INTRODUCTION

Forensic anthropology researchers conduct their analysis on recently deceased individuals (typically within the last 50 years) and within the context of the law—in other words, as part of a criminal investigation. This means that forensic anthropologists can assist law enforcement agencies in several different ways, including aiding in the identification of human remains whether they are complete, fragmentary, burned, scattered, or decomposed. Additionally, forensic anthropologists can help determine what happened to the deceased at or around the time of death as well as what processes acted on the body after death (for example, whether the remains were scattered by animals, whether they were buried in the ground, or whether they remained on the surface as the soft tissue decomposed).¹

Many times, because of their expertise in identifying human skeletal remains, forensic anthropologists are called to help with outdoor search-and-recovery efforts, such as locating remains scattered across the surface or carefully excavating and documenting buried remains. In other cases, forensic anthropologists recover remains after natural disasters or accidents, such as fire scenes, and can help identify whether each bone belongs to a human or an animal. Forensic anthropology spans a wide scope of contexts involving the law, including incidences of mass disasters, genocide, and war crimes.¹

Preparation Phase

Before a search can be carried out Forensic Scientists and Investigators must complete a preparation phase.

During this phase the type of search should be identified. At this stage, the forensic scientists should be provided with or request the case background and intelligence. This may include interview notes, statements, surveillance material, exhibits and photographs of the crime scene or search area.³

Desk Review

A desk study allows all materially relevant data, information, and case intelligence to be collated and analyzed. As a minimum this should include the analysis of maps, reports and publications that are typically available for any federal or national geological survey. The acquisition of high-resolution air photos, Google Earth imagery, LiDAR, hyperspectral or thermal imagery or satellite imagery may reveal subtle ground disturbances potentially associated with a burial and enable the geology to be evaluated. Air reconnaissance observations from a police/military/search and rescue helicopter is of particular value for open areas searches so that the context and outer limits of the search area can be determined, and topographic ground disturbances observed.³

Now that the search area has been defined and the search plan identified the search can now begin. There are numerous methods that can be used to locate human remain/ crime scene, however they fall into two categories: Non-invasive and Invasive. Non-Invasive searches do not have any potential of damaging evidence or osteological material as they do not penetrate the ground surface. Invasive searches do have the potential of damaging evidence or osteological material as they do penetrate the ground surface. This is why when using invasive methods care must be taken to reduce the potential harm these methods might cause.

Non-Invasive Search Techniques

Aerial Reconnaissance

As the name suggests, aerial reconnaissance methods find and record disposition sites from above. Aerial photography was first used in archaeology in the early twentieth century and its use expanded significantly after World War I. Archaeologists and their pilots would fly over areas they were interested in investigating, looking for signs of archaeological sites and land formations in which sites or artifacts are commonly found and then photographing them from the air.²

As technologies have changed and developed, new avenues of aerial reconnaissance have opened up. One such technology is Light Detection and Ranging, known as LiDAR, which involves lasers scanning landscapes and sites from an aircraft to create digital elevation models. This technology “sees through” dense vegetation and ground cover. The availability of drones with photographic equipment attached has dramatically increased the accessibility and affordability of aerial reconnaissance efforts. Anthropologists who once needed to hire a pilot can conduct many aerial reconnaissance flights themselves.²

With the advent of Google Earth, initial reconnaissance flights might not be needed since Google’s satellite imagery is freely available and can often provide necessary aerial images. Since this tool is right at a person’s fingertips, it can be used as a first pass of preliminary reconnaissance, guiding future, more-detailed inquiries with techniques that offer greater resolution. Google Earth also provides historical data through satellite imagery archived over time, allowing anthropologists to compare views of a location, potentially revealing changes in environmental conditions, water levels, and even a site’s condition (before plowing, construction, or some other disturbance). Since Google Earth is free and drone technology is increasingly affordable, barriers to conducting reconnaissance have decreased, which is good for forensic anthropologists.²

Ground Search

Eventually, of course, forensic anthropologists must get out of airplanes and their offices and check out potential sites in person to see what is actually there. They conduct ground reconnaissance to find and record disposition sites. This type of reconnaissance does not involve excavation. It examines what is visible and accessible directly on the surface of the ground.²

The search strategy must consider for example: the search type, outer boundary of the search areas, likelihood that the target can be located, properties and condition of the target, objectives and extent of the search, required resources, choice of search assets, press management, family members (if the search is for a suspected homicide grave), cost, time frames, relevance, geology and ground conditions. It is recommended that ground searches are carried out from the macro to the micro-scale and from the non-invasive to the invasive. This approach permits the effective management of the crime scene to avoid the possibility of cross-contamination.³

