The decomposition process in two restricted access environments in a temperate climate: Hard-covered suitcases and wheeled bins

Abstract

The succession, development, and behavior of necrophagous insects on decomposing remains are used by forensic entomologists to estimate the minimum post-mortem interval (minPMI). Carcasses are often recovered from concealed environments, such as burials, wrapping, suitcases and waste bins, where they are protected from abiotic and biotic factors, including carrion fauna. The present study represents the first comprehensive research on concealed environments in Australia. Stillborn piglets (Sus scrofa domesticus L.) placed in hard-covered suitcases (N = 40, restricted access) and wheeled bins (N = 20, partially restricted access) were compared with controls (N = 5, exposed) placed on the soil surface, over a period of 164 days (Austral winter to spring). The analysis compared the decomposition process patterns and considered the insect assemblages colonizing the carcasses in each concealment type and the controls. Results show that 1) insects were attracted to the control carcasses within hours of placement in the field (Day 1, D1), followed by wheeled bin carcasses (D3) and suitcase carcasses (D4); 2) carcasses reached skeletonization on D65 (exposed), D108 (wheeled bin) and D136 (suitcase); 3) the assemblages of necrophagous insect species were different between the exposed and the concealed carcasses; 4) blowflies (Diptera: Calliphoridae) were the most prevalent insects colonizing the controls and wheeled bins, while coffin flies (Diptera: Phoridae) were the most prevalent in the suitcases, with some colonized by black soldier flies (Diptera: Stratyiomiidae). The results of this research contribute to the understanding of decomposition processes and insect activity in restricted access environments and help provide a more accurate estimation of the minPMI in forensic cases.