HOME    THE SCIENCE    SERVICES  BOOK  RESUME  CONTACT                                                                                                                                                                    


Raymond C. Murray                                Geotimes January 2005



          As with so many other types of criminal investigation, forensic geology began with the writings of Sir Arthur Conan Doyle, who wrote the Sherlock Holmes series between 1887 and 1927. He was a physician who apparently had two motives: writing salable literature and using his scientific expertise to encourage the use of science as evidence.

            In 1893, Hans Gross, an Austrian forensic scientist, wrote the book Handbook for Examining Magistrates, in which he suggested that      perhaps the dirt on someone's shoes could tell more about where a person had last been than toilsome inquiries.

It was only a matter of time before these ideas from an author of fiction and criminalists' handbook would appear in a courtroom.

A century later, the use of geologic materials in criminal and civil cases is common­place. Public and private laboratories for analyzing soils and related     materials include the FBI laboratory in the United States, La Polizia Scientifica in Italy, the Centre of Forensic Sciences in Toronto, the National Institute of Police Science in Japan, Microtrace in the United States and many others.

Forensic geology studies vary in scope. A common type of investigation involves identifying a material that is key to a case - for example, examining pigments in a painted picture or material in a sculpture when authenticity or value is at issue. Identification is also important in questions of mining, mineral or gem fraud to determine if the material is what its sellers claim it to be. And identification of fire-resistant safe insulation on a person or individual's property may provide probable cause for further investigation.

Beyond identification, forensic geologists can also look at the origin of particular material. Here the examiner needs a broad knowledge of the geology and the best geologic and soil maps to answer questions. For example, if the soil on a body does not match the location where the body is found, from where was the body moved? Similarly, examiners can compare two samples, one associated with the suspect and the other collected from the crime scene, to see if they had a common source: Does the soil on the suspect's shoe compare with the soil type collected at the crime scene, for example?

Another new developing area of forensic geology is its use in intelligence work. A person, for example, may claim to have never been to a particular location, but is then found with rocks from that spot, thus linking the individual to a geographic location. Remember the outcrop you saw behind Osama bin Laden on TV after September 11. What was the location? A geologist who has done field work in the area would be able to locate that outcrop, and that actually happened: Geologist John Shroder was able to identify the region where bin Laden had been sighted in Afghanistan in 2001 (see Geotimes, February 2002). Geologic evidence rarely provides a unique solution for which the geologic mind cannot imagine another possibility. But there are some exceptions, as illustrated by the following two cases.




          The murder of John Bruce Dodson produced one of the most interesting cases in the entire history of forensic geology. Here, the geologic evidence is unequivocal in that it tied the suspect directly to the crime and eliminated the suspect's alibi. Most importantly, the investigator of the crime recognized the potential importance of the geologic evidence and arranged for the examination of that evidence. The testimony of the forensic geologist was critical to the prosecution of the case. The case began on Oct. 15, 1995, when John Dodson was found dead while on a hunting trip with his wife of three months, Janice. The scene was a crisp autumn morning high in the Uncompahgre Mountains of western Colorado.

         At first glance, it appeared to be a hunting accident. However, the autopsy revealed two bullet wounds to the body and one bullet hole through John's orange vest. Western Colorado District Attorney Frank Daniels points out in his book on the case, Dead Center, that if there had been only one bullet, there never would have been an investigation and the death would have been ruled an accident.

        The investigation showed that the Dodsons were camped near other hunters, one of whom was a Texas law enforcement officer. He responded to Janice's frantic call that her husband had been shot. She was standing about 200 yards from the camp in a grassy field along a fence line. The officer determined that John was dead and started the process of getting help. Prior to calling for help, Janice had returned to her camp and removed her hunting coveralls, which were covered with mud from the knees down. She later told investigators that she had stepped into a mud bog along the fence near camp. Investigators found a .308-caliber shell case approximately 60 yards from the body. In addition, they found a .308-caliber bullet in the ground on the other side of the fence, which created a direct line from the location of the case to the body to the bullet.