Ground searches may take place in a range of settings, from the confines of a small garden defined by boundary fences, walls or hedges to Episodes Vol. 40, no. 2 107 vast expanse of a land such as: a cost lines, deserts or mountainous environment. Each geographical settings is unique and requires a specific search approach in terms of the strategy deployed. A ground search can also be influenced by the time, costs, available resources and time or media pressures. Some ground searches may be completed following just a couple of hours searching. Alternatively, they could take days to weeks or in some situations many years. Some searches never become resolved even though the intelligence strongly provides a search area.³

Reconnaissance

Reconnaissance walk-over surveys provide the opportunity for the ground diggability to be evaluated and the search area limits to be defined. Sometime a “quick win” is possible, where evidence for a burial is found during the initial visit. This may be the exposure of human remains by weathering and erosion or the recognition of topographic features associated with digging a grave or hide. Typically, this may include: (a) settlement of the backfilled material above the target, (b) color changes caused by lower soil layers being placed on the ground surface, (c) the occurrence of excessive material caused by the bulking of the displaced soil and the additional volume taken up by the target, (d) enhanced or reduced vegetation, (e) changes in vegetation and (d) animal scavenging of increased insect activity due to decomposition.³

Lanes and Sectors

Search lanes and search sectors may be linear, square, rectangular or irregular (Figs. 3 and 4). They should be defined by high visibility string, ‘police’ or ‘crime scene’ tape. These enable to search teams to focus on a manageable and proportionate search areas. Search lanes permit the accurate recording of any items found.³

The search boundary, lanes and sectors and any evidential items found must be accurately recorded using a minimum of field portable global positioning system (GPS) technology. This should include information on what, when, where and how each item was found, and the names of the search team member who located and recovered the items. This information may later be required in a court of law. Therefore, the recording of the search must be consistent with the requirements of the relevant authority or criminal justice system. The method of recording a search will vary include: written notes and logs, field diagrams, digital photographs, video, compass-clinometer, tape, field portable and hand held GPS, highly sophisticated total base station GPS or 3D laser scanning and the use of a drone or UAVs.³

Victim Recovery Dogs

Victim Recovery Dogs (VRD’s) (also known as victim detector dogs, cadaver dogs, body dogs and sniffer dogs) can be trained to detect buried human remains, currency, explosives, firearms or drugs. The dogs obey the ‘Scent-Pathway-Receptor’ (CPR) model by detecting VOC’s (known also as scent or odor). The training, handling and deployment of detector dogs is a highly specialized skill. Interestingly, the success of a detector dog seems to be only partially understood. It is suspected that ability of a search dogs may be influenced geological and environmental factors, including for example groundwater flows and leachate plumes, soil permeability, wind direction and speed and barometric pressure fluctuations. The ground investigation of positive detector dog responses may, or may not, result in the recovery of human remains. Where human remains are not evident in the immediate vicinity there is a tendency is to classify the VRD response as incorrect and a search may be halted as a consequence. However, this may occur when the VRD responses are wrongly interpreted by investigators. In cases where the search area has been extended beyond the VRD response site victim’s remains have subsequently been recovered in a near-by grave. This may possibly be explained by an understanding of the geology and groundwater flows.³

When a possible body is identified, the surveyor places a flag in the ground to identify its location and continues surveying. No excavation occurs at this time. Once the survey is complete, the flagged locations are precisely identified by GPS coordinates. Their locations are recorded, and evidence can then be collected.²

Geophysical

Forensic Anthropologists also have subsurface detection tools that allow them to conduct reconnaissance below the surface of the ground without excavating. Important nondestructive tools are geophysical sensing devices such as Ground Penetrating Radar (GPR). These devices actively probe underground by passing various types of energy, laser, or radio waves through the soil and measuring how the waves are reflected back to find out what is below the surface. Passive geophysical sensing devices measure physical properties of the soil, such as gravity and magnetism. These tools capture data that generate a map of what lies below the surface.²

These instruments can be deployed from the air or ground based, over land or in water. Common methods used in ground searches include ground penetrating radar (GPR), resistivity, magnetometer, and electromagnetic surveys. It should be noted that geophysics alone will not give a guarantee for the presence of absence of a buried target. Two or three complementary methods are recommended to be deployed consecutively and in a phased manner as part of a planned search strategy.³

These highly technical nondestructive subsurface methods require a trained practitioner capable of running the machines over the site and interpreting the resulting data.²

Invasive Search Techniques

Auger

As a last resort, anthropologists can use probes that physically dig below the surface to learn more about what lies underground but risk damaging the site. A probe involves using a rod or auger, which looks like a giant drill bit, inserted into the ground to drill down as far as possible into the soil. The auger is then brought back to the surface, carrying with it samples of soil from various levels below the surface. It is easy to see why this method must be used sparingly and with caution as it involves plunging a sharp, destructive device into the ground, potentially damaging anything it encounters, including human burials.²

