Excavation and Retrieval of Forensic Remains


The need for an archaeological assessment of a location where human remainsare expected to be found arises frequently. Mass murders in various countries such as Bosnia may also require archaeological expertise. Sometimes a particular grave in a cemetery may have to be excavated, in order to observe whether it is disturbed and if the remains belong to the person who was reportedly buried there. Forensic archaeology entails the application of standard archaeological techniques, modified to meet the needs of crime scene processing where skeletons or buried bodies are present.
In the past it has often happened that burials were excavated by large ground-moving equipment and shovels. Surface remains were collected without paying attention to the distribution of the remains and other taphonomic factors. It is clear, however, that much information is lost in this way. Scientific excavation and retrieval require some basic training, and police department sare slowly incorporating archaeology courses in their training schedules. Retrieval, excavation, analysis and personal identification of decomposed remains and their associated artifacts require a multidisciplinary approach involving additional experts such as pathologists, botanists and entomologists. The purpose of this article is to describe forensic archaeological principles. The discussion covers scientific excavation techniques, discovery, recovery and processing of human remains and artifacts, as well as advising the police about the circumstances in which the remains are buried.

Principles of Archaeology

Two basic principles of archaeology are stratigraphy and superposition. Stratigraphy refers to the formation of strata or layers. It is the sum total of the processes whereby the layers are accumulated. Superposition implies that the oldest evidence is deposited first, and located at the deepest layer. The formation of stratigraphy can be described as the opposite of the natural process of erosion, but erosion can play a role after the various matrices have been laid down. Water and wind erosion, as well as plant, human and animal activity can alter the deposits. It is impossible to dig a grave, and then cover it up in such a way that the exact, original stratigraphy is retained. Superposition gives an indication of the relative order in which objects were placed in a grave, thus, the objects placed in a grave last are discovered first.

Location of Skeletal Remains

One of the most difficult aspects in forensic archaeology is to find the buried body. Graves are often found by accident or as a result of construction work. An eye witness or informant can also lead the police to a site where there may be human remains (buried or on the surface). Surface indicators are often destroyed in older burials, and it is not always possible to determine whether the grave is of forensic or archaeological nature. Situations may also arise where relatives of a deceased person may claim that the burial was carelessly disturbed and the remains scattered by the cemetery authority during construction or relocation. They may request that the grave is opened to see if it is disturbed and whether all parts of the body are still there.
There are several techniques to locate buried bodies ranging from simple observation to the use of sophisticated equipment. In general, surface changes in soil and vegetation may indicate a grave. These include the following.
1. Soil compactiomalthough the infill of the grave would probably have been leveled with the surface at the time of burial, the soil will compact after some time to form a concave area, or double depression, known as the primary and secondary depressions. These depressions are not only formed because of the compaction of the infill but also as a result of the decomposition of the buried body. The largest volume to collapse during decomposition is the thorax (secondary depression). This secondary depression occurs in the upper third of the grave’s surface, and is usually deeper than the total concave area which denotes the approximate outline of the grave pit (Fig. 1). The depth varies according to the type of soil, the depth of the grave, and the amount of water present. This depression is the most obvious in the first months after the burial.
2. Disturbed vegetationthis includes the plants on the surface of the grave itself and surrounding areas where the excavated soil (upcast) was thrown when the remains were interred (Fig. 1). Usually the area directly above the grave may be void of plants for some time, although a shallow grave, with no wrapping around the body, may stimulate growth due to the nutrients originating from the decaying body (Fig. 2). The presence of pioneer plants, e.g. weeds, occurring in a localized area may also be indicative of a fresh grave. Weeds are usually the first plants to appear because they are fast growers, and they can often be distinguished from the surrounding vegetation.
3. Disturbed soihusually the soil from the surface and that originating from the grave pit mixes, which leads to obvious differences in color and texture with the surrounding matrix.
Indications of the presence of a grave, a, Undisturbed stratigraphy; b, undisturbed plant roots; c, disturbed plant roots; d, original undisturbed vegetation; e, upcast remaining on the surface; f, g, different vegetation in the area trampled and disturbed during the original excavation of the grave; h, new plant growth,
Figure 1 Indications of the presence of a grave, a, Undisturbed stratigraphy; b, undisturbed plant roots; c, disturbed plant roots; d, original undisturbed vegetation; e, upcast remaining on the surface; f, g, different vegetation in the area trampled and disturbed during the original excavation of the grave; h, new plant growth,
Plant growth in the vicinity of the remains. a, Original vegetation; b, c, different vegetation in the area trampled and disturbed during the original excavation of the grave; d, area of new growth on the grave surface; e, area of lush new growth on the grave surface due to the availability of nutrients from the decomposing body.
Figure 2 Plant growth in the vicinity of the remains. a, Original vegetation; b, c, different vegetation in the area trampled and disturbed during the original excavation of the grave; d, area of new growth on the grave surface; e, area of lush new growth on the grave surface due to the availability of nutrients from the decomposing body.
These factors are, of course, influenced by the environment. Unless the event occurs soon after harvesting in a farmland these changes may be difficult to observe because of regular plowing. The same is true of sandy soil, where the sides of the grave may collapse and obscure the depression of the grave’s surface.
Specially trained cadaver dogs may be used to locate buried remains. They smell the gas formed by the process of decay, and would therefore be most effective shortly after death. A metal detector is very useful to start the surface examination. The ground may also be probed to locate areas of different compaction. Several methods for remote sensing of graves exist, such as ground-penetrating radar, infrared and aerial photography, electromagnetic radiation and the use of microwaves.


