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The use of geology in forensic investigations can help to compile an "environmental profiling" of a person, doing so it's possible to link the suspect to the scene of crime and provide circumstantial evidence for his guilt. It was in his fictional (but by real scientific progress inspired) cases of Sherlock Holmes that Sir Arthur Conan Doyle solved as first criminal cases by investigating soil evidence (for example in "A Study in Scarlet" and subsequent novels between 1887 - 1927).
At almost the same time the Austrian professor of criminology Hans Gross mentions in his "Handbuch für Untersuchungsrichter" (Handbook for Examining Magistrates, published in 1893) that the petrographic study of dirt on shoes probably can tell where a suspect went previously. Based on these ideas the France physician Edmund Locard in 1910 established the basic principle of environmental profiling (Exchange Principle):
"Whenever two objects come into contact, there is always a transfer of material. The methods of detection may not be sensitive enough to demonstrate this, or the decay rate may be so rapid that all evidence of transfer has vanished after a given time. Nonetheless, the transfer has taken place."
But it was the German chemist Georg Popp who in 1908 was the first investigator to solve the real murder of Eva Disch by considering soil as a evidence.
Popp reconstructed the movements of the suspect analyzing the dirt found on his shoes: the uppermost layer, thus the oldest, contained goose droppings and other earth materials that were comparable with samples in the walk outside the suspect's home. The second layer contained red sandstone fragments and other particles that were comparable with samples from the scene where the victim had been found. The lowest layer, thus the youngest, contained brick, coal dust, cement and a whole series of other materials that were comparable with samples from a location outside a castle where the suspect's gun and clothing had been found. The suspect affirmed that he had walked only in his fields on the day of the crime. Those fields were underlain by porphyry with milky quartz, but Popp found no such material on the shoes although the soil had been wet on that day, so he proved that the suspect was lying (MURRAY 2005).
In the last two decades the significance of forensic geology increased steadily, it is applied not only to connect single suspects to criminal cases, but also to trace the provenience of drugs or smuggled goods, including wildlife, explosive and reconstruct and uncover war crimes, not to mention the possible applications to detect cases against environmental law.
In 1997 the United Nations International Criminal Tribune for the Former Yugoslavia (UN ICTY) started exhumations of five mass graves in NE Bosnia associated with the massacre of civilians in and around Srebrenica in July of 1995. It was known from intelligence that 3 months after the initial executions of civilians the primary mass graves had been exhumed and the bodies transported over a 1-3 day period to a number of unknown, but at least 19, secondary grave sites.
Nevertheless to prosecute the suspects involved in the massacre during the process in The Hague, it was necessary to prove that the recovered bodies came from Srebrenica, and that the later dislocation of the graves was intentionally to hide the crimes. The two sites were intensively probed, and samples of the grave fills and surrounding soils and bedrock collected.
During sampling it must be considered that the decomposition of organic matter, in combination with groundwater, can create chemical reactions that alter the surrounding rocks and soils, it is also necessary to discriminate what should be sampled. For example, the surrounding undisturbed bedrock and covering soil should be examined separately. The soil itself can be subdivided, depending of bedrock, climate and soil-age in different pedogenetic horizons.
The material inside a refilled pit can consist of reworked soil or rocks from the underground or surrounding area, or material brought together with the corpses to the site.
The soil samples can be screened by their content of minerals and rocks, the size and form of single mineral or rock grains, biochemistry of humic substances, microbiology, invertebrates, plant macroremains and the small, but very abundant pollen and spores grains, diatoms. These parameters can vary in so many ways, that in practice every soil can be regarded as unique. Comparing the parameters between samples recovered from the victim or suspect and collected at the crime sites so can establish a connection between them.
For example during the investigations in Bosnia a striated clast of serpentinite found in one of the secondary gravesites proved a connection to a specific primary sites, only there a serpentinite dyke was outcropping. In a similar way the presence or absence of clay minerals, depending on the surrounding geology of the primary burial site, connected or excluded the primary to the secondary sites.
At almost the same time the Austrian professor of criminology Hans Gross mentions in his "Handbuch für Untersuchungsrichter" (Handbook for Examining Magistrates, published in 1893) that the petrographic study of dirt on shoes probably can tell where a suspect went previously. Based on these ideas the France physician Edmund Locard in 1910 established the basic principle of environmental profiling (Exchange Principle):
"Whenever two objects come into contact, there is always a transfer of material. The methods of detection may not be sensitive enough to demonstrate this, or the decay rate may be so rapid that all evidence of transfer has vanished after a given time. Nonetheless, the transfer has taken place."
But it was the German chemist Georg Popp who in 1908 was the first investigator to solve the real murder of Eva Disch by considering soil as a evidence.
