Decomposition patterns of buried remains at different intervals in the Central Highveld region of South Africa

Abstract

Burial of remains is an important factor when one attempts to establish the post-mortem interval as it reduces, and in extreme cases, excludes oviposition by Diptera species. This in turn leads to modification of the decomposition process. The aim of this study was to record decomposition patterns of buried remains using a pig model. The pattern of decomposition was evaluated at different intervals and recorded according to existing guidelines. In order to contribute to our knowledge on decomposition in different settings, a quantifiable approach was followed. Results indicated that early stages of decomposition occurred rapidly for buried remains within 7-33 days. Between 14 and 33 days, buried pigs displayed common features associated with the early to middle stages of decomposition, such as discoloration and bloating. From 33 to 90 days advanced decomposition manifested on the remains, and pigs then reached a stage of advanced decomposition where little change was observed in the next ±90-183 days after interment. Throughout this study, total body scores remained higher for surface remains. Overall, buried pigs followed a similar pattern of decomposition to those of surface remains, although at a much slower rate when compared with similar post-mortem intervals in surface remains. In this study, the decomposition patterns and rates of buried remains were mostly influenced by limited insect activity and adipocere formation which reduces the rate of decay in a conducive environment (i.e. burial in soil).

Where Did They Come from—Multi-Drug Resistant Pathogenic Escherichia coli in a Cemetery Environment?

“…Therefore, this could explain the low number of positive borehole samples and the low mean bacterial count in the positive ones compared to surface water samples. Furthermore, although the decomposition rate of buried cadavers may vary depending on numerous factors, including the presence of a coffin, prevailing temperatures or the presence of clothing on the cadaver, a study in South Africa indicated that cadavers could attain a well-advanced decomposition rate after ±90–183 days following interment [ 36 ]. Furthermore, it has been shown that although the microbial population in decomposing bodies may increase over time, there is a decrease in diversity, especially in the gut microbiome, with Clostridia becoming more common due to their ability to withstand the harsh conditions accompanying decomposing cadavers [ 37 ].…”

Characterizing forensically important insect and microbial community colonization patterns in buried remains

“…However, the majority of these experiments used exposed carcasses of mice 11 , 45 , 48 , humans 11 , 41 , 44 , 47 , 100 , 101 , or swine 31 , 40 . An exposed carcass can differ in many ways including the depositional environment and the decomposer communities and colonizers involved in decomposition, both of which can impact the rate of decomposition and PMI estimation 29 .…”

“…Several other investigations on the decomposition process of buried remains have been reported from Great Britain 12 – 17 Poland 18 , Australia 19 , Argentina 20 , United States of America 21 – 25 , Canada 26 , 27 , Germany 28 , and South Africa 29 . Most of them used human cadavers 17 , 20 – 23 , 26 , 27 and pig carcasses 13 , 14 , 18 , 24 , 25 , few used juvenile rat 19 and sheep carcasses 12 as experimental models, but lacked the combined bacterial and insect community analyses.…”

“…Of these factors, temperature variation plays an important role in carcasses decomposition, with the range of 20–40 °C optimal for tissue degradation 29 , particularly 37 °C 36 . Temperatures below 10 °C and over 40 °C will potentially inhibit decomposition 30 .…”

Inaccuracy of accumulated degree day models for estimating terrestrial post-mortem intervals in Cape Town, South Africa

“…Using this method, approximately 80% of the observed variation in the decomposition process was attributable to thermal energy, measured by 'accumulated degree days (ADD)' --the sum of thermal energy accrued over a period of time. This quantitative method of predicting the PMI based on the visual assessment of decomposition and its relationship to temperature has since become one of the most commonly used approaches for researchers and law enforcement personnel worldwide [2][3][4][5][6][7][8][9][10][11]. However, several studies have reported results that differ significantly between the actual ADD and calculated ADD based on TBS values [5,8,12,13].…”