The basic toolkit of any (forensic) archaeologist includes equipment for setting up the grid, excavation (to locate and unearth the remains) and once found, removal with finer tools. A suggested list is shown in Table 1. This list may be expanded, where possible, to include a GPS (global positioning system) instrument to ascertain the locality of the grave and a metal detector. For cases where advanced decomposition has taken place but much soft tissue is present, a body bag may be needed both to reduce the offensive odor and to avoid any infectious disease agent dispersement and to retain/preserve evidence (e.g. bullets).

Recovery of the Remains

All evidence must remain in situ until documented. A clear, concise, meaningful, written description of the pertinent aspects of the crime scene is the most important method of documentation. The recovery should be done in such a fashion that the integrity of the evidence is maintained in order for the information to be acceptable in a judicial or criminal investigation procedure. Context is provided via documentation, and contamination must be avoided. All evidence recovered should be labeled at the scene, so that no questions occur as to actual possession during the procedure of marking and storing the evidence. Forms detailing the processing of the evidence must be signed by both the archaeologist and police during the chain of custody.

Recovery of a buried body

The recovery of a buried body requires a preplanned methodical approach. Although the methodology to be employed is archaeological, the recovery should be processed as a crime scene. The first priority is to avoid contamination of the scene and disturbing any evidence. The area must therefore be secured, preferably by taping off the total area. A suitable access route must be established, and all people not directly involved with the recovery must not be allowed on the scene. All movement should be on the established route, which should not disturb any evidence. Record the access route in the notes on the scene and indicate it on the plan. Security is needed overnight if necessary.
Prior to excavation the scene should be photographed from various directions. Detailed notes must be taken on all the aspects of the scene such as the vegetation, climate, topography, geology, amount of sunshine, and any other observations. Flying insects should be caught at this stage, and all other insects collected and recorded where they occur in the excavation.
The surface should be cleared of vegetation without disturbing any of the evidence, after botanical samples have been taken. A three-dimensional grid system can be established with a fixed elevated datum point. If possible the grid should be oriented in north-

Table 1 Basic archaeological tools used in surface and burial site excavation.

Setting up the grid
Two tape measures (for shorter and longer distances) Line level
Metal stakes or nails (to set up the grid)
String (to define the boundary of each trench as well as grid lines). A different color string can be used for the baseline Compass (to determine the orientation of the buried body and grid). A prismatic compass can also be used for surveying, although more accurate equipment such as a theodolite, aladate or ‘dumpy’ level should be used if available Pruning shears or lopper and a saw (to remove tree roots and branches)
Searching for and excavating the remains
Spades and pickaxes (for a deep grave) Trowels (to remove soil)
Dental picks or bamboo skewers (for finer work around bones) Paint brushes, big and small (to gently remove soil around bones and artifacts) One or two buckets (to collect and carry the excavated soil to be screened) Screens, with 1.5 mm and 5 mm mesh (to screen the soil from the burial)


Indelible pens (to write tag names, bags or boxes)