       Janice's ex-husband, J. C. Lee, was also camped three-quarters of a mile from the Dodsons. Janice knew the site was his favorite camp location. He naturally came under suspicion. However, Lee was hunting far away from camp with his boss at the time of the shooting. Most importantly, Lee reported to investigators that while he was out hunting, someone had stolen his .308 rifle and a box of .308 cartridges from his tent. Winter comes early at 9,000 feet in the Umcompahgre, and little more could be done at the scene. However, investigators Bill Booth, Dave Martinez and Wayne Bryant returned during the summers of 1996, 1997 and 1998 and searched for the rifle and other evidence. They tried to search every place a weapon could have been hidden. They combed the entire area, including ponds, with metal detectors in hope of finding the rifle; it has never been found. During the final search of the pond near Janice's ex-husband's camp, Al Bieber of NecroSearch International (a nonprofit consulting company for law enforcement agencies) commented that the mud in and around a cattle pond near Lee's camp was bentonite, a clay that someone brought to the pond to stop the water from seeping out of the bottom. That evening, Booth and Martinez were camped near the crime scene. They were discussing the evidence in the case when investigator Booth said, "The mud." He was referring to the dried mud that was found on Janice Dodson's clothing. If Janice had obtained the rifle from Lee's camp, she would most likely have stepped or fallen into the bentonite clay that drained across the road from the cattle pond. Remembering Janice's statement that she was returning to camp on the morning of the crime and stepped into a mud bog near her camp, Booth and Martinez decided they needed to obtain dried mud samples from the bog near the Dodsons' camp, the area around a pond nearby the camp, and the human-made pond and runoff near Lee's camp.  

         Booth and Martinez packaged the dried mud from each location and sent the samples along with the dried mud that had been recovered from Janice's overalls to the laboratory section of the Colorado Bureau of Investigation in Denver, where it was examined by Jacqueline Battles, a forensic scientist and lab agent. Battles is a highly respected forensic scientist with considerable geologic training, who, like many of the others in the profession, got her early training with Walter McCrone. She concluded and later testified to the fact that the dried mud found on Janice Dodson's clothing was consistent with the dried mud recovered from the pond near Lee's camp. The dried mud that had been recovered from Janice's overalls was found not to be consistent with the mud bog or the pond near her camp. This was a breaking point in the case that allowed Booth and Martinez to put Janice Dodson in her ex-husband's camp around the time his rifle had been stolen. There are no other bentonite-lined ponds in the area and no bentonite deposits.

          Booth and Martinez went to Texas and served an arrest warrant on Janice. She was extradited to Colorado, tried in court and convicted in the murder of John Bruce Dodson. The jury understood the results that followed Booth's insightful "mud" exclamation. Janice is now serving a life sentence without the possibility of parole in Colorado's state prison for women. The mud samples collected from Janice's clothing are still in the sheriff’s office evidence room where they have been since 1995.



 A pond with bentonite in the Uncompahgre Mountains of western Colorado revealed key geologic evidence that incriminated Janice Dodson in the murder of her husband John Bruce Dodson




A case that illustrates many of the Issues comparing soil and related material occurred in Canada a few years ago. The body of eight-year-old Gupta   Rajesh was found alongside a road outside of Scarboro, Ontario. The back of his shirt had a smear of oily material, and the preliminary conclusion was that he was the victim of a hit and run accident, with the oily material coming from the undercarriage of a vehicle. But examination of the oily material and the particles suspended in it by forensic geologist William Graves of the Centre of Forensic Sciences in Toronto told a different story.

Investigators had collected samples of oily material on the floor of an indoor concrete parking garage where a suspect, Sarbjit Minhas, parked her Honda automobile. Analysis of the samples showed that the sand and other particles within the oil from the victim's clothes and the park­ing garage were similar. Analysis of the oil from the victim's shirt and garage floor showed them to be both similar and different from oil collected on the floor of 10 other garages in the area.

Particles in samples from the victim's clothes and the suspect's parking place provided considerable information. The sand from both samples was sieved, and subsamples produced of the various size grades for the two samples. When compared after the oil had been removed, the color of each pair of subsamples was identical.

