Sequential monitoring of burials containing large pig cadavers using ground-penetrating radar

Ground-penetrating radar (GPR) was used to monitor 12 pig burials in Florida, each of which contained a large pig cadaver. Six of the cadavers were buried in sand at a depth of 0.50-0.60 m, and the other six were buried at a depth of 1.00-1.10 m and were in contact with the upper surface of a clay horizon. Control excavations with no pig internment were also constructed as blank graves and monitored with GPR. The burials were monitored with GPR for durations of either 12-13 or 21-21.5 months when they were then excavated to correlate the decomposition state of the cadaver with the GPR imagery. Overall, cadavers in sand were easily detected for the duration of this study at 21.5 months, even when completely skeletonized. Conversely, in clay it became increasingly difficult to image the pig cadavers over the first year of burial, even when they still retained extensive soft tissue structures.     

Decomposition of buried bodies and methods that may aid in their location

This is the second report on an ongoing study conducted to collect data on the decompositional rates of human cadavers and the first on buried cadavers. Six unembalmed human cadavers were buried separately in unlined trenches of various depths and allowed to naturally decompose for a time period ranging from a month to a year. During the period of burial, data were collected daily on the air, soil, and cadaver temperature at each burial site. At the end of each specified burial period the cadavers were exhumed and examined for the degree of decomposition which had taken place as well as changes in the soil pH, surface vegetation, and carrion insect activity. Analysis of the data shows that the decomposition rate of buried cadavers is highly dependent on the depth of burial and environmental temperatures. The depth at which the cadaver was buried also directly affected the degree of soil and vegetational changes as well as access by carrion insects. Application of this information can contribute to a more accurate estimation of time since death of a buried corpse and may aid in the location of such corpses.     

Time-lapse resistivity surveys over simulated clandestine graves

The aim of this study was to develop a better understanding of how electrical resistivity surveys can be used to locate clandestine graves. Resistivity surveys were conducted regularly over three simulated clandestine graves containing a pig cadaver, no cadaver and a pig cadaver wrapped in tarpaulin, respectively. Additionally, soil and groundwater samples were collected from two more simulated graves outside the survey area. The grave containing a pig cadaver was detectable from a low resistivity anomaly in the survey data. Groundwater data suggest that the resistivity anomaly associated with the surveyed pig grave was caused by a localised increase in groundwater conductivity. Wrapping a cadaver was found to initially change the resistivity response of a grave to a high resistivity anomaly. Resistivity surveys did not detect the disturbed soil in the grave that did not contain a cadaver. Although soil samples showed grave soil to be more porous than undisturbed soil, the lack of response from the grave that did not contain a cadaver suggests that disturbed soil was not responsible for the resistivity anomalies observed in this study. Resistivity surveys successfully detected all graves containing cadavers throughout the study, whilst also showing the potential to eliminate the need for mass excavation in a genuine search.     

The suitability of using domestic pigs (Sus spp.) as human proxies in the geophysical detection of clandestine graves

Research in many forensic science fields commonly uses domestic pigs (Sus spp.) as proxies for human remains, due to their physiological and anatomical similarities, as well as being more readily available. Unfortunately, previous research, especially that which compares the decompositional process, has shown that pigs are not appropriate proxies for humans. To date, there has not been any published research that specifically addresses whether domestic pigs are adequate human proxies for the geophysical detection of clandestine graves. As such, the aim of this paper was to compare the geophysical responses of pig cadavers and human donor graves, in order to determine if pigs can indeed be used as adequate human proxies. To accomplish this, ground penetrating radar (GPR) and electrical resistivity tomography (ERT) responses on single and multiple pig cadaver graves were compared to single and multiple human donor graves, all of which are in known locations within the same geological environment. The results showed that under field conditions, both GPR and ERT were successful at observing human and pig burials, with no obvious differences between the detected geophysical responses. The results also showed that there were no differences in the geophysical responses of those who were clothed and unclothed. The similarity of the responses may reflect that the geophysical techniques can detect graves despite what their contents are. The study implications suggest that experimental studies in other soil and climate conditions can be easily replicated, benefiting law enforcement with missing persons cases.     