Notebook, felt tip and ballpoint pens, pencils, erasers, ruler, graph paper, scissors Two cameras for black-and-white and color slide photography and film Scale, indicating at least 50 cm with centimetric divisions for detail photographs Arrow which may be part of the scale (to point to magnetic north on photographs)
Molding agent such as plaster of Paris, silicone or dental algenate (for molding possible footprints and tool marks). Suitable containers and a spoon or spatula for mixing the molding agent Releasing agent, such as ski wax (for use during molding)
Handling and packaging of remains and evidence
Containers and plastic bags, big and small, for insects, bones, teeth and physical evidence recovered Packaging material, such as bubble plastic, bags, screw top bottles and boxes Tape to seal containers Labels
Rubber gloves and protective clothing if soft tissue is present
south direction to make reconstruction easier. A scale plan of the site should be drawn and all evidence recorded with reference to the grid.
If any footprints, tire tracks or drag marks are visible on the surface, they should be described, measured, photographed and cast. A ‘dam’ must be built around the evidence to keep the casting agent in place. A releasing agent such as ski wax must be applied before the casting agent is poured. The pouring should be gentle and even over the entire surface of the evidence. Make sure that the cast is strong enough to be removed without breaking after it has set. The cast can be reinforced by placing thin wire or bamboo skewers crosswise on the surface of the wet casting agent. Sometimes prints are found in a soft matrix that will not support casting in this manner. Here the print can be sprayed with a mist of cellulose acetate dissolved in acetone. As the mist settles on the surface, the acetone evaporates leaving a fine molded skin of acetate. Suitable commercial silicones can also be used for this purpose. This skin mold can then be used as the basis of a conventional cast.
If the grave was located before it was disturbed, expose the burial pit by removing the overburden with a trowel. Scraping with a trowel exposes differences in color, whereas sweeping with a soft brush shows differences in texture. Draw a plan of the surface features and topography. If the grave was disturbed by construction or other activities before it was recognized, clean all evidence in situ and document it before removal. If some of the surface features are still undisturbed, these should be recorded with great care to reconstruct the disturbed part of the scene.
Depending on the situation, it can be recommended that half of the feature fill should be excavated initially, without disturbing the grave pit. This can be accomplished by excavating some 5 cm away from where the walls of the shaft are expected to be and then poking at the remaining infill adhering to the wall with a sharp trowel. Usually the infill is dislodged in this manner without damaging the burial shaft. If any indications of tool marks exist in the walls of the burial pit, they should also be cast. Suitable roots should be sampled and recorded at this stage if they occur.
Excavation should follow natural strata if possible, otherwise it should be in horizontal arbitrary layers of 10-15 cm. If natural stratigraphy does occur, the excavation layers should not exceed 15 cm. Natural strata thicker than 15 cm should be divided in excavation spits. Collect a number of soil samples from the grave fill above the remains. Usually a soil sample from every spit is sufficient. Soil from the excavation should be screened.
All evidence found in the infill should be left in situ, or if impossible it should be thoroughly documented before removal. As soon as there are indications that the remains have been located, excavation should be stopped to record the profile of the section and the burial pit. The remains should be left covered with as much soil as possible in order to prevent damage to the bones during the rest of the excavation.
When all the remains have been located and the features of the grave documented, the rest of the grave fill can be removed. Excavation should always progress from the center towards the edges to avoid repeated brushing around bones which can dislodge them from their position. Burials in a forensic context are seldom very deep. In a deep grave, the excavation should be expanded if the remains have not been found at a depth where they can easily be reached from the surface. Usually more damage is done when the edge of the grave pit is collapsed by an excavator lying on the surface and reaching into the grave than by a controlled extension to the excavation. The extension should be planned so as to cause minimal damage to the walls of the burial pit, and all features of the pit should be recorded before it is sacrificed. The floor of the extension or trench must be deeper than the level on which the remains occur in the grave in order to avoid contaminating the burial pit. By extending the excavation a work area is created bringing the excavator within easy reach of the remains. A trench roughly in the middle of the grave, and wide enough for one person to sit in, is usually the best option (Fig. 3).
Once the remains are visible, the bones are exposed in the top-down manner and from the center to the edges. Again, all bones and associated physical evidence should remain in situ until documented and photographed (Fig. 4). A clear description of the orientation of the body and the burial position is recorded, drawn and photographed and soil samples from the abdominal cavity collected. All bones should be removed with care and securely packed after documentation. A test excavation conducted immediately below the level at which the remains were located will ensure that all evidence has been recorded and removed. The profiles and vertical shape of the grave pit should be recorded before the excavated area is refilled.
The same procedure can be used for intact and less-decomposed remains and in situations such as mass murder. These remains are always highly odorous. Excavators should take care to protect themselves by wearing gloves and protective clothing. The corpse should be put in a tagged body bag immediately.b
Extension of excavation to create work space for excavators.
Figure 3 Extension of excavation to create work space for excavators.
 Exposed human remains in situ. Note arrow, scale, date and other particulars indicated. 1-10, Detail indicated on photograph.
Figure 4 Exposed human remains in situ. Note arrow, scale, date and other particulars indicated. 1-10, Detail indicated on photograph.

