Subaerial Decomposition of Small-Sized Remains in The Netherlands: Important Findings Regarding the PMI of a Four-Year Taphonomic Study

Abstract

Studying post-mortem changes based on signs of decomposition (e.g., using scoring models) is one of the methods used in scientific studies to relate observable changes to the post-mortem interval (PMI). The majority of the studies on cadaver decomposition are based on large cadavers. There is limited literature on the decomposition pattern and rate of small cadavers, even though it is at least as important to be able to estimate the PMI for infants and subadults. Therefore, it is crucial to acquire knowledge of the decomposition process of child-sized remains. To fill this knowledge gap, a season-based subaerial outdoor decomposition study was conducted with small pig cadavers at the Forensic Anthropological Outdoor Research Facility located in Den Ham, The Netherlands, over a period of 4 years. Den Ham is located in the eastern part of the Netherlands, close to the German border, and has a temperate maritime climate, with a Cfb classification according to the Köppen-Geiger system. Salient findings were acquired during the decomposition study, specifically regarding a deviating decomposition rate during winter and the subsequent spring, reproducibility, the effect of body weight, post-mortem movement, the effect of heavy rainfall on insect activity, delayed bloating, the interaction of different insect species, and invertebrate activity. This article includes a systemic review of the results obtained during this four-year decomposition study and discusses the impact of the findings on the estimation of the PMI.

Keywords: The Netherlands; forensic taphonomy; post-mortem interval; seasonal decomposition; small-sized piglets; subaerial decomposition.

Figure 1

The Forensic Anthropological Outdoor Research Facility Den Ham. The left figure shows where the research location is situated. The figure on the right shows the average sunlight distribution at the research location. The pathway is also shown, around which the cages with pig cadavers were placed.

Figure 2

Visual appearance of pig cadavers: (A) pig cadaver, winter season 38 days post-mortem, which is in the stage of active decomposition; (B) pig cadaver, winter season 92 days post-mortem, which is in the post-active stage; (C) pig cadaver, spring season 38 days post-mortem, which is in the post-active stage.

Figure 3

Mean Total Body Score (TBS) for the winter and spring seasons versus time (n = 2 per season). (A): Research years 2015–2016 weight category 1 (800–2700 g). (B): Research years 2015–2016 weight category 2 (4230–10,500 g).

Figure 4

Total Body Score of the pig cadavers against the number of days post-mortem, where all research years are shown (n = 2 per season), to show the progress in decomposition. (A): Spring season weight category 1. (B): Spring season weight category 2.

Figure 5

Post-mortem movement observed in a pig cadaver in the autumn season, as indicated by the red arrows. (A) Position of cadaver the same as when placed, 21 days post-mortem. (B) Left forelimb has migrated overhead, 28 days post-mortem. (C) Leg remains in this position until the final stage of decomposition is reached, 36 days post-mortem.

Figure 6

Heavy rainfall affected the maggot activity of an autumn cadaver of 2015, resulting in stopped maggot activity and a delay in decomposition rate.

Figure 7

(A) An example of the skin lesions caused by the wasps, in which the flies laid eggs. Here you can see a cadaver of the spring of 2015 (category 1), four days post-mortem. (B) An example of the slugs that were present on the cadavers. Here you can see a cadaver of the summer of 2015 (category 1), two days post-mortem. (C) An example of the slugs that were present on the cadavers. Here you can see a cadaver of the summer of 2018 (category 1), one day post-mortem.