Preliminary Observations of Arthropods Associated with Buried Carrion on Oahu

Several studies in Hawaii have focused on arthropod succession and decomposition patterns of surface remains, but the current research presents the first study to focus on shallow burials in this context. Three domestic pig carcasses (Sus scrofa L.) were buried at the depths of 20–40 cm in silty clay loam soil on an exposed ridge on the leeward side of the volcanically formed Koolau Mountain Range. One carcass was exhumed after 3 weeks, another after 6 weeks, and the last carcass was exhumed after 9 weeks. An inventory of arthropod taxa present on the carrion and in the surrounding soil and observations pertaining to decomposition were recorded at each exhumation. The longer the carrion was buried, the greater the diversity of arthropod species that were recovered from the remains. Biomass loss was calculated to be 49% at the 3‐week interval, 56% at the 6‐week interval, and 59% at the 9‐week interval.     

Long‐term Geophysical Monitoring of Simulated Clandestine Graves using Electrical and Ground Penetrating Radar Methods: 4–6 Years After Burial

This ongoing monitoring study provides forensic search teams with systematic geophysical data over simulated clandestine graves for comparison to active cases. Simulated “wrapped,” “naked,” and “control” burials were created. Multiple geophysical surveys were collected over 6 years, here showing data from 4 to 6 years after burial. Electrical resistivity (twin electrode and ERI), multifrequency GPR, grave and background soil water were collected. Resistivity surveys revealed that the naked burial had low‐resistivity anomalies up to year four but then difficult to image, whereas the wrapped burial had consistent large high‐resistivity anomalies. GPR 110‐ to 900‐MHz frequency surveys showed that the wrapped burial could be detected throughout, but the naked burial was either not detectable or poorly resolved. 225‐MHz frequency GPR data were optimal. Soil water analyses showed decreasing (years 4 to 5) to background (year 6) conductivity values. Results suggest both resistivity and GPR surveying if burial style unknown, with winter to spring surveys optimal and increasingly important as time increases.     

Modelling the buried human body environment in upland climes using three contrasting field sites

Despite an increasing literature on the decomposition of human remains, whether buried or exposed, it is important to recognise the role of specific microenvironments which can either trigger or delay the rate of decomposition. Recent casework in Northern England involving buried and partially buried human remains has demonstrated a need for a more detailed understanding of the effect of contrasting site conditions on cadaver decomposition and on the microenvironment created within the grave itself. Pigs (Sus scrofa) were used as body analogues in three inter-related taphonomy experiments to examine differential decomposition of buried human remains. They were buried at three contrasting field sites (pasture, moorland, and deciduous woodland) within a 15 km radius of the University of Bradford, West Yorkshire, UK. Changes to the buried body and the effect of these changes on hair and associated death-scene textile materials were monitored as was the microenvironment of the grave. At recovery, 6, 12 and 24 months post-burial, the extent of soft tissue decomposition was recorded and samples of fat and soil were collected for gas chromatography mass spectrometry (GCMS) analysis. The results of these studies demonstrated that (1) soil conditions at these three burial sites has a marked effect on the condition of the buried body but even within a single site variation can occur; (2) the process of soft tissue decomposition modifies the localised burial microenvironment in terms of microbiological load, pH, moisture and changes in redox status. These observations have widespread application for the investigation of clandestine burial and time since deposition, and in understanding changes within the burial microenvironment that may impact on biomaterials such as hair and other associated death scene materials.     

Geophysical Monitoring of Simulated Clandestine Graves Using Electrical and Ground‐Penetrating Radar Methods: 0–3 Years After Burial*,†

Abstract: This study provides forensic search teams with systematic geophysical monitoring data over simulated clandestine graves for comparison to active cases. Simulated “wrapped” and “naked” burials were created. Multigeophysical surveys were collected over a 3‐year monitoring period. Bulk ground resistivity, electrical resistivity imaging, multifrequency ground‐penetrating radar (GPR), and grave and background “soil‐water” conductivity data were collected. Resistivity surveys revealed the naked burial had consistently low‐resistivity anomalies, whereas the wrapped burial had small, varying high‐resistivity anomalies. GPR 110‐ to 900‐MHz frequency surveys showed the wrapped burial could be detected throughout, with the “naked” burial mostly resolved. Two hundred and twenty‐five megahertz frequency GPR data were optimal. “Soil‐water” analyses showed rapidly increasing (year 1), slowly increasing (year 2), and decreasing (year 3) conductivity values. Results suggest resistivity and GPR surveys should be collected if target “wrapping” is unknown, with winter to spring surveys optimal. Resistivity surveys should be collected in clay‐rich soils.     

