Forensic Geology in Military or Intelligence Operations

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Forensic Geology in Military or Intelligence Operations

█ WILLIAM C. HANEBERG

Forensic geology is strictly defined as the use of geologic principles and techniques to establish facts or provide evidence used in a court of law. A broader working definition includes the use of the same principles and techniques to establish facts or sequences of events regardless of whether they are used in court. Thus, the gathering and interpretation of geologic data for intelligence, espionage, and national security purposes can fall under the second definition of forensic geology. Forensic geology overlaps with the field of forensic soil science. In many cases, the work performed by practitioners in the two fields is very similar and the only distinction lies in the details of their academic training and professional experience. Also related is the field of forensic geophysics, in which geophysical instruments such as seismographs can be used as the basis for inferences about activities in remote or otherwise inaccessible areas.

Origin of forensic geology. The first written description of forensic geology is generally attributed to the fictional detective Sherlock Holmes, who was created by Arthur Conan Doyle (British, 1859–1930). In A Study in Scarlet, published in 1887, Holmes was endowed with the ability to easily distinguish soils of different types and infer from mud on their shoes and clothes the places to which people had traveled. He was also described by Dr. Watson, his fictional colleague, as having a "practical, but limited" knowledge of geology.

The first real use of forensic geology to solve a crime does not appear to have occurred until 1904, when a German chemist named Georg Popp used geologic evidence to help identify a murder suspect from a handkerchief containing traces of snuff, coal dust, and the mineral hornblende. The prime suspect used snuff, and divided his labors between a coal gasification plant and a quarry in which the rocks were rich in the hornblende. (Coal gasification was then a common process in which coal was transformed into natural gas.) Soil in the suspect's pant cuffs also was matched to soil at the crime scene and outside of the victim's home. Taken together, the evidence convinced the suspect to confess. Four years later, Popp was able to show that one layer of soil on the shoes of a murder suspect matched the soil and distinctly green goose droppings around the suspect's home. A second layer contained red sandstone fragments identical to those in the soil where the body was found. The third, and outermost, layer contained coal, brick, and cement dust identical to that found at the location where the murder weapon was found. The suspect claimed that he was walking in the fields near his home and therefore could not have committed the murder. Popp was able to show that, in addition to all of the geologic evidence that was preserved on the shoes, there was no sign of the distinctive milky white quartz particles that were characteristic of soil from those fields.

Methods of forensic geology. The methods used by forensic geologists are adaptations of the methods used by geologists engaged in academic research, mineral exploration, and other activities. For example, it is a fundamental principle of stratigraphy (the study of sequences of sedimentary rocks) that a layer of sedimentary rock is in most cases younger than the layers below it and older than the layers above it. This principle is known as the law of superposition. The implications for forensic geology are that a layer of mud deposited on shoes or an automobile is younger than the layers beneath it. Understanding the sequence of mud, sediment, or dirt layers can therefore allow forensic geologists to reconstruct a chain of events such as visits to several locations characterized by different soil or bedrock types.

Other techniques employed by forensic geologists are derived from the disciplines of petrography and petrology, which are concerned with the description and interpretation of rock types. Soils and rocks can be distinguished on the basis of their particle size distributions as well as the sphericity, angularity, and mineralogy of individual particles. Two samples of sand, for example, may be composed of grains that appear significantly different to an experienced geologist. Forensically important distinctions can sometimes be made with the unaided eye or a small magnifying lens. In other cases, binocular microscopes can be used to view grains using reflected light. A more elaborate method is the examination of thin sections using transmitted polarized light. Thin sections are made by gluing a soil or rock to a glass slide and then grinding it to a standardized thickness of 30 microns. Most minerals are transparent in thin section (although a few metallic minerals remain opaque) and can be identified by their crystal shape and the degree to which they distort light passing through polarizing filters placed above and below the thin section. Fragments of macrofossils and intact microfossils, as well as pollen, in a soil or rock can likewise be identified by microscopy.

Particles smaller than sand grains can be difficult to identify using optical microscopes, but their shape and surface texture can be examined using instruments such as electron microscopes. Another class of instruments known as electron microprobes can perform non-destructive chemical analyses, including mapping variations in chemical composition across grains much less than a millimeter in diameter. Electron microprobe maps of oxygen content, for example, might be used to determine whether two metallic mineral grains have experienced similar degrees of oxidation.

The origin and history of a soil or rock particle is known as its provenance. Geologists in general and forensic geologists in particular can infer whether the source of sand grains is likely to have been an igneous or sedimentary rock, whether the grains were likely to have been transported by running water or exposed in an arid environment, and the climate in which a soil was formed. The presence of rare minerals or distinctive microfossils may allow them to further limit the possible sources to a small geographic area, perhaps a single watershed or rock body described in a published map or report. Thus, establishing the provenance of sand or mud recovered as forensic evidence can place a suspect at a crime scene or confirm an alibi.

