Forensic archeology & Taphonomy of mass graves copy.pdf

DEPARTMENT OF ANATOMY AND FORENSIC ANTHROPOLOGY FORENSIC ARCHEOLOGY & THE TAPHONOMY OF MASS GRAVES ANA4204 - “There is a brief but very...

DEPARTMENT OF ANATOMY AND FORENSIC ANTHROPOLOGY FORENSIC ARCHEOLOGY & THE TAPHONOMY OF MASS GRAVES ANA4204 - “There is a brief but very informative biography of an individual contained within the skeleton, if you know how to read it…” - Clyde Snow. OBUN CLETUS AUGUST, 2023 INTRODUCTION - Forensic archaeology is the application of excavation and archaeological skills to forensic contexts. These skills include: - locating bodies - understanding the relationship between the grave and other buried features (e.g. soil layers, personal e ects, drainage ditches) - understanding what happens to the body in the ground (known as depositional and taphonomic processes). - Forensic archaeologists are also experts in excavating graves and creating detailed records of the relationships between objects, bodies/ skeletons and features within the burial environment. ff  INTRODUCTION… - The presence of signi cant numbers of bodies buried together often suggests a tragic and disturbing event – particularly in a forensic context – be it violence or natural disaster - During periods of rampant disease or natural disasters, mass graves may be used to dispose of the dead. - For example, during the Black Death (bubonic plague) pandemic of the 14th century, mass graves were common because of the overwhelming numbers of additional deaths fi LOCATING HUMAN REMAINS - The rst stage in locating grave sites within a forensic setting is to perform an intelligence-gathering exercise - This will take di erent forms depending on whether you’re looking for an individual body as a result of suspected homicide, or multiple bodies killed in a region of con ict. - In a disappearance or homicide case, police will gather information from witnesses as well as other relevant data to help narrow the search for an individual. fi ff fl DETECTION METHODS - Arial survey - Satellite imagery - Field-walking survey - Cadaver dogs  THE FORENSIC CONTEXT AND ANATOMY OF MASS BURIALS - The deliberate and legal burial of single cadavers in designated cemeteries is commonplace, whereas mass burials, as a means of disposal, tend to occur under extraordinary circumstances, for example mass burial sites due to tragedies such as famine, disease, disaster or war - The United Nations (UN), for example, developed a legal de nition to describe criminal disposal methods of multiple bodies of civilian victims in the war in the former Yugoslavia: - …locations where three or more victims of extrajudicial, summary or arbitrary executions were buried, not having died in combat or armed confrontations - Human rights in forensic anthropology refer to violations that go against the Geneva convention which place limits on actions during war. fi  DECOMPOSITION IN MASS GRAVES - Developing reliable or functional estimates of the PMI based on the degree of soft tissue preservation in mass graves is fraught with di culty because the mass grave creates its own microenvironment - Di erential preservation of human remains and artefacts in mass graves with the same post-mortem and post-burial - Some of the factors attributed to this phenomenon are a direct consequence of whether a particular body is within the mass or on the periphery (feather edge e ect), the presence or absence of clothing, the grave hydrological regime and contact with other materials - Fortunately, the broad categorization of whether buried remains are of forensic or archaeological signi cance can often be established using other indicators. For example, the dated stratigraphic context or the grave contents. ff ff fi ffi WHY DISTURB THE ALREADY INTERED? Developing a taphonomic pro le for a particular context can: - Help distinguish if remains are of archaeological or forensic signi cance; - assist in the development of estimations of time since death or burial; - help reconstruct past or palaeoenvironments; - determine any actions taken to conceal the victims’ identity or the crime; - identify patterns of behaviours; - Explain the factors and agents responsible for the survival, destruction and di erential preservation of physical remains and macromolecules (proteins, lipids, DNA); and - help establish the relative timing of peri-mortem versus post-mortem fractures and defects fi ff fi WILL THEY EVER REST IN PEACE? TAPHONOMIC PROCESSES AND DIFFERENTIAL PRESERVATION IN MASS BURIALS: CURRENT RESEARCH AND APPLICATION - Mant’s pioneering work in the 1950s on European WWII graves was the rst occasion to consider the variables at work in the decomposition of human remains in mass graves - The feather edge