Experimental validation of forensic evidence: a study of the decomposition of buried pigs in a heavy clay soil.

In a murder investigation, where the victim had been strangled and buried in a shallow grave, there were discrepancies between the post mortem interval (PMI) as estimated from entomological studies and estimations determined from other evidence. This inconsistency provided the impetus for examining the decay process using pig carcasses as analogues for the human cadaver. The pigs were buried in the immediate vicinity of the original burial site in December 1996, which was the month when the victim was purported to have been interred in the previous year. The buried pigs were then monitored for 5 months which, based on the evidence other than the entomological, was the period over which the corpse was thought to have lain in the ground. The pig corpses were disturbed by scavengers in mid April: this was the same time that the human corpse was discovered in the previous year by scavengers. Insects played no role in the decomposition process until the pig carcasses had been exposed by animals. Blowflies, notably Calliphora vomitoria, were attracted to the exposed tissues and laid eggs from which larvae developed. Calliphora vomitoria is a species often used to estimate PMI. This investigation has shown that soil conditions and low seasonal temperatures had preserved the pig carcasses for longer than might be expected. Using the blowfly larvae to estimate PMI would have produced erroneous results had not the burial environment and exhumation history been investigated.     

Controlled GPR grave research: comparison of reflection profiles between 500 and 250 MHz antennae

Since ground-penetrating radar (GPR) has become a popular search option for clandestine graves, controlled research is essential to determine the numerous variables that affect grave detection. The purpose of this study was to compare GPR reflection profiles of a controlled grave containing a large pig carcass and a blank control grave at 6 months interment in a Spodosol, which is a common soil type in Florida. Data collection was performed in perpendicular orientations over the graves using both 500 and 250 MHz antennae. Since reflection profiles are used to make initial in-field assessments during a forensic search, it is important for controlled research to evaluate this imagery option. Overall, it was possible to detect the grave containing a pig carcass at 6 months interment that was buried in a Spodosol using both the 500 and the 250 MHz antennae. While the 500 MHz antenna provided more detail within the grave containing a pig carcass, including detecting a soil disturbance and the pig carcass, the 250 MHz antenna also provided excellent imagery. Either antenna would provide optimal results for the type of soil that was sampled. Furthermore, it may be possible to locate actual forensic graves in this soil type when no response from the body is noted, as there may be a discernable response from the disturbed soil within the grave shaft and a noticeable disruption of the spodic horizon. Finally, survey orientation may also affect detection. Since data collection performed in two perpendicular directions detected the pig carcass and the grave floor of the control grave, data collection for an actual search involving a body interred for a long postmortem interval should be performed in both directions when time permits.     

Ground penetrating radar surveys to locate 1918 Spanish flu victims in permafrost

The "Spanish Flu" killed over 40 million people worldwide in 1918. Archival records helped us identify seven men who died of influenza in 1918 and were interred in Longyearbyen, Svalbard, Norway, 1,300 km from the North Pole. Ground Penetrating Radar (GPR) was used successfully, in a high-resolution field survey mode, to locate a large excavation with seven coffins, near the existing seven grave markers. The GPR indicated that the ground was disturbed to 2 m depth and was frozen below 1 m. Subsequent excavation showed that: a) the GPR located the position of the graves accurately, b) the coffins were buried less than 1 m deep, and c) that the frozen ground was 1.2 m deep where the coffins were located. The GPR assisted in planning the exhumation, safely and economically, under the high degree of containment required. Virologic and bacteriologic investigations on recovered tissues may give us an opportunity to isolate and identify the micro-organisms involved in the 1918 influenza and expand our knowledge on the pathogenesis of influenza.     