            Additionally, the heavy minerals in both samples were similar, and three distinct kinds of glass were found in the two samples: amber glass, tempered glass and lightbulb glass. Each of the different glasses was identical in refractive index value (the amount a ray of light bends when passing through the glass into another medium). Small particles of yellow paint with attached glass beads were found in both samples. This type of paint is often found on center stripes of highways and reflects light.

Graves concluded that there was a high probability that the body of Gupta Rajesh had been in contact with the concrete floor of the garage at the place where the suspect parked her car. Interestingly, the same oil and particles were found in the suspect's Honda. Whether the oil and particles on the victim came from inside the vehicle or the floor of the garage, the presence and distinctiveness of the samples still strongly associated those two areas with the victim.

Minhas was tried in the Superior Court of the Province of Ontario in November 1983 and convicted, with help from testimony by Graves.

            This case illustrates an important concept in the presentation of soil evidence and perhaps all physical evidence, except DNA. We have become awed and impressed by the high probabilities that result from DNA evidence. Some people expect that other types of evidence should have similar statistical information. But in the Minhas case, we see a conclusion based on at least 10 different materials and observations. Because we do not know the probability of a tempered glass fragment, a particular group of heavy minerals, or sand of the same color being on a particular parking place in a concrete garage in Scarboro, Ontario - and in all likelihood we will never know - a frequency statistic cannot be generated. A useful database of sands, particles, glass, oils and heavy minerals would be too difficult to generate. ~ Additionally, it may not apply to any one  specific case because of the variability of mineral particles - the very distinctiveness that makes geologic materials such good evidence. Thus, we rely on the skilled and honest examiner to reach a conclusion expressed in words rather than in numbers to inform the jury or judge so that they can reach a verdict. In this way the expert is a teacher, instructing the judge, attorneys and jury in the basic concepts and premises that allow them to do the work they do. The triers of fact must be schooled in the methods of production of the evidence (how light bulb glass is made, for example), the procedures used to analyze it, and what makes the evidence significant. That understanding will lead the courts to an appreciation of unquantifiable evidence and give the jury a basis for weighing its significance.

Geologic evidence will continue to be developed and presented in courtrooms around the world. The quality of evidence collection and examination will improve, and new methods will be developed. The results will be to the benefit of justice.




Oil and debris collected from an indoor parking garage floor such as this one helped convict a suspect in the murder of a young boy in Scarboro, Ontario




        A recent case does not fit the pattern of most soil evidence, but clearly illustrates the contribution being made by forensic geologists. Washington State Patrol Forensic Geologist Bill Schneck became involved in the investigation into the serious illness of a small child caused by arsenic poisoning. The suspected person was absolved when an examination of the child's house revealed a number of mineral specimens left in the house and the yard by a former occupant who was a mineral collector. Many of those specimens were arsenopyrite, an iron arsenic sulfide. The child had been eating and chewing on the material. This case is a good reminder that lead is not the only material that can cause health problems in children.




Forensic Geology: Yesterday, Today and Tomorrow


Raymond C. Murray


Arthur Conan Doyle and Hans Gross suggested the possibility of using soil and related material as physical evidence. Edmond Locard provided the intellectual basis for the use of the evidence. High visibility cases such as the work of the FBI in the Camarena case, the laboratory of the Garda Siochana in the Lord Montbatten case and G. Lombardi in the Aldo Moro case contributed to the general recognition that geological evidence could make an important contribution to justice. The value of geological evidence results from the almost unlimited number of rock, mineral, soil and related material kinds combined with our ability to use instruments that characterize these materials. Forensic examinations involve identification of earth materials, comparison of samples to determine common source, studies that aid an investigation and intelligence studies. The future will see increased use of the evidence, new automated methods of examination, improved training of those who collect samples, research on the diversity of soils and how, when and what parts of soils are transferred during various types of contact.  The microscope will remain important because it allows the examiner to find the rare and unusual particle.