Popp reconstructed the movements of the suspect analyzing the dirt found on his shoes: the uppermost layer, thus the oldest, contained goose droppings and other earth materials that were comparable with samples in the walk outside the suspect's home. The second layer contained red sandstone fragments and other particles that were comparable with samples from the scene where the victim had been found. The lowest layer, thus the youngest, contained brick, coal dust, cement and a whole series of other materials that were comparable with samples from a location outside a castle where the suspect's gun and clothing had been found. The suspect affirmed that he had walked only in his fields on the day of the crime. Those fields were underlain by porphyry with milky quartz, but Popp found no such material on the shoes although the soil had been wet on that day, so he proved that the suspect was lying (MURRAY 2005).
In the last two decades the significance of forensic geology increased steadily, it is applied not only to connect single suspects to criminal cases, but also to trace the provenience of drugs or smuggled goods, including wildlife, explosive and reconstruct and uncover war crimes, not to mention the possible applications to detect cases against environmental law.
In 1997 the United Nations International Criminal Tribune for the Former Yugoslavia (UN ICTY) started exhumations of five mass graves in NE Bosnia associated with the massacre of civilians in and around Srebrenica in July of 1995. It was known from intelligence that 3 months after the initial executions of civilians the primary mass graves had been exhumed and the bodies transported over a 1-3 day period to a number of unknown, but at least 19, secondary grave sites.
Nevertheless to prosecute the suspects involved in the massacre during the process in The Hague, it was necessary to prove that the recovered bodies came from Srebrenica, and that the later dislocation of the graves was intentionally to hide the crimes. The two sites were intensively probed, and samples of the grave fills and surrounding soils and bedrock collected.
During sampling it must be considered that the decomposition of organic matter, in combination with groundwater, can create chemical reactions that alter the surrounding rocks and soils, it is also necessary to discriminate what should be sampled. For example, the surrounding undisturbed bedrock and covering soil should be examined separately. The soil itself can be subdivided, depending of bedrock, climate and soil-age in different pedogenetic horizons.
The material inside a refilled pit can consist of reworked soil or rocks from the underground or surrounding area, or material brought together with the corpses to the site.
The soil samples can be screened by their content of minerals and rocks, the size and form of single mineral or rock grains, biochemistry of humic substances, microbiology, invertebrates, plant macroremains and the small, but very abundant pollen and spores grains, diatoms. These parameters can vary in so many ways, that in practice every soil can be regarded as unique. Comparing the parameters between samples recovered from the victim or suspect and collected at the crime sites so can establish a connection between them.
For example during the investigations in Bosnia a striated clast of serpentinite found in one of the secondary gravesites proved a connection to a specific primary sites, only there a serpentinite dyke was outcropping. In a similar way the presence or absence of clay minerals, depending on the surrounding geology of the primary burial site, connected or excluded the primary to the secondary sites.
Fig.2. The principle behind forensic geology is the assumption that rocks and trough erosion and alteration resulting soils, their properties and their combination are unique features of specific sites. Here an example for a typical soil with his pedogenetic horizons and some "complications":Fissures that act as sediment and also bone accumulation traps can develop not only in carbonates, but also in evaporitic sediments. Near the small village of Westeregeln (Thuringia, Germany) past quarrying activity for clay has exposed underlying Mesozoic gypsum and limestone formations, which in the upper part show an intensive “karst” network, refilled with Pleistocene sediments and fossils. The uppermost part of the stratigraphic column of the infilling sediments is represented by a postglacial soil, developed on Loess - aeolian sediment deposited during the last great glacial period. These sediments cover ancient matrix supported breccias, presumably generated by partial collapse of former caves or fissures. Note the secondary infillings of the burrows of animals and the different colors of the layers due their petrological and biological differences.
References:
BROWN, A.G. (2006): The use of forensic botany and geology in war crimes investigations in NE Bosnia.Forensic Science International 163: 204-210
PYE, K. (2004): Forensic Geology. In R.C. Selley, L.R.M Cocks and I.R Plimer (Ed.) Encyclopedia of Geology. Elsevier, Amsterdam
RUFFELL, A. & McKINLEY. (2005): Forensic geoscience: applications of geology, geomorphology and geophysics to criminal investigations. Earth-Science Reviews 69: 235-247
Online Ressources:
CHESELDEN, W. (1733): Osteographia, or The anatomy of the bones. - Fig.1.Frontispiece
MURRAY, R.C. (2005): Collecting Crime evidence from Earth.
it is nice to see a seciton on forensic geology. if you have mor e information regarding this please do send it to sukanya29@gmail.com.
ReplyDeleteI hope to dig into the subject again in the future - if time and interest allows. There are various books and especially assocation dealing with the topic.
ReplyDeleteIf there is interest you can contact me directly from my profile specifing what you are interested - I have to stick with my policy - to prevent spam I´m not sending e-mails only on comments request