Four Forensic Entomology Case Studies: Records and Behavioral Observations on Seldom Reported Cadaver Fauna With Notes on Relevant Previous Occurrences and Ecology.

A yearlong survey of insect taxa associated with human decomposition was conducted at the Southeast Texas Applied Forensic Science (STAFS) facility located in the Center for Biological Field Studies of Sam Houston State University in Huntsville, TX. During this study, four insect-cadaver interactions were observed that represent previously poorly documented yet forensically significant interactions: Syrphidae maggots colonized a corpse in an aquatic situation; Psychodidae adults mated and oviposited on an algal film that was present on a corpse that had been recently removed from water; several Panorpidae were the first insects to feed upon a freshly placed corpse in the autumn; and a noctuid caterpillar was found chewing and ingesting dried human skin. Baseline knowledge of insect-cadaver interactions is the foundation of forensic entomology, and unique observations have the potential to expand our understanding of decomposition ecology.

Terrestrial laser scanning and a degenerated cylinder model to determine gross morphological change of cadavers under conditions of natural decomposition.

Decomposition can be a highly variable process with stages that are difficult to quantify. Using high accuracy terrestrial laser scanning a repeated three-dimensional (3D) documentation of volumetric changes of a human body during early decomposition is recorded. To determine temporal volumetric variations as well as 3D distribution of the changed locations in the body over time, this paper introduces the use of multiple degenerated cylinder models to provide a reasonable approximation of body parts against which 3D change can be measured and visualized. An iterative closest point algorithm is used for 3D registration, and a method for determining volumetric change is presented. Comparison of the laser scanning estimates of volumetric change shows good agreement with repeated in-situ measurements of abdomen and limb circumference that were taken diurnally. The 3D visualizations of volumetric changes demonstrate that bloat is a process with a beginning, middle, and end rather than a state of presence or absence. Additionally, the 3D visualizations show conclusively that cadaver bloat is not isolated to the abdominal cavity, but also occurs in the limbs. Detailed quantification of the bloat stage of decay has the potential to alter how the beginning and end of bloat are determined by researchers and can provide further insight into the effects of the ecosystem on decomposition.

Exclusion of forensically important flies due to burying behavior by the red imported fire ant (Solenopsis invicta) in southeast Texas.

On March 3, 2009, the remains of an adult male were partially buried at the Southeast Texas Applied Forensic Science (STAFS) Facility at the Center for Biological Field Studies (CBFS), Sam Houston State University, Texas. The individual was buried except for a small portion of the left abdominal region. A postmortem incised wound was created in the exposed area with the intention of attracting carrion flies. Worker ants of a colony of Solenopsis invicta Buren 1972 (red imported fire ant) filled in the wound with soil, thereby monopolizing the exposed area of the corpse and excluding expected carrion insects from the wound. During the bloating phase, approximately nine days after burial, normal decomposition processes of the gut created a sufficient disruption of the ants, such that flies oviposited and larvae were able to colonize the corpse. Estimation of the postmortem interval (PMI) based on the minimum period of fly activity would be severely skewed should the remains be discovered at this point and growth rate of Diptera larvae be used as the primary determinant for the PMI. While S. invicta is an expected member of a carrion ecosystem in southeastern Texas, and is known to distort the PMI estimation through larval and egg removal, the complete exclusion of flies from the wound by the burial behavior of S. invicta was an unexpected and until now an unpublished occurrence.