          The use of geological materials as trace evidence in criminal cases has existed for approximately one hundred years.  Murray (2004) provides an overview and reminds us that it began, as with so many of the other types of evidence, with the writings of Sir Arthur Conan Doyle.  Doyle wrote the Sherlock Holmes series between 1887 and 1927.  He was a physician who apparently had two motives: writing salable literature and using his scientific expertise to encourage the use of science as evidence (Murray and Tedrow 1992).  In 1893 Hans Gross wrote his book Handbook for Examining Magistrates in which he suggested that perhaps one could tell more about where someone had last been from the dirt on their shoes than from toilsome inquiries.  A German chemist, Georg Popp, in 1908 examined the evidence in the Margarethe Filbert case.  In this homicide a suspect had been identified by many of his neighbours and friends because he was known to be a poacher.  The suspect's wife testified that she had dutifully cleaned his dress shoes the day before the crime.  Those shoes had three layers of soil adhering to the leather in front of the heel.  Popp, using the methods available at that time, said that the uppermost layer, thus the oldest, contained goose droppings and other earth materials that compared with samples in the walk outside the suspect's home.  The second layer contained red sandstone fragments and other particles that compared with samples from the scene where the body had been found.  The lowest layer, thus the youngest, contained brick, coal dust, cement and a whole series of other materials that compared with samples from a location outside a castle where the suspect's gun and clothing had been found.  The suspect said that he had walked only in his fields on the day of the crime. Those fields were underlain by porphyry with milky quartz.  Popp found no such material on the shoe although the soil had been wet on that day.  In this case, Popp had developed most of the elements involved in present day forensic soil examination.  He had compared two sets of samples and identified them with two of the scenes associated with the crime.  He had confirmed a sequence of events consistent with the theory of the crime and he had found no evidence supporting the alibi.

Rocks, minerals, soils and related materials have evidential value.  The value lies in the almost unlimited number of kinds of materials and the large number of measurements and observations that we can make on these materials.  For example, the number of sizes and size distributions of grains combined with colors, shapes and mineralogy is almost unlimited.  There are an almost unlimited number of kinds of minerals, rocks, and fossils.  These are identifiable, recognizable, and can be characterized.  It is this diversity in earth materials, combined with the ability to measure and observe the different kinds, which provides the forensic discriminating power.

There have been many contributions to the discipline over the last 100 years.  Many have been made by the Laboratory of the Federal Bureau of Investigation, in Washington D C., McCrone Associates in Chicago, The Centre for Forensic Sciences in Toronto, Microtrace in Elgin, Illinois, the former Central Research Establishment at Aldermaston,  Kenneth Pye Associates Ltd in Great Britain, The Japanese National Research Institute of Police Science, The Netherlands Forensic Institute, as well as other government, private and academic researchers.

Because much of the evidential value of earth materials lies in the diversity and the differences in the minerals and particles, microscopic examination at all levels of instrumentation is the most powerful tool.  In addition, such examination provides an opportunity to search for man-made artifact grains and other kinds of physical evidence.

Individualization, that is, uniquely associating samples, from the crime scene with those of the suspect to the exclusion of all other samples is not possible in most cases. In this sense earth material evidence is not similar to DNA, fingerprints and some forms of firearms and tool mark evidence.  However, in a South Dakota homicide case, soil from the scene where the body was found and from the suspect’s vehicle both contained similar material including grains of the zinc spinel gahnite. This mineral had never before been reported from South Dakota.  Such evidence provides a very high level of confidence and reliability.

One of the most interesting types of studies is the aid to an investigation.  There are many examples of cases where a valuable cargo in transit is removed and rocks or bags of sand of the same weight are substituted.  If the original source of the rocks or sand can be determined, then the investigation can be focused at that place.  In a high visibility case, DEA agent Enrique Camarena was murdered in Mexico (McPhee 1997).  His body was exhumed as part of a cover-up staged by members of the Mexican Federal Judicial Police.  When the body was found later, it contained rock fragments that were different from the country rock at that place and represented the rocks from the original burial site.  With the combination of petrographic examination of those rocks and a detailed literature search of Mexican volcanic rock descriptions, the original burial location was found and the cover-up exposed.