effect, states that bodies at the edges of a mass grave tend to exhibit accelerated decomposition in comparison with bodies in the centre of the mass. - Bodies at the centre are in intimate contact with one another and exposed to the interaction of Taphonomic factors and agents within the cluster of bodies. - In contrast, bodies on the periphery are exposed to the factors and agents at the interface between it, the deposit and the grave cut. fi CURRENT RESEARCH AND APPLICATION - The requirement to establish the identity of the dead generally falls into three main areas: - (i) criminal investigations resulting from homicide, unexplained natural deaths, or suicide; - (ii) non-criminal events resulting in single or multiple deaths; and (iii) war crimes investigations and genocide. - The latter category is covered under auspices of the 1949 Geneva Conventions governing the protection and amelioration of the wounded and sick involved in armed con icts, prisoners of war, and civilians in times of war fl PRIMARY MASS GRAVES - The primary deposition site is the location that a body is rst placed after death. - It may or may not be the place in which a person was killed. - If all of the bones are in the correct anatomical position, it implies that it is a primary burial - Primary mass graves that show signs of disturbance or alterations by robbers - The extent of disarticulation of those bodies in robbed graves can be as the result of putrefactive changes and the heavy machinery used to carry out the reinterment - fi SECONDARY MASS GRAVES - Secondary graves are characterized by commingled mass of bodies and body parts throughout the extent of the grave. - Physical evidence from within the graves, such as soil and pollen analysis, blindfolds and ligatures and shell cases can be used to establish links between the primary and secondary graves and timeline of events - The reason why bodies are usually moved is to hinder forensic investigations - An example of a secondary burial that most people are familiar with is an ossuary. - This is when skeletonised bodies are dug up in a churchyard to make space for more burials and selected bones from these bodies are stored within the church. - Please note that bones may also be disturbed by natural processes such as water and it’s important to di erentiate between these and human disturbance. - ff THE SILENT WITNESS… HOW DRY BONES CAN LIVE AGAIN! Establishing the cause and manner of death using osteometric methods  WHAT IS THEIR DIFFERENCE? - The cause of death is the speci c injury or disease that leads to death. - The manner of death is the determination of how the injury or disease leads to death. - There are ve manners of death - natural, - accident, - suicide, - homicide, - undetermined). fi fi EXCAVATION METHODS - Excavators need to have a knowledge of basic osteology (it is often best to involve an anthropologist as well as an archaeologist). - Excavators should be aware of the speci c di culties involved when excavating infant and juvenile remains. - Please note that ‘extra’ bones may sometimes be present. For example, extra ribs, vertebrae, or sesamoid bones (small round bones) in the hands or feet. - Two main methods used for excavation - Pedestal method - Stratigraphic method ffi fi PEDESTAL METHOD - The soil around the body mass is removed to just below the lower boundary of the grave, allowing complete viewing from all angles and access to all bodies along the outer margins and top of the grave. - The original grave walls and ramp are destroyed, but investigators do not have to stand on bodies during the excavation process since workers start at the outer boundaries and work inward. - This formation allows for water drainage from the site and more complete in situ photography while bodies are still in place. - The main disadvantage to this method is the loss of stability conferred by the earth surrounding the grave. If the central mass erodes, bodies and body parts can become displaced. STRATIGRAPHIC METHOD - The grave is treated as a single site: bodies and artifacts are excavated from top to bottom, removing evidence in reverse order to which it was deposited into the grave. - Grave walls and ramps are retained, leading to a better understanding of how the grave was constructed. Tool marks and tire tracks may also be recovered. - Due to the even lowering of the surface grave, rainwater can pool within the con nes of the grave, damaging exposed remains or eroding the body mass, but tents or shelters can be constructed over the grave to protect it during inclement weather. - Only bodies on the top of the mass can be accessed or viewed. - The bodies must be walked on by the investigators during the course of the excavation. fi WHICH IS