Tools In Forensic Archaeology

Introduction

Forensic archaeology is an interdisciplinary field that merges the principles of archaeology with the methodologies of criminal investigation. This specialised discipline is focused on locating, recovering, and analysing evidence related to criminal cases, particularly those involving human remains. By employing a variety of tools and techniques, forensic archaeologists work meticulously to uncover buried artifacts, bodies, and contextual information critical to understanding past events.

With advancements in technology, forensic archaeology has expanded to include non-invasive methods, such as ground-penetrating radar (GPR) and LIDAR, which allow for the detection of hidden features beneath the soil without disturbing the site. This blend of traditional excavation practices and innovative technological approaches enables investigators to piece together narratives from the past while ensuring that the integrity of the evidence is maintained.

Excavation and Recovery Tools

As soon as a burial site has been anticipated, forensic archaeologists use different devices for excavation and evidence recovery:

• Basic excavation tools: Shovels, trowels, brushes, and picks are used to remove soil and debris.
• Screening equipment: Fine-mesh sieves help to reclaim minute artifacts as well as bone fragments during sifting through soils.
• Photography and documentation equipment: Cameras, measuring tapes and drawing equipment are thus vital in recording the excavation process and evidence location.
• Global Positioning System (GPS): GPS technology aids in the precise determination and mapping out such evidence.
• Anthropometric tools: calipers, osteometric board, among other measurement tools, are used when taking dimensions.
• Tweezers, vials, plastic bags, and core samplers are other standard equipment that can be used.

Non-Invasive Tools

Before excavating, forensic archaeologists often use non-invasive techniques to locate potential burial grounds or areas of interest; these tools include:

1. Ground-penetrating radar (GPR)

This non-destructive geophysical technique uses electromagnetic pulses to provide a subsurface image. The pulses are sent into the ground, and the returned signals are recorded. Differences in soil composition and objects beneath the surface result in variations in these returned signals, ultimately forming a radargram which can be interpreted in terms of likely archaeological features. In forensic archaeology, GPR has been beneficial in finding buried human remains, clandestine graves, and any associated artefacts. A systematic scan of the surface can be conducted to see any anomalies that may indicate the presence of a feature made by humans.

The GPR technology is composed of an antenna that sends electromagnetic waves into the ground and a receiver that reads and records the responses of the waves. Whenever the waves come to any materials or objects underground, the signals are reflected, refracted or absorbed. The time taken for the reflections to get back to the surface is recorded. The depth of the buried object can be determined from the recorded times.

Possible anomalies to a sewer line that GPR can detect are changes in soil composition, such as backfill, subsidence or other subsurface phenomena, or local structures/ voids/ reactors that are being picked up as anomalies.

Body discovery: GPR has been used in various forensic situations, from mass graves to single burial sites or other clandestine scenes of crime, to detect hidden graves. Subsurface disturbances and anomalies help investigators employ the GPR system to identify possible body locations that they can target for further excavations. Also, burial locations may be misinterpreted by the variability of conditions within pre-existing GPR data in many archaeological cemeteries, as well as populations that are interred.

Burial site mapping: GPR can be efficiently used in the search for historical human interments and for mapping them out of the ground surface with the highest rate of success, especially when combined with geophysical, forensic, archaeological and anthropological investigations. GPR rapidly provides high-resolution spatial data (i.e. ‘maps’) of sub-surface traits qualitatively similar to remote-sensing analysis, which, combined with historical aerial imagery and other resources, support archeological studies and other human occupation and use of the earth. Such information is used for spatial questions, databases, municipal archives register, ethnographic data, historical photos with aerial vertical photographs, and other studies combining social science and physical sciences.

Leading Crime Scene Investigation: There are multiple examples of GPR exploration of crime scenes, such as outdoor murder scenes and clandestine laboratories. GPR systems can detect buried objects, metal, plastic, ceramic, and organic materials, as well as dead bodies.

Search after a disaster: In the event of earthquakes or mass casualty events, GPR would help to locate victims and determine what resources will be required to support the relief mission. Also, GPR can rapidly survey large areas without geologists on foot, which is particularly important in hazardous situations, rugged terrain, or during an ongoing search. GPR experiments prior to and after the crisis can evaluate the extent of destruction caused by an earthquake or other disaster, surrounded by an opportunistic five-fold increase in study scope and then focal developments. The increasing availability of LiDAR data (tens of terabytes per country) is another asset for future regional studies of GPR complementary to ground-based measurements. Several GPR units are available commercially for use in the field. This same capability may allow specific criminal units to do autopsies on the spot before an autopsy.

2. Magnetometry

It involves measuring changes in the Earth’s magnetic field resulting from underground disturbances such as buried objects or human remains.

• Magnetic anomalies from buried ferrous objects can be detected using a magnetometer, such as iron-containing materials in coffins, weapons, and tools. These are then represented as data variation, typically represented on color-enhanced maps.
• Fluxgate magnetometers measure changes in magnetic field intensity and are very sensitive. It is commonly used in detailed surveys over small areas.
• Proton precession magnetometers have a lower sensitivity than fluxgate but offer a more excellent range of measurements and are commonly used for preliminary site surveys.
• Optically pumped magnetometers are relatively new but of high sensitivity and speed, and so lend themselves to rapid surveys over large areas.

