Forensic soils examination - Essay Example

forensics is the application of a broad spectrum of sciences to answer questions of interest to the legal system. This may be in relation to a crime or to a civil action. The use of the term "forensics" in place of "forensic science" could be considered incorrect; the term "forensic" is effectively a synonym for "legal" or "related to courts" (from Latin, it means "before the forum"). However, it is now so closely associated with the scientific field that many dictionaries include the meaning given here.

Criminalistics is the application of various sciences to answer questions relating to examination and comparison of biological evidence, trace evidence, impression evidence (such as fingerprints, shoeprints (shoe prints on soil also), and tire tracks) and other evidence in criminal investigations. A separate squad has been set up in US federal investigating agencies for this aspect of forensic research which play a vital role in leading to the culprit as he not immune from my commiting a blunder while carrying out his crime.

In real-life crimes, colour is one way that forensic scientists analyse soil from a crime scene or suspect. They can also check mineral composition, the density of the soil and its pollen content. The evidential value of soil stands on large variation in its characteristics.Soil has extreme complexity not only in components such as minerals, oxides, organic matter, micro organisms and their materials butalso physical nature such as particle sizes and densities. Considering the granite rock alone, for instance, there are an almost unlimited number of kinds.

They are easily recognized according to difference of color, mineralogy, texture and a lot of other characteristics. Diversity of soil is the results of many kind of formations process on diverse kind of parent materials, which strongly depends on topography, climate, course of years, botanical and microbiological functions, conditions of watering, and even human activities. Moreover, there are millions of fossils, external matters such as pollen and spores and even artificial materials. Forensic soils examination has been very complicated because of complexity of soil, but such diversity and complexity enables to discriminate soil samplers with high discriminating power.

The biggest problem in forensic soils examination is shortage of well-trained staffs and expertise for soils in crime laboratories. Especially mineralogical identification using polarized microscope requires sophisticated and experienced skill, and it also forces examiners to work patiently for many hours. Although considering complexity of soil a variety of methods have been proposed for many years, recent trend of reports has become simplification of procedures and methods. However, still standardization of forensic soil examination is difficult because of diversity of soil samples.

Methods sometimes must be changed to optimize for conditions of soil samples. Macroscopic observation and low-power stereomicroscopic observation is important at the initial step of forensic soil examination. It will be feasible for investigation if unique particles such as paint chips, fibers with distinctive color, glass fragments can be found both in a questioned soil sample and a control one. The examination can be focused on these unusual matters in soil, and at this step soil is only background to the evidence.

Forensic soil comparison stands on considerable variation among soil content. The significance of match between questioned samples and control ones must be interpreted in consideration of the intra-sample variation within questioned samples and control samples. As it is needed to demonstrate the range of local difference of soil for interpretation, the number of soil samples collected for comparison inevitably increase. Simple and rapid screening methods, therefore, are required for successful identification from a large number of soil samples.

Color comparison and determination of particle size distribution for soil samples can be carried out quite easily, and the combined data can be quite useful for discriminating among similar samples. We examine discriminating power of air-dried soil color and particle size distribution on soil samples, which had been collected systematically.Color comparison on air-dried soil alone is insufficient for discrimination of samples. In order to increase discriminating power it is required to study multiple color observation on soil samples.

This method composed of color observation on air-dried soil, moistened soil, the soil after decomposition of organic matter using hydrogen peroxide, the soil after removal of iron oxides using sodium Dithionite and the soil ignited at 850 C in an electric furnace. For the soil after decomposition of organic matter and after removal of iron oxides, finer particle fraction will be preferable color observation. Surface is dried deposit by centrifuging after these treatments, because it is more homogeneous than the bulk sample.

This procedure is done when colour seems to be the vital lifeline in a crime scene as in looking for a blood stain which then on processing matches with the suspect. Soil samples must be carefully collected, handled at the crime scene and then compared by a Soil Scientist to ensure that the soil samples can be useful during an investigation. To compare means to understand that no two objects on Earth are exactly the same; however, two soil samples (or other Earth material) could have originally come from the same place, but a portion of the soil (or other Earth material) could have been removed to another location during human activity.

Forensic Geologists look for uncommon and unusual particles or unusual combinations of particles, in soil samples and compare them with similar soil in a known location. Depending on the type of soil and the minerals present, in addition to grain size, the Forensic Geologist employs intensive observational methods and analyzes crime information to deduce whether a soil sample can be used as evidence.The Federal Bureau of Investigations (FBI) has collected and studied soil samples, minerals, and other Earth material for criminal investigations since 1935 and thousands of cases involving Earth materials are studied in the United States each year.

Throughout the world soil is usually collected at crime scenes, is routinely studied at crime labs, and is often used as physical evidence during crime trials. Microscopic fossils were once very prominent on Earth, and collectively deposited to form a sedimentary rock called diatomaceous earth. Some manufacturers use diatomaceous earth for insulating safes, which are used to store valuables. Burglary crimes have been solved by examining white specks from suspects' hair and clothing to determine that the specks were actually diatoms that came from broken safes at crime scenes, and not dandruff as the suspects had claimed.

References:www.wikipedia.org - forensic definition and information regarding soil analysis while the rest I knew as I learned it from a book during my early college years as it was part of my college syllabi.