Forensic Examination of Soil

Raymond C. Murray, Ph.DLouis P. Solebello, MS

The purpose of this Chapter is to provide as much information as possible for forensic scientists involved in soil examination. It is our hope that this information will be usefull to geologists and soil scientists with limited forensics experience, as well as forensic scientists with little or no soils analysis experience. Our intent is to provide a foundation for forensic scientists interested in investigating the evidentiary value of soils in criminal and civil cases. This chapter should serve as a foundation for forensic scientists involved in evidentiary soils analysis. Many of the analytical methods that we discuss are not available to everyone. Each case, however, should be studied with the appropriate methods and assistance might be sought from other laboratories when more sophisticated methods are indicated.

The forensic examination of soil and related material is receiving increased attention because of its value in the legal process and its role in recent high-visibility cases such as the kidnapping and murder of DEA agent Enrique Camerena, in which soil evidence was critical. In Camerena, the examiner went to great effort to seek out the original location of the rock samples found on agent Camerena’s body. Soil evidence is valuable because there is an almost unlimited number of soil varieties and soils change rapidly from place to place even over short distances. The discriminating power in soil examination lies in the number and and kinds of minerals available. Thus, the identification of the minerals present provides information of great value1,2. These identifications should be supplemented with other data using other methods of analysis.

The forensic examination of soil does not lend itself to use of a simple measurement or analytical procedure. Soils are complicated mixtures that cany vary greatly within short geographic distances. The analysis of soils, therefore, requires the attention of an individual trained and experienced in a multitude of disciplines who can use that training and experience to obtain information of the maximum forensic value. The analyst must have an inherent desire to ask and seek answers to questions on a case-by-case basis. Therefore, the forensic scientist must learn to analyze samples for pertinent information as it is related to the case at hand. The complexity of soil provides great opportunities for producing very useful evidence, however, there are few simple standard procedures applicable to all cases.

Forensic Science Handbook, Volume I Second Edition, Chapter 11, Page 616, 2000