Application of forward‐looking infrared (FLIR) imaging from an unmanned aerial platform in the search for decomposing remains

Traditional methods of cadaver detection in outdoor environments include manual ground search, cadaver dogs, and manned aerial reconnaissance during daylight. These methods have limitations; however, a potential low‐cost alternative may be to employ thermal imaging equipment mounted on an unmanned aerial vehicle (UAV) to detect heat emitted by insect and bacterial activity on the decomposing remains. No studies have addressed the influence of wrappings on detection of maggot mass thermal signatures nor assessed thermal detection of smaller body fragments. We addressed these knowledge gaps by utilizing a two‐phase experimental approach to explore thermal detection of carcasses using UAV‐mounted infrared imaging. In Phase 1, pig body fragments were deposited on the surface or shallow buried. In Phase 2, whole pig carcasses were deposited in four conditions: on the surface uncovered, wrapped in plastic or carpet, or buried. Our results demonstrated that observable heat emissions from remains corresponded to peak insect activity during active decay and could be readily detected in uncovered whole carcasses and fragments. Although plastic and carpet wrappings partly impeded detection of insect heat signatures, these materials were clearly detectable themselves because of their contrast to the background ground surface. Thermal signatures of buried partial remains and disturbed gravesoil were also observed; however, the buried whole carcass transitioned to adipocere prior to the decay stage and without any insect colonization or heat signature. These data can inform operational implementation of this technique to complement existing search strategies to offer a robust, low‐cost alternative for use where scene characteristics allow.     

Cadaver dog and handler team capabilities in the recovery of buried human remains in the southeastern United States

The detection of human remains that have been deliberately buried to escape detection is a problem for law enforcement. Sometimes the cadaver dog and handler teams are successful, while other times law enforcement and cadaver dog teams are frustrated in their search. Five field trials tested the ability of four cadaver dog and handler teams to detect buried human remains. Human and animal remains were buried in various forested areas during the summer months near Tuscaloosa, Alabama. The remains ranged in decomposition from fresh to skeletonized. Cadaver dogs detected with varying success: buried human remains at different stages of decomposition, buried human remains at different depths, and buried decomposed human and animal remains. The results from these trials showed that some cadaver dogs were able to locate skeletonized remains buried at a significant depth. Fresh and skeletonized remains were found equally by the cadaver dogs along with some caveats. Dog handlers affected the reliability of the cadaver dog results. Observations and videotape of the cadaver dogs during field trials showed that they were reliable in finding buried human remains.     

Vegetation dynamics as a tool for detecting clandestine graves

The burial of a body can affect plant communities through mechanical disturbance and nutrient balance alteration. We performed an experimental trial using five swine carcasses buried in an open site in Italy. Vegetation dynamics was monitored recording monthly every plant individual on a regular sampling grid during 1 year on the graves, on an empty control grave, and on an undisturbed plot. Plant species composition and cover were significantly different between the disturbed and the undisturbed plots. Disturbed plots showed the increase in ruderal species and the reduction in stress-tolerant ones. Graves and the control grave could not be distinguished from each other. Disturbance was the main factor affecting plant cover, while the presence of a buried body did not affect vegetation dynamics. However, disturbance could be easily detected; the functional approach seems promising for the identification of dynamic patterns to be used in different biogeographic and ecological contexts.     

Reconstructing the Sequence of Events Surrounding Body Disposition Based on Color Staining of Bone*

Abstract: Literature regarding bone color is limited to determining location of primary and secondary dispositions. This research is the first to use bone color to interpret the sequence of events surrounding body disposition. Two scenarios were compared—bones buried and then exposed on the ground surface and bones exposed then buried. Forty juvenile pig humeri with minimal tissue were used in each scenario with an additional 20 controls to determine if decomposing tissue affects bone color. Munsell Color Charts were used to record bone color of surface and 2.5 cm cross‐sections. Results reveal five main surface colors attributed to soil, sun, hemolysis, decomposition, and fungi. Fungi on buried bones suggests prior surface exposure. Cross‐sections of strictly buried bones are identical to buried then exposed bone, stressing the importance of bone surface analysis. Cross‐sectioning may help verify remains have been exposed then buried. Decomposition of excess tissue creates minimal color staining.     

Soilwater Conductivity Analysis to Date and Locate Clandestine Graves of Homicide Victims

In homicide investigations, it is critically important that postmortem interval and postburial interval (PBI) of buried victims are determined accurately. However, clandestine graves can be difficult to locate; and the detection rates for a variety of search methods (ranging from simple ground probing through to remote imaging and near‐surface geophysics) can be very low. In this study, simulated graves of homicide victims were emplaced in three sites with contrasting soil types, bedrock, and depositional environments. The long‐term monthly in situ monitoring of grave soil water revealed rapid increases in conductivity up to 2 years after burial, with the longest study evidencing declining values to background levels after 4.25 years. Results were corrected for site temperatures and rainfall to produce generic models of fluid conductivity as a function of time. The research suggests soilwater conductivity can give reliable PBI estimates for clandestine burials and therefore be used as a grave detection method.     

