Impact of sample degradation and inhibition on field-based DNA identification of human remains

Abstract

The advent of DNA technologies for field-based application promises to provide rapid intelligence to aid investigations. Their validation and adoption by enforcement groups have demonstrated utility in sample screening and prioritisation, but field application in some areas of forensic science, such as human remains identification, is little evidenced. Assessing the ability of such approaches to provide meaningful data is critical as decomposition is likely to complicate analysis and limit the effective use of such field-based DNA interventions. This research assessed the ability to collect viable DNA data in the field using the ParaDNA Field Instrument and Intelligence Test chemistry. Different sample collection methods were assessed; direct from skin surface; direct from exposed tissue; indirect from muscle swab transferred to FTA card; and from larvae on the donors. Samples were collected and processed on-site at the Anthropology Research Facility, University of Tennessee. The data show that the muscle tissue provided the most effective sample template and, using this approach, it was possible to generate STR profiles from human remains in under two hours from the time of sample collection. STR profile data were collected up to four days from donor placement (114 Accumulated Degree Days). After this time there was a rapid decrease in the quality of the profiles collected due to the onset of decomposition. The data also show that effective sample recovery was not possible from the surface of the skin, exposed tissue or from carrion larvae. Inhibition studies in the laboratory suggest that by-products of the decomposition process are the primary mode of failure. Together these data suggests a possible application for screening and prioritisation in criminal casework but highlights issues that may affect the success of the approach.

A Systematic Review on Commercially Available Integrated Systems for Forensic DNA Analysis

“…They valued the possibility of performing rapid processing in the field with the ParaDNA system. However, further optimization is required concerning the collection process in the case of human remains [ 45 ].…”

“…In conclusion, the ParaDNA Screening System can be used for samples that contain a relatively high amount of DNA, such as blood, saliva, and semen [ 38 , 39 , 40 , 43 ]. Since only 6 STRs (or less for some kits) are analyzed, the ParaDNA system can only be used for screening and indicative testing, which is a limitation of this system [ 45 ].…”

DNA Transfer in Forensic Science: Recent Progress towards Meeting Challenges

“…Two studies also investigated the use of non-traditional DNA profiling systems, specifically field-based systems and Massive Parallel Sequencing (MPS). While rapid field-based DNA identification systems have their benefits, Dawnay et al [113] illustrated the limitations of the ParaDNA Field Instrument and Intelligence Test Chemistry (LGC) to collect viable DNA samples and produce profiles from the surfaces of the skin, exposed tissue or carrion larvae. The use of MPS in comparison to traditional Capillary Electrophoresis (CE) techniques to generate DNA profiles from real casework samples obtained from semen, saliva, blood, and epithelial material on various surfaces, as well as reference oral swabs, was evaluated by Avila et al [114].…”

Revolution in death sciences: body farms and taphonomics blooming. A review investigating the advantages, ethical and legal aspects in a Swiss context

“…Following the localization step, the identification is crucial in forensic cases. To this end, studies in HFTF allow the development of new protocols to collect genetic information [198][199][200].…”