In order toproperly understand how Forensic Soil Analysis is performed one must understandwhat soil is. Soil is a layer of earth in which plants grow, ablack or dark brown material typically consisting of a mixture of organicremains, clay, and rock particles (oxforddictionaries.com, 2017). Scientistsdescribe soil as being made up of differently sized particles like sand, salt,and clay (Tibbett, M., & Carter, D. O. 2008).
Soil contains a complexbiological, chemical, physical, and mineralogical properties that always changeas time goes on (Tibbett, M., & Carter, D. O. 2008). Forensic Soil Analysisuses soil sciences and other disciplines to aid in a criminal investigation(crime museum, 2017).
Soil in a way resembles fingerprints because of the factthat each sort of soil that exists has distinguished properties that are likeidentification marks (crime museum, 2017). This implies the origins of the dirtcan be recognized or identified to link to crime scenes (crime museum, 2017).For instance, mud stuck under a tennis shoe of a criminal can be followed backto a particular mud found along an area where a murder casualty was found(crime museum, 2017). The largest part of soil cases includes impressions fromfootprints or tire tracks that have been left in the dirt of crime scenes (crimemuseum, 2017). Asstated before soil has many different properties that make them unique intonarrowing down variables in a crime scene. The three main unique properties of soil are as follows: Sediment,which is the original solid particles that could be in the form of a grain ofrock that breaks off of the larger parent material (crime museum, 2017).Soils can develop on these sediments due to physical and chemical alteration (crimemuseum, 2017).Color, which indicates its historyas well as the compounds present in the soil (crime museum, 2017).
Structure,which indicates whether a soil is composed of a single grain particle or not.This is determined by the presence of clumps that are formed due to cementingagents such as calcium carbonate attracting the soil particles so that theyadhere to each other (crime museum, 2017).Over time criminals havebecome smart and well-aware that they need to hide and cover their trails like fingerprints whencommitting a crime (study.com, 2017). Some are even adept at trying to destroyDNA evidence from a crime scene (study.com, 2017). But rarely does the newsreport that soil-based evidence was destroyed or pre-empted by a criminal(study.com, 2017).
Most likely because not long ago, no one, not even lawenforcement, thought much of using soil as a means of criminal investigations(study.com, 2017). But now forensic soil analysis and evidence can help findbodies, disprove alibis, and help figure out where an important piece ofevidence came from (study.com, 2017).The way soil is collected, preserved, and tested is one of themain contributions Forensic soil analysis brings to the success of crime labsin the field (study.com, 2017).
Before any soil can be tested oranalyzed it must first be collected, and then properly contained forpreservation for later analysis (study.com, 2017).Criminal investigators will collect control samples, which are samples of soil, rock, or sediment thatare taken at a known date, time, and location (study.com, 2017).
Such control samples are then compared to questioned soil samples, soil found on objects of interest, likeshoes or tools (study.com, 2017). Soilsamples are collected in different ways depending on where it is beingcollected from (crime museum, 2017). If samples arebeing collected indoors or from a vehicle vacuuming is generally used (crimemuseum, 2017). If the sample is outdoors it’s collected byplacing a teaspoon of soil into a plastic vial (crime museum, 2017). When found on a tool, it is wrapped in plastic and thensent to the lab for testing (crime museum, 2017). When soil samples are collected off of a it takes more workand care so that the evidence doesn’t get contaminated (crime museum,2017).
When collecting samples from a body, samplesshould be taken at regular intervals and a different spoon should be used eachtime (crime museum, 2017).The collected control samples should beplaced into rigid, airtight and watertight plastic containers (study.com, 2017). Paper bags and polythenebags are not always adequate when storing soil evidence due to risk ofpunctures and tears in some kinds of samples (study.com, 2017). Metal containers add contaminants to samplesand should are avoided when obtaining soil (study.
com, 2017). Glass jars can be used in some cases where somesoil samples may react with plastic, but normally their usage is avoided sincethey may break (study.com, 2017).When glass jars used the lids on them would be lined with non-reactive material(study.com, 2017). All CriminalInvestigators/Forensic Soil Analyst label in the field using pre-determinedcode by taking supporting information such as photographs of the samplinglocation, as well as notes about the location and condition of recovery (study.com, 2017). Once soil samples are obtained they’ll be sent tothe laboratory.
At the laboratory samples are separated by the victim and thesuspect (crime museum, 2017). To examine the samples an examiner uses amicroscopic analysis to do testing on the mineral content. Another test thatanalyst do to identify the origin of soil is a density test. The density testconsists of adding liquid to two glass tubes (crime museum, 2017).
The liquid in both tubes is the same, but the rations are different (crimemuseum, 2017). This represents two different densities (crimemuseum, 2017). The soil sample is added to both liquid samples (crimemuseum, 2017). When the soil samples are suspended in the liquid the separationof the bands are analyzed to reveal the contents of the soil (crimemuseum, 2017).
Heat tests are also used to test soil reaction andelectron microscopes can be used to examine the structure of the minerals inthe soil (crime museum, 2017). During examination, an examiner will find thatsome soil samples contain biological evidence such as saliva, semen or blood (crimemuseum, 2017). If biological evidence is found in the sample thewhole soil sample is sent to the laboratory for further testing (crimemuseum, 2017). In conclusion the foundations of Forensic Science reachesback hundreds of years, and history records various cases in which peoplefirmly observed evidence and connected basic scientific principles to solvecrimes. With the steady advance of forensic science technologies duringthe twentieth century various fields Soil Analysis have impacted the CriminalJustice system in a positive to way to aid in suspect apprehension. ForensicSoil Analysis may not be the center ofboth forensic investigation of ongoing criminal cases and research but, newtechniques are being discovered every day to aid investigators in the future.