Auguring is most effective when used by a line of search trained geologists or police officers at no less than approximately 0.2 m spacing, or as otherwise may be considered appropriate. Auguring and the use probes can cause the emission of gases or volatile organic compounds from impermeable soils, which can enhance the possibility of detection by a trained detector.³

Test Pits

Another method of physically examining the subsurface is making shovel test pits, which are essentially very small excavations, usually one meter by one meter in size (it varies), to see if there is a potential burial site under the surface. Typically, several test pits are opened at the same time at a consistent distance from one another. This method is particularly useful for confirming the results of other forms of reconnaissance.²

INITIAL SKELETAL ANALYSIS

While bioarchaeology and forensic anthropology have different goals and purposes, they both rely on skeletal analysis to reveal information about the deceased. Whether they aim to determine more information regarding an individual deceased for thousands of years (bioarchaeologists) or one who died within the last year (forensic anthropologists), they carry out the same basic steps as part of their analysis.

Is It Bone?

One of the most important steps in any skeletal analysis starts with determining whether or not material suspected to be bone is in fact bone. Though it goes without saying that a forensic anthropologist or bioarcheologist would only carry out analysis on bone, this step is not always straightforward. Whole bones are relatively easy to identify, determining whether or not something is bone becomes more challenging once it becomes fragmentary. For example, at high heat such as that seen on fire scenes, bone can break into pieces. During a house fire with fatalities, firefighters watered down the burning home. After the fire was extinguished, the sheetrock (used to construct the walls of the home) was drenched and crumbled. The crumbled sheetrock was similar in color and form to burned, fragmented bone, therefore mistakable for human remains (Figure 3.1). Forensic anthropologists on scene were able to separate the bones from the construction material, helping to confirm the presence of bone and hence the presence of individual victims of the fire. In this case, forensic anthropologists were able to recognize the anatomical and layered structure of bone and were able to distinguish it from the uniform and unlayered structure of sheetrock.¹

As demonstrated by the example above, both the macrostructure (visible with the naked eye) and microstructure (visible with a microscope) of bone are helpful in bone identification. Bones are organs in the body made up of connective tissue. The connective tissue is hardened by a mineral deposition, which is why bone is rigid in comparison to other connective tissues such as cartilage. In a living body, the mineralized tissue does not make up the only component of bone—there is also blood, bone marrow, cartilage, and other types of tissues. However, in dry bone, two distinct layers of the bone are the most helpful for identification. The outer layer is made up of densely arranged osseous (bone) tissue called compact (cortical) bone. The inner layer is comprised of much more loosely organized, porous bone tissue whose appearance resembles that of a sponge, hence the name spongy (trabecular) bone. Knowing that most bone contains both layers helps with the macroscopic identification of bone (Figures 3.2, 3.3). For example, a piece of coconut shell might look a lot like a fragment of a human skull bone. However, closer inspection will demonstrate that coconut shell only has one very dense layer, while bone has both the compact and spongy layers.¹

Cranial anatomy is slightly different as compared to that of a long bone in cross-section. The compact (cortical) bone layers sandwich the spongy (trabecular) bone. One layer of compact bone forms the very outer surface of the skull and the other lines the internal surface of the skull.¹

The microscopic identification of bone relies on knowledge of osteons, or bone cells (Figure 3.4). Under magnification, bone cells are visible in the outer, compact layer of bone. The bone cells are arranged in a concentric pattern around blood vessels for blood supply. The specific shape of the cells can help differentiate, for example, a small piece of PVC (white plastic) pipe from a human bone fragment (Figure 3.5).¹

Is It Human?

Once it can be determined that an object is bone, the next logical step is to identify whether the bone belongs to a human or an animal. Bioarcheologists must make this determination each time they come across remains at an archaeological site. Forensic anthropologists are faced with this question in everyday practice because human versus nonhuman bone identification is one of the most frequent requests they receive from law enforcement agencies.¹

There are many different ways to distinguish human versus nonhuman bone. The morphology (the shape/form) of human bone is a good place for students to start. Identifying the 206 bones in the adult human skeleton and each bone’s distinguishing features (muscle attachment sites, openings and grooves for nerves and blood vessels, etc.) is fundamental to skeletal analysis.¹

Nevertheless, there are many animal bones and human bones that look similar. For example, the declawed skeleton of a bear paw looks a lot like a human hand, pig molars appear similar to human molars, and some smaller animal bones might be mistaken for those of an infant. To add to the confusion, fragmentary bone may be even more difficult to identify as human or nonhuman. However, several major differences between human and nonhuman vertebrate bone help distinguish the two.¹