Forensic geology case histories. There have been several publicly known cases in which forensic geology has played an important role in espionage, intelligence, security, and military operations.

During the second half of World War II, the Japanese military developed a plan to attack the United States with unmanned balloons carrying explosive and incendiary bombs. Using meteorological observations and calculations, they were able to design balloons that could be launched from Japanese beaches and carried by the jet stream to the western United States. The balloons were designed to be self-regulating, releasing sandbags in order to gain elevation during cold nights and releasing hydrogen to loose elevation during warm days. It is believed that 9000 balloons were launched, of which an estimated 1000 reached North America. Two balloons drifted as far east as Michigan. Although they ignited a few small fires and killed only six people (five children and a minister's wife who came across an unexploded bomb while on a fishing trip in Oregon), their origin was of concern. It was not known whether the balloons were being launched from Japanese submarines, by shore parties that had landed on American beaches, from German prisoner of war camps, or from the internment camps to which many Japanese-American citizens had been forcibly relocated. Geologists in the military geology unit of the U.S. Geological Survey were asked to determine the launching point of the balloons from the provenance of sand that had been used for ballast and which had been recovered from many balloon crash sites. Because sand has a low economic value and is expensive to transport, it was likely that the source of the sand was at or near the launching areas. The geologists first eliminated North American sources for the sand, which contained an unusual combination of minerals, fossil and recent diatoms (single celled algae that secrete siliceous cell walls), foraminifera (single celled organisms with calcareous shells), mollusk shell fragments, and no coral. The absence of coral was important because coral grows only in warm water, meaning that the sand most likely came from a northern area. By comparing the sand to geologic maps and reports that had been published before the war, one as early as 1889, the geologists suggested two possible launching sites along the northern coast of Japan. In reality, balloons were being launched from three sites. One of them was a site identified by the geologists and the other two, separated by approximately 15 km, were close to the second site identified by the geologists.

Forensic geology has also been used to investigate politically motivated murders and terrorist attacks. Grains of sand and microfossils found on the body of Italian Prime Minister Aldo Moro, who was kidnapped and murdered by Red Brigade terrorists in 1978, led investigators to conclude that he had been held at least part of the time along an 11 km long stretch of beach north of Rome. The total mass of sand collected from Moro's clothing and the car in which his body was discovered was approximately 1 gram. The presence of bitumen (a tar-like substance in this case derived from oil spills dispersed by waves) and resins used in boat building further supported the beach hypothesis. Because of the high profile and political sensitivity of the case, collection of sand samples for comparison with the grains found on Moro's body occurred in secret. The geologist working on the case was accompanied by his wife, who posed as a tourist picking plants and observing the scenery while her husband surreptitiously collected sand samples.

The Federal Bureau of Investigation (FBI) relied heavily on geologic evidence to learn how the Mexico Federal Judicial Police (MFJP) attempted to cover up the murder of Drug Enforcement Agency (DEA) agent Enrique Salazar and pilot Alfredo Avelar, who assisted Salazar on clandestine missions for the United States government. Salazar had been kidnapped at gunpoint from the streets of Guadalajara, Mexico and his body was discovered, along with that of Avelar, after a shootout between the MFJP and family engaged in the drug trade. The entire family was killed in the shootout, and the implication was that Salazar had been kidnapped and killed by the family. Traces of soil on the bodies of Salazar and Avelar, however, did not match the soil at the ranch where the shootout occurred and caused suspicion to be cast on the explanation offered by the Mexican government. Detailed studies by an FBI geologist posing as a DEA agent (FBI agents were not allowed to work in Mexico, but DEA agents were) revealed an extremely uncommon assemblage of mineral grains and shards of pink volcanic glass. This geologic evidence led the investigators to a state park in mountainous terrain where, based on detailed examination of individual soil particles, the site at which Salazar and Avelar had originally been buried was discovered. Other forensic evidence showed that the MFJP had been involved in the kidnapping, torture, and burial of Salazar and Avelar.

Geologic interpretation of photographs and videotapes can also shed light on the location in which a photograph or a recording was made. A notable example of this kind of forensic geology occurred shortly after the September 11, 2001 terrorist attacks on the World Trade Center in New York City and the Pentagon in Washington, D.C. American geologists who had worked in Afghanistan were able to identify rocks in the background of a videotaped message from the terrorist leader Osama bin Laden, and therefore the region of the country in which the message was taped. The use of geologic knowledge to infer location was widely publicized, however, and subsequent messages were recorded against a cloth background in order to prevent the location of the taping from being discerned.