Most examinations involve comparison.  Comparison aims to establish a high probability that two samples have a common source, or conversely that they do not have similar properties and thus are unlikely to have come from the same source.  In comparison studies of soils, it is difficult to overestimate the value of findings artifacts in the soil or some other unusual type of evidence.  In an Upper Michigan rape case, three flowerpots had been tipped over and spilled on the floor during the struggle.  It was shown that potting soil on the suspect's shoe had a high degree of similarity with a sample collected from the floor and represented soil from one of the pots.  In addition, small clippings of blue thread existed both in that flowerpot sample and on the shoe of the suspect.  The thread provided additional trace evidence which supplemented the soil evidence.

In a New Jersey rape case, the suspect had soil samples in the turn-ups of his trousers.  In addition to glacial sands grains that showed similarity with those in soil samples collected from the crime scene, the soil contained fragments of clean Pennsylvania anthracite. Such coal fragments are not uncommon in the soils of most of the older cities in eastern North America. However, in this sample there was too much coal when compared with samples collected in the surrounding area.  Further investigation showed that some 60 years earlier the crime scene had been the location of a coal pile for a coal burning laundry.  Again, the combining of soil-evidence with an investigation of an artifact and local industrial history increased the evidential value.

A new and evolving type of study is one done for the purpose of intelligence gathering. An example might involve identifying mineral material on an individual who had claimed to have recently been to a particular location.  In such a case the question would be asked whether the mineral material supports the claim and could have come from that location.  Identification of the mineral material alone can be useful in the case of mine fraud, gem fraud and art fraud by providing information that demonstrates the fraud.

The alertness of those who collect samples, and the quality of collection, is critical to the success of any examination.  If appropriate samples are not collected during the initial evidence gathering, they will never be studied and never provide assistance to the court.  There is the case in which an alert police officer happened to look at an individual arrested for a minor crime.  He observed, "that is the worst case of dandruff I have ever seen."  It was not dandruff but diatomaceous earth, which was essentially identical with the insulating material of a safe that had been broken into the previous day.

The future of Forensic Geology holds much promise.  However that future will see many changes and new opportunities. New methods are being developed that take advantage of the discriminating power inherent in earth materials.  Quantitative x-ray diffraction could possibly revolutionize forensic soil examination. When developed to the point that this or similar methods become routine laboratory techniques, it will be possible to do a quantitative mineralogical analysis that is easily reproducible. However, the microscope will remain an important tool in the search for the unusual grain or artifact.  Sampling methods, plus the thorough and complete training those people who collect samples for forensic purposes, will be improved.   Soils are extremely sensitive to change over short distances, both horizontally and vertically.  Soil sampling in many cases is the search for a sample that matches.  The collection of all the other samples serves only the purpose of demonstrating the range of local differences.  In collecting soil samples for comparison, we are searching for one that would have the possibility of matching.  Screening techniques applied during sampling that eliminate samples that are totally different are often appropriate.  For example, a surface sample offers little possibility of matching with material collected at a depth of four feet in a grave.

Studies that demonstrate the diversity of soils are important. One approach is to take an area that one would normally assume was fairly homogenous in its soil character and collect a hundred samples on a grid.  Each pair of samples would then be compared with each other until all the pairs are shown to be different.  Starting with colour and moving on to size distribution and mineralogy, different methods are used to eliminate all of these pairs as appearing similar. Junger (1996) performed several such studies and suggested methods for soil examination.

The qualifications and competence of examiners are a very major problem.  How do you learn to do forensic soil examinations?  This requires a thorough knowledge of mineralogy and the ability to effectively use a microscope and the other techniques used in earth material examina­tion. It is also important that examiners be familiar with the other kinds of trace evidence plus the law and practice of forensic examination.


Junger, E. P.  1996.  Assessing the Unique Characteristics of Close-Proximity Soil Samples: Just How Useful is Soil Evidence?  Journal of Forensic Sciences,  41  27-34.

 McPhee, J.  1997.  Irons in the Fire. Farrar, Straus and Giroux, New York.

 Murray, R.C. and Tedrow, J.  1992.  Forensic Geology. Prentice Hall, Englewood Cliffs, N.J.               

Murray, R. C. 2004, Evidence from the Earth, Mountain Press, Missoula, MT

Presented at the International Conference on forensic Geology, London, 2003
















©  Copyright 2001 Ray Murray
This page was last modified Monday, February 01, 2010 .