Quality Assurance Standards for Forensic DNA Testing Laboratories and ISO/IEC 17025 International Standards. Detailed reports were produced that documented findings from each experiment conducted during validation. Standard operating procedures were produced encompassing the entire process as guidance for analysts (DNA extraction, PCR purification, gel electrophoresis, and interpretation of Sanger sequencing data).

Date Published: July 1, 2022