Knowledge of the principles of forensic geology can be used to obscure evidence or mislead investigators. Double agent Kim Philby (British, 1912–1988), who spied for the Soviet Union while at the same time working in the British intelligence service during the Cold War years, once used a small trowel to bury a camera in a wooded area near the Potomac River in Virginia. He then returned to his home and used the trowel to dig in his garden in order obscure any soil particles that might be used to identify the location of the camera. This incident would never have been known if Philby had not described it in his autobiography. Terrorists arrested in conjunction with the Aldo Moro case insisted that forensic evidence had been planted in order to steer authorities away from the true location of their activities, which might have led to the arrest of additional suspects. It appears, though, that the forensic evidence was authentic and reliable.

Forensic seismology. The use of geophysical methods, especially those derived from seismological studies of the Earth, can also provide information about remote events. Analysis of seismograms produced by the explosion of the Russian submarine Kursk in 2000, for example, have shown that a small initial explosion was followed by a much larger explosion that produced vibrations equivalent to those from a magnitude 4.1 earthquake. This information was used to infer that the size of the explosion was equivalent to that which would have been produced by 4000 to 6000 kilograms of TNT. Seismologists were also able to analyze information about the oscillations of a bubble of hot gas that rose through the sea after the explosion, and infer that the main explosion took place at a depth of approximately 100 meters. Bathymetric data suggest that the seafloor is about 100 meters deep at the explosion site, so it is likely that the second explosion occurred when the sinking submarine struck the seafloor.

Seismological data have also been used to help infer the details of 1995 bombing of the Murrah Federal Building in Oklahoma City, the 2001 World Trade Center attack, and the 2001 Pentagon attack. Analysis of seismograms associated with the collapse of the World Trade Center towers, for example, suggests that the actual structural collapse occurred over a period of about three seconds. The same principles can be used to obtain evidence of clandestine conventional or nuclear explosions, and in particular to verify that nuclear test ban treaties are not being violated.

Seismological data may provide information about the February 2003 disintegration of the space shuttle Columbia. The sonic boom produced as a shuttle descends is normally recorded on seismographs, but the seismogram produced by the final Columbia reentry does not contain evidence of a sonic boom. Although the reasons for this were unclear at the time this article was written, the seismic data provided enough information to allow the location of the disintegration to be calculated and compared against other observations.

█ FURTHER READING:

BOOKS:

Mikesh, Robert C. Japan's World War II Balloon Bomb Attacks on North America. Washington, D.C.: Farrar, Smithsonian Institution Press. 1990.

Murray, R. C. and J. C. Tedrow. Forensic Geology. Englewood Cliffs, New Jersey: Prentice Hall, 1998.

PERIODICALS:

Buck, S. "Searching for Graves Using Geophysical Technology: Field Tests with Ground Penetrating Radar, Magnetometry, and Electrical Resistivity." Journal of Forensic Sciences, vol. 48, no. 1 (2003): 5–11.

Holzer, T. L., J. B. Fletcher, G. S. Fuis, T. Ryberg, T. M. Brocher, and C. M. Dietel. " Seismograms Offer Insight into Oklahoma City Bombing." Eos, Transactions American Geophysical Union, vol. 77, no. 41 (October 8, 1996): 393, 396–397.

Koper, K. D., T. C. Wallace, S. R. Taylor, and H. E. Hartse. "Forensic Seismology and the Sinking of the Kursk." Eos, Transactions, American Geophysical Union, vol. 82, no. 4 (2001): 37.

Lombardi, Gianni. "The Contribution of Forensic Geology and Other Trace Evidence Analysis to the Investigation of the Killing of Italian Prime Minister Aldo Moro." Journal of Forensic Sciences, v. 44, no. 3 (1999): 634–642.

McPhee, John. "Annals of Crime—The Gravel Page." The New Yorker. (January 29, 1996): 44–69.

ELECTRONIC:

American Society of Forensic Geologists." American Society of Forensic Geologists." 2002. <http://www.forensicgeology.org/>(13 March 2003).

Levine, Alissa. "Secrets Hidden in Soil." September 5, 2001. <http://ltpwww.gsfc.nasa.gov/globe/forengeo/secret.htm>(13 March 2003).

Murray, Raymond. "Devil in the Details, the Science of Forensic Geology." January 29, 2003. <http://www.forensicgeology.net/science.htm>(13 March 2003).

Pinsker, Lisa M. "Geology Adventures in Afghanistan." Geotimes Web Feature. February 2002. <http://www.agiweb.org/geotimes/feb02/Feature_Shroderside.html>(13 March 2003).