Identification of a Buried Cadaver Based on Finger Ridge Characteristics of a Hand Protected by a Latex Glove

This paper presents the case of a cadaver buried in a pine grove, in loamy soil at a depth of about 1.8 m. The case is quite interesting due to the fact that one hand of the victim was bare and the other one was clad in a latex glove. In the laboratory, the severed hands were gently washed with water. The left palm exhibited signs of advanced decomposition. The ridges were visible only on the thumb. The gloved hand was found to be in much better condition. There were signs of saponification on the palm. Ridges on both the palm and all fingers were visible. The fingers of the right hand, palm prints, and the thumb of the left hand were successfully matched against a ten-print card. The match provided the police with a positive identification of the missing person.     

Effects of hydrated lime and quicklime on the decay of buried human remains using pig cadavers as human body analogues

Recent casework in Belgium involving the search for human remains buried with lime, demonstrated the need for more detailed understanding of the effect of different types of lime on cadaver decomposition and its micro-environment. Six pigs (Sus scrofa) were used as body analogues in field experiments. They were buried without lime, with hydrated lime (Ca(OH)(2)) and with quicklime (CaO) in shallow graves in sandy loam soil in Belgium and recovered after 6 months of burial. Observations from these field recoveries informed additional laboratory experiments that were undertaken at the University of Bradford, UK. The combined results of these studies demonstrate that despite conflicting evidence in the literature, hydrated lime and quicklime both delay the decay of the carcass during the first 6 months. This study has implications for the investigation of clandestine burials and for a better understanding of archaeological plaster burials. Knowledge of the effects of lime on decomposition processes also has bearing on practices involving burial of animal carcasses and potentially the management of mass graves and mass disasters by humanitarian organisations and DVI teams.     

Collembola of the grave: a cold case history involving arthropods 28 years after death

This report describes a cold case in which a cadaver of a 28-year-old female was exhumed in February 2005 from a cemetery in Battle Creek, Michigan. She had sustained a gunshot wound to the head and was found dead in her home on November 15, 1977. The body of the victim was subsequently embalmed and then buried at a depth of 1.8 m in an unsealed casket that was placed inside an unsealed cement vault. The exhumation yielded thousands of live specimens of a single species of the order Collembola or spring tails, Sinella (Coecobrya) tenebricosa (Entomobryidae). This species is considered to be a "tramp" species, cosmopolitan in the United States and Canada. Due to the ideal environmental conditions at the site, the population of this species underwent growth and development inside the casket for a number of years. Collected with the Collembola were large numbers of Acarina (mites) of the Family Glycyphagidae, and fly puparia, Conicera tibialis Schmitz (Order: Diptera, Family: Phoridae), also known as coffin flies. These invertebrates are sometimes mentioned by forensic investigators as occurring on corpses in graves, but aspects of their life history are rarely described. The species of Collembola that was found surviving and reproducing on this corpse in a casket exhumed after 28 years was the oldest reported grave site occurrence for any collembolan species based on a survey of the literature back to 1898.     

Taphonomic Effects of Mechanical Plowing on Buried Juvenile‐Sized Remains

Agricultural activity is a worldwide taphonomic process and can present unique challenges in the recovery of buried remains. Previous research has been mostly within the realm of site formation processes of archeological sites utilizing only surface material. This research expands upon the previous research by incorporating the distribution of subsurface material by the use of archeological excavation techniques. An experiment was conducted utilizing juvenile pig (Sus scrofa) skeletons buried in relative anatomical position at two different depths (15 cm below the surface [cmbs] and 22 cmbs). The burials were then subjected to different intervals of mechanical plowing: one, three, five, seven, or 10 plow passes. The skeletal material was recovered using pedestrian survey followed by hand excavation and screening of all sediments. This research shows that there is a significant relationship between the degree of plowing and the distance skeletal material is distributed and the percentage of material recovered undamaged.