Predictive Models as Screening Tools for DNA Recovery from Baked and Burned Porcine Bones

Burnt bones and skeletal remnants continue to challenge the proficiency of forensic investigations in human individualization and identification. The various natural disasters and human inflicted crimes involving fire leave the forensic investigators with very little to work on. Thus, demand for practical studies to obtain useful facts for improvisation of current techniques and to overcome the short comings is a prerequisite. In this study Design of Experiments (DOE) as an investigative and screening tool to relate the different variables (burning temperature, time, thickness of flesh, presence of accelerants) involved in the burning process and to detect the probability of obtaining successful DNA identification from burnt bones is proposed. We show that high temperature and large base pair PCR primer have a significant effect on DNA retrieval and amplification. The baking study provides reproducible DNA identification with maximum retrieval temperature of 320°C for the smallest (106bp) amplicon. The study involving accelerants demonstrates that those with high specific heat capacity decrease DNA recovery, hence suggesting probable damage to DNA. Through this study the positive effect of presence of flesh for DNA recovery was also verified with a maximum DNA recovery temperature of 500°C. Utilizing all these information through DOE, predictive models were also created with regression equations to calculate positive DNA amplification and to predict the different variables respective to the burning process. These models created using porcine bones could be related for real scenarios and with more data procurement it could be used effectively in forensic investigations.