Bioarcheologists and forensic anthropologists pay special attention to the density of the outer, compact layer of bone in both the cranium and in the long bones. Human cranial bone has three distinctive layers. The spongy bone is sandwiched between the outer (ectocranial) and inner (endocranial) compact layers. In most other mammals, the distinction between the spongy and compact layers is not always so definite. Secondly, the compact layer in nonhuman mammal long bones can be much thicker than observed in human bone. Due to the increased density of the compact layer, nonhuman bone tends to be heavier than human bone (Figure 3.6).¹

The size of a bone helps determine whether it belongs to a human. Adult human bones are larger than subadult or infant bones. However, another major difference between human adult bones and those of a young individual or infant human can be attributed to development and growth of the epiphyses (ends of the bone). The epiphyses of human subadult bones are not fused to the shaft (Figure 3.7). Therefore, if a bone is small and it is suspected to belong to a human subadult or infant, the epiphyses would not be fused. Many small animal bones appear very similar in form compared to adult human bone, but they are much too small to belong to an adult human. Yet they can be eliminated as subadult or infant bones if the epiphyses are fused to the shaft.¹

Is It Modern or Archaeological?

As discussed earlier, bioarcheologists are concerned with human remains from archaeological contexts, while forensic anthropologists work with modern cases that fall within the scope of law enforcement investigations. Accordingly, it is important to determine whether discovered human remains are archaeological or forensic in nature.¹

In many instances, bioarcheologists work at known archaeological sites. Nevertheless, every bioarcheologist and forensic anthropologist should begin their analysis by reviewing the context in which the remains were discovered. This will help them understand a great deal about the remains, including determining whether they are bioarcheological or forensic in nature as well as considering legal and ethical issues associated with the collection, analysis, and storage of human remains.¹

The “context” refers to the relationship the remains have to the immediate area in which they were found. The context includes the specific place where the remains were found, the soil or other organic matter immediately surrounding the remains, and any other objects or artifacts in close proximity to the body. For example, imagine that a set of remains has been located during a house renovation. The remains are discovered below the foundation. Do the remains belong to a murder victim? Or was the house built on top of an ancient burial ground? Observing information from the surroundings can help determine whether the remains are archaeological or modern. How long ago was the foundation of the house erected? Are there artifacts in close proximity to the body, such as clothing or stone tools? These are questions about the surroundings that will help determine the relative age of the remains.¹

Clues directly from the skeleton may also indicate whether the remains are archaeological or modern. For example, tooth fillings can suggest that the individual was alive recently (Figure 3.8). In fact, filling material has changed over the decades, and the specific type of material used to fix a cavity can be matched with specific time periods. Gold was used in dental work in the past, but more recently composite (a mixture of plastic and fine glass) fillings have become more common.¹

References:

1. Ashley Kendell, Alex Perrone, and Colleen Milligan, “Bioarcheology and Forensic Anthropology” In Explorations, ed. Beth Shook, Katie Nelson, Kelsie Aguilera and Lara Braff (Arlington: American Anthropological Association, 2019). https://pressbooksdev.oer.hawaii.edu/explorationsbioanth/chapter/osteology/

2. Amanda Wolcott Paskey and AnnMarie Beasley Cisneros, Digging into Archaeology: A Brief OER Introduction to Archaeology with Activities (California: Academic Senate for California Community College, 2020). https://asccc-oeri.org/wp-content/uploads/2020/06/OERI-Archaeology_Final_4_29.pdf

3. Laurance J. Donnelly and Mark Harrison, “ Ground searches for graves and buried targets related to homicide, terrorism and organised crime,” Journal of International Geoscience 40 (2017). https://www.episodes.org/journal/view.html?volume=40&number=2&spage=106&vmd=A

Figure Attributions:

Figure 3.1 Example of burned sheetrock by Alex Perrone original to Explorations: An Open Invitation to Biological Anthropology is under a CC BY-NC 4.0 License.

Figure 3.2 Cross section of human long bone original to Explorations: An Open Invitation to Biological Anthropology by Mary Nelson is under a CC BY-NC 4.0 License.

Figure 3.3 Anatomy of a Flat Bone (Anatomy & Physiology,) Figure 6.3.3 by OpenStax is used under a CC BY 4.0 License.

Figure 3.4 Bone (248 12) Bone cross section by Doc. RNDr. Josef Reischig, CSc. is used under a CC BY-SA 3.0 License.

Figure 3.5 Example of PVC pipe by Alex Perrone original to Explorations: An Open Invitation to Biological Anthropology is under a CC BY-NC 4.0 License.

Figure 3.6 Animal bone cross-section by Alex Perrone original to Explorations: An Open Invitation to Biological Anthropology is under a CC BY-NC 4.0 License.

Figure 3.7 Tib fib growth plates by Gilo1969 at English Wikipedia is used under a CC BY 3.0 License.

Figure 3.8 Filling by Kauzio has been designated to the public domain (CC0).