Forensic entomology currently represents a precise and accurate approach for estimating the minimum postmortem interval (PMIMIN) in medicolegal death investigations. However, this field would greatly benefit from baseline data regarding the early stages of body exposure before insects arrive (the pre-colonization interval or pre-CI) to further refine PMIMIN estimations. The goal of this project was to generate a human-specific pre-CI baseline dataset covering a range of ambient temperatures. Donated human remains (N = 62) were placed at the University of Tennessee Anthropology Research Facility across all seasons over a 3-year period and allowed to be colonized naturally by local blow flies. Initial oviposition events were recorded, and insect eggs from a subset of donors were reared for species identification. Ten donors were randomly selected to constitute the first validation cohort, using the remaining 52 donors as the training dataset. A second validation cohort consisted of 13 additional donors with unknown pre-CI data. The most important pre-CI predictors were statistically grouped, and a 95% confidence interval was determined. Minimum temperature was found to be a statistically significant predictor of the pre-CI (p = 0.000, R2 = 0.608), and the pre-CI dataset produced accurate estimations for samples collected above a minimum daily temperature of 22°C. The addition of the pre-CI to larval age estimations significantly improved estimation accuracy (χ = 106.19, df = 4, p < 0.001). The generation of an error rate for this time interval aligns with the recommendations for strengthening forensic science set forth by the National Research Council.
Owings et al. (Thu,) studied this question.