Paint and Soil: Trace Evidence, Essay Example

Trace Evidence is part of Forensic Science Analysis in criminal investigations.  There are various types of trace evidence that forensic scientist examine, such as fire debris, glass, chemical substances, unknown substances, tire impressions, soil, and paint.  In addition, there are a multitude of technical instruments that are used in the analyses, such as scanning microscopes, Gas Chromatography/Mass Spectrometers, polarizing microscopes, and Glass Refractive Index Measuring Systems.  (New York State Police)  In this paper, the focus is soil and paint composition and its importance to investigators in forensic analyses for criminal investigations.

Paint can be an important part of a criminal investigation because it can be present on evidence from the crime scene and the techniques that are employed by Forensic Analysis’s are significant to criminal investigations. (Scottish Police Services Authority)  In addition, paint has a typical sequence in its laying composition, such as a basecoat, primer and topcoat.  Furthermore, in car accident investigations, the manufacturer usually has the same paint layer for that model of car.  The same goes for household items; there is usually a typical sequence, which provides scientists with clues to the investigation after analysis. Paint samples are then analyzed using instruments such as scanning electron microscopes which compare the sample to control samples in order to determine a match.   (Scottish Police Services Authority)

Soil is another factor used as trace evidence.  Soil is composed of earth material and can have different composition at different locations.  Soil samples allow investigators to determine where suspects or victims have been, whether taken from a body or object.  Collecting the soil sample at the scene of the crime depends on the location of the crime.  For instance, an indoor crime scene vs. an outdoor crime science will differ in that an indoor sampling method may require a vacuum method where the samples are vacuumed up; whereas, other methods from outdoor samples use plastic vials and usually one tablespoon of soil is sufficient as a sample.  In addition, reference samples are taken the same way.  For instance, in the case of a home invasion, a sample from a garden may be taken in order to compare soil from a suspects shoe vs. the garden from the house invaded.  The samples are taken to a laboratory where the soil can be analyzed in a variety of ways, such as microscopic examination, biological and chemical using methods such as Nuclear Resonencing and Mass Spectrometry.  These methods determine the content of the soil, match the soil to the victim, suspect and location, as well as confirm distances victim or suspect have traveled.  (Steck-Flynn, 2011 )

References

New York State Police. Trace Evidence. Web. Retrieved on September 7, 2012 from: http://troopers.ny.gov/Forensic_Science/Lab_Sections/Trace_Evidence/

Scottish Police Authority Services. Paint. Web. Retrieved on September 7, 2012 from: http://www.spsa-forensics.police.uk/services/chemistry/paint

Steck-Flynn, M.  2011. Analysis and Collection of Soil Samples. Web. Retrieved on September 7, 2012 from: http://www.crimeandclues.com/index.php/forensic-science-a-csi/trace-a-dna/20-analysis-and-collection-of-soil-samples