Recovery of surface scatters

Not all remains are buried; in fact, most of the forensic remains are found on the surface. They may be scattered if the deceased wore summer clothing or might be better preserved in a winter outfit. In the case of scattered remains, the area should be walked systematically and carefully without stepping on any evidence. Every object should be flagged, but not removed before documentation. Care should be taken not to miss smaller objects such as a ring or tooth. Soil around larger pieces of bone can be screened after they have been removed.
When all possible pieces are located, the source from where the remains were scattered should be determined and the agent responsible for the scattering identified. In the case of dogs, for example, a knowledge of their habits may lead to the discovery of more remains. Ribs are very often dragged away by scavenging animals. Skulls may roll away if the body is on an elevated surface and therefore the lower reaches of the slope should be searched. Determining the path and direction of flow of water on a slope or in a valley may also lead to the discovery of more remains. The position of evidence and remains must be surveyed and indicated on a scale map of the locality (Fig. 5). They should also be labeled and their orientation noted. The same procedures used in buried body recovery apply in so far as the grid and documentation of the site is concerned. The area must also be tested with a metal detector to see if any metal objects (e.g. bullets) are on the surface or in the ground. As in the burial excavation, soil under the remains should be screened to locate smaller artifacts and skeletal fragments in case they are not visible.
The same kind of approach can be utilized for burned remains and mass disasters, but each case should, of course, be evaluated individually and the techniques adjusted accordingly.


One of the important principles in any excavation is the fact that it is destructive. Therefore, care should be taken to record all stages of the excavation by means of complete written notes, photographs and drawings. Photographs should be taken in both color and black-and-white. Each photograph should show the magnetic north and the scale. In practice, a small magnetic or blackboard works very well, on which the date, location, case number, orientation and depth can be indicated (see Fig. 4).
Sketch plan of a surface scatter. Note scale, north arrow and datum point.
Figure 5 Sketch plan of a surface scatter. Note scale, north arrow and datum point.
Specific observation must be made of whether the bones are articulated, which indicates that the body was most probably still intact when buried. The position of all limbs must be noted. Photographs taken should include images of the skeleton as a whole, as well as close-ups of any special finds. These finds are specifically marked to make them more visible on the photographs (see Fig. 4). Detailed notes which include the depth of the remains should be taken, and a scale diagram drawn of the grave from above and in cross-section. The depth below surface and the stratigraphy involved are also very important, and it may be necessary to draw the four profiles (east, south, west and north walls) of the grave.

Sampling at the scene

The matrix of the burial forms part of the evidence at the scene. The soil could have been mixed with chemicals, or pollen from the soil might be specific enough to trace the origin if the body had been transported over a long distance before it was buried. Trace evidence of poison and narcotics may also be preserved in the matrix. The only way to determine if these are present is by laboratory analysis of soil samples.
Plants occurring on the surface of the grave and in the surrounding area should be collected and pressed in a conventional plant press for analysis by a forensic botanist. It is sometimes possible to determine the postmortem interval by calculating the time it would take for a specific plant species to grow to the size of the collected specimens. Roots that were cut while the grave was being dug should also be collected from the profiles of the grave. By studying the ends and growth rings the forensic botanist can sometimes determine the season in which the root was damaged. Roots growing into the infill may also indicate the time that has elapsed since the grave was dug.
Insects, larvae and pupal cases should be collected and their location recorded. Insects flying in the vicinity of the body must also be collected. Live insects and larvae can be placed in small vials with a piece of damp cotton or tissue paper. It is necessary to collect live insects because it is sometimes difficult to determine the species from larvae. The live juveniles are hatched and the adult can then be classified. Insects should also be preserved at the time of collection to record the stage of development. This is done by placing them in vials filled with a suitable preservative. It is important to note where the insect was collected. An entomologist should be consulted to analyze the specimens.
Sampling for DNA analysis may be also necessary. Any bone that is enclosed by a volume of cortex, such as the body of a vertebra or a foot bone, may be suitable for this purpose. It is important to sample a bone that protects a part of itself from contamination and is also not needed for anthropological analysis. Samples for DNA analysis should be collected while wearing gloves, and bones that have been handled by the excavators should be avoided. DNA can also be obtained from teeth or cancellous bone such as the head of the femur, but this should only be done after the osteological analysis has been completed. The best samples, however, are those collected at the site to eliminate the problem of contamination.


Most of the procedures described are based on meticulous and systematic observation which should lead to the maximum amount of information and material retrieval. It should be re-emphasized that once the skeleton or an artifact has been removed, it can never be placed back into its original position. The most important aspect of the excavation is to provide a lead for the medicolegal investigators and police in order to identify the victim. Another aspect of such an excavation is to testify in court if necessary, and therefore the documentation must be complete and the chain of custody insured. Both modern and archaeological graves are valuable sources of information for forensic anthropologists. Repeated documentation, with the focus on context, by various means, e.g. photographs, videos and written descriptions, are crucial at all stages of the operation.
The chain of evidence should be maintained at all times, and the person in charge of the case must be aware of the whereabouts of all evidence including the remains at all times. All evidence should be signed for at all stages when they are handed over to the care of another person.
The advantages of systematic, scientific methods of excavation and documentation are obvious. If done properly, relevant information will be available permanently in case there is a need to reopen the case after some years. A scientific approach provides great accuracy in the collection of evidence and a higher probability that all physical evidence is collected, prevents postmortem damage to bones and artifacts, and decreases the probability of destroying contextual information.

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