3. LIDAR (light detection and ranging)

These systems incorporate a laser transmitter, a receiver and a GPS unit. This laser emits light pulses that eventually hit the ground objects. The length of time it takes for light to reflect back to the sensor is measured to determine the distance. Using an integration of these measurements with the data obtained by GPS, the LIDAR systems record extremely accurate DEMs and point clouds.

• LIDAR is exceptionally effective in picking out potential archaeological sites, but those related to forensic investigations are not exempted. This would eliminate the visual noise from vegetation and bring out very slight topographic features that may indicate buried structures, ditches, or crop marks indicative of human remains or associated artifacts.
• LIDAR can be used to create detailed 3D models of crime scenes, which then preserve the evidence in an exact and permanent format.
• Vegetation penetration allows LIDAR to detect underground features, whether buried structures, graves or other hidden objects. This makes the technology very useful when trying to identify clandestine burial sites or recover hidden evidence.

4. Aerial photography and remote sensing

It allows high-resolution images with the ability to detect changes like vegetation patterns or soil discoloration that could indicate buried bodies.

5. Geographic Information Systems (GIS)

Software applications for mapping and analysing spatial data that help in site selection, data management, and visualisation.

Case Studies

A good example of how LIDAR can be applied in forensic archaeology is the site of La Cotte de St. Brelade on the island of Jersey. This Palaeolithic cave site has been found to yield significant archaeological and paleontological remains from the evidence of Neanderthal occupation. In the surroundings, a high-resolution digital terrain model was created using LIDAR. It helped researchers identify subtle topographic features of the area, such as buried channels and depressions, that were earlier obscured by vegetation. These provided crucial clues to the environment at the site and its potential archaeological significance. In combination with ground-based investigations, such LIDAR data have allowed archaeologists to determine locations of interest to excavate. This targeted approach first provides for the most efficient use of fieldwork time while risking the least amount of damage to sensitive archaeological deposits.

In another case study of research on the application of GPR for the disclosure of subsurface remains of the Wurttemberg-Stambol Gate in Republic Square, Belgrade, Serbia, is presented. In that sense, GPR investigations were carried out in the square within the general renovation works comprising rearrangement of traffic control, expansion of the pedestrian zone, renewal of surface layers and valorisation of existing archaeological facilities. Historical documents and data from previous restoration works suggested the presence of the gate remains. A pulsed radar unit was used for the survey, with 200and 400-MHz central frequency antennas. Data were recorded over a grid and two three-dimensional models were built, one for each set of antennas. The grid was the same for both sets of antennas, therefore the two models could be compared. A number of horizontal cross sections of the models were plotted at different depths. These images were closely inspected and interpreted, trying to find signatures that could be related to the presence of the searched archaeological structures. Reflections arising from the gate remains were found with both models in the same area of the surveyed space and at the same depth; geometry, size, and layout of the gate columns, as well as of other construction elements belonging to the gate, were determined with excellent accuracy. Archaeological excavation works in the region where the foundation remains were estimated to be, according to the GPR findings, were carried out, and remains were present with various columns and side walls. This case study shows and further proves the effectiveness and reliability of GPR for the non-invasive prospection of archaeological structures hidden in heterogeneous subsurface urban environments. The authors are of the opinion that GPR should become a routine procedure for the construction and renovation field in historical cities.

Conclusion

The considerable toolkit involved in forensic archaeology, where archaeology meets criminal justice, gives access to the truth. The inventory, from traditional excavation tools to state-of-the-art technologies like ground-penetrating radar and LIDAR, is an instrument underpinning the investigator in the meticulous exploration of crime scenes and human remains and reconstructing activities conducted in the past. As long as challenges such as environmental factors and the general complexity of the evidence are here to stay, further development and fine-tuning of these tools will continue to revolutionize the ability of the field. Just like technology will keep moving forward, forensic archaeology will go with the flow in its use in solving crimes and hence allowing closure to the deceased and their loved ones. Forensic archaeologists contribute much in the bid for justice through their emphatic attention to detail in the field, coupled with highly advanced means of analysis.

References

• Adovasio, J.M. (2005). Forensic archaeology: An introduction. Academic Press.
• Butler, K. E. (2005). Forensic Archaeology: An Introduction. Cambridge University Press.
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• Forensic archaeology. (2021, July 15). SlideShare. https://www.slideshare.net/slideshow/forensic-archaeology/249754307
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• National Park Service. (n.d.). Ground Penetrating Radar (GPR). https://www.nps.gov/articles/permits_information-for-nps-archeologists.htm
• Ristic, A., Govedarica, M., Pajewski, L., Vrtunski, M., & Bugarinovic, E. (2020). Using Ground Penetrating Radar to Reveal Hidden Archaeology: The Case Study of the Wurttemberg-Stambol Gate in Belgrade (Serbia). Sensors, 20(3), 607. https://doi.org/10.3390/s20030607
• Sauer, N. J. (2001). Practical human osteology in forensic taphonomy. CRC Press. Ubelaker, D. H., @Scammell, H. M. (2012). Forensic taphonomy: The postmortem fate of human remains. CRC Press.

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