BETTER? - Bones are separated from the body during both methods, although larger bones tends to be dissociated in the pedestal method and smaller bones in the stratigraphic method. Thus the stratigraphic method results in more complete body recoveries. - Decomposition tends to progress faster in bodies on the outer edges of the grave. The pedestal method exposes those bodies, leading to erosion of the mass and possible mixing of the remains. - Secondary or tertiary graves tend to contain more skeletonized remains and increased dissociation. Use of the pedestal method seems to accelerate slumping of the grave mass. - As a result, current scienti c opinion is that the stratigraphic method is preferable where possible. - fi  ANALYSIS OF COMMINGLED SKELETAL REMAINS - Commingled human remains can be defined as the mixing of the elements of multiple individuals into a single archaeological or forensic context. - This can occur through both natural and cultural mechanisms, and usually both will have an effect on the way archaeological assemblages can be examined - The primary categories of information used to sort commingled remains are - Biological profile, - Non-Human matching, - visual pair matching, - Osteometric sorting - Spatial analysis - DNA profile data.  IDENTIFICATION METHODS - Non-human material; Any non-human material should be removed from the commingled context. Such material may include animal bone, personal e ects and so on. Determination of non-human status is based on the shape, weight etc of the bones examined. - Spatial analysis; This method of associating body parts relies on the assumption that parts of a body will remain close to each other. Therefore minimum distances between matching body parts can suggest a relationship. - Visual pair matching; This method is based on the notion that bones from a given individual will show size, shape and colour similarities. This may be the case, but people can be quite asymmetric (e.g. have one leg shorter than the other) and the soil staining may di er across a single skeleton. It is often the long bones that are used for this approach. This method also relies on years of experience to improve the accuracy of assessments. ff ff OSTEOMETRIC SORTING - Osteometric sorting is the formal use of size and shape to sort bones from one another. The method relies heavily on measurement data and statistical models and is designed to maximize objectivity. - Osteometric sorting usually aids in documenting the Minimum number of individuals (MNI) - The MNI is a crude measure that calculates the minimum possible number of individuals represented by the skeletal elements obtained - This method is based on two things; - (I)that the human skeleton is largely symmetrical and therefore bones from the left and right side of the body will be approximately the same size; - (II) that articulating bones will be of comparable size in order to ‘fit’ together  ELEMENTAL COMPOSITION - The analysis of the distinctive chemical element compositions in bones in order to separate the bones of individuals is a new approach. - In particular, forensic practitioners have been interested in the potential of portable x-ray orescence – partly because it is a non-destructive method. - X-ray orescence in a method that res radiation into a sample and captures the energy released by the electrons from the atoms when excited. - The energy released correlates with elemental composition. fl fl fi IDENTIFICATION METHODS - Demographic features; Age and sex determination can help with separating bones out by person. For example, if you have multiple hip bones, whether they are from males or females can help you re ne your MNI. - Given that many mass graves associated with con icts include the remains of young males (soldiers) this technique doesn’t always provide the discrimination required - DNA; is unique in everyone but is challenging to use in a commingled grave context due to cross-contamination. It is also expensive and destructive. - In more complex commingled contexts, it would be common to use a range of methods to re-associate body parts. fi fl  WHAT HAVE WE LEARNED FROM HISTORY? - The observations from the Srebrenica genocide, the Rwandan genocide, the wars in the middle east and other cases highlights the evidentiary potential of Taphonomic assessment to reconstruct the past and relative chronologies, determine the actions taken to conceal the victims’ identity and the crime and explain the factors and agents responsible for the survival, destruction and di erential preservation of physical remains. - However, on its own, the condition and preservation of the human remains does little to assist in the development of estimations of time since death or burial ff