The analysis of evidence

There are three different forms of evidence which can be obtained from an investigation; chemical, physical and biological. Each piece of evidence requires to be analysed a specific way in order to maximise the effectiveness of its use within court. Within the investigation I have been studying regarding Guy Paul Morin, only two forms of evidence, physical and biological. However there are many different forms of biological and physical evidence obtained. 

Depending upon the type of biological evidence, determines the analysis’s which needs to be carried out.  In the case that I have been studying (regarding Guy Paul Morin) hair fibres found in the car belonging to Morin were presumed to be of Christine Jessop. The examination which was conducted on the hair analysis firstly consists of determining the origin of the hair, this meaning examining the medulla, cortex and the cuticle. From analysing the three components that make up a hair strand, the analyst is able to determine if the hair fibre belongs to a human being or an animal. When analysing the cortex, the analyst can identify if the hair has been coloured recently and the original colour of the hair, thus potentially identifying the hair colour of the suspect. From this information they will then proceed to identify where the on the body the hair originated from whether it is the head, facial, eyebrow, axillary (underarm) or pubic region. In addition, if the hair was ripped out of the individual, a small piece of skin will have remained upon the root. From the small piece of skin cell, a DNA analysis can be carried out upon it to identify who the piece of hair belonged to. Therefore the law officials can potentially positively identify the suspect, if the victim ripped out fragments of the suspects’ hair whilst in contact with them.

A second form of biological evidence which may be obtained from a crime scene is blood.  A presumptive test known as Kastle Meyer will initially be carried out upon the substance. The purpose of the test is to react with the haemoglobin within blood, to certify whether or not the substance is blood, if the results of the test are positive the substance will turn a distinct pink colour. The substance would then be further analysed to extract DNA to associate the blood with the victim or a potential suspect. The blood would be collected by placing several drops of distilled water onto a swab to collect the substance, (the purpose of placing liquid onto the swab is to liquefy the substance further as the presumed blood may have dried up on the floor).

There are a variety of physical pieces of evidence which may be obtained from a crime scene all of which need to be analysed specifically. A common form of physical evidence which is obtained from a crime scene is a weapon. As weapon can typically be of any shape and size, but they still have a similar procedure of analysis. Firstly, measurements will be taken from the weapon to identify the diameter and length, so it can be compared to the wounds upon the victim. The weapon will be photographed to identify any original marks upon the weapon, and to show the images when presented within court. Furthermore, forms of biological analysis could be carried out upon the weapon if it contained any biological evidence, such as blood splatter, fingerprints etc.

A second form of physical evidence which may be obtained from a crime scene is footwear marks, imprints will be made of the mark at the scene whether it is a 2d or 3d mark. A 2d impression mark indicates the length and width of the mark, they can be found on surfaces such as on doors, counter tops or glass etc. A 3D impression mark can indicate the length, width and impression of the print, which are typically found outdoors, such as in dirt, sand, mud or snow. Once the impression of the print is made different characteristics will be analysed to identify the size of the show, identify if they have any specific wear marks, what the make of the shoe is. All the information they gain will potentially help direct their attention to a potential suspect.

A form of physical evidence which was obtained from the investigation of Paul Morin was witness statements. An witness statement is a formal document which records the information stated from the individual regarding the incident in question, of which is then signed by themselves. The statement will include what they saw, heard or felt on the day of the incident which may provide as evidence within the investigation. 
A witness statement can be analysed be cross-referencing it with other witnesses regarding the same incident, in order to identify any correspondents between the statements, in order to suspect further facts. Furthermore, the investigator involved within the investigation can call upon the individual who provided a witness statement in order to question them in further detail. 

Depending upon the type of chemical evidence acquired from the crime, requires a different form of analysis. Within the investigation I am studying there was no forms of chemical evidence obtained, therefore I am going to discuss potential forms of chemical evidence obtained. A piece of chemical evidence which may be obtained from the crime scene is a form of drugs. A presumptive test if first used to determine whether the substance found are drugs or not, the test is known as spot testing. Spot testing involves adding a drop of a chemical reagent to the unknown mixture within a well dish. If the substance that is in question is present a chemical reaction will occur which will be characterised by a unique colour change. Once the drug has tested positive for a presumptive test, it will be then placed within a mass spectrometry. Mass spectrometry will show the different compounds within a substance and their quantity, which will verify if the substance is illegal. The results can then be compared to a toxicology report of an individual to identify if it is that particular substance within the body.

A second form of chemical evidence that may be obtained from the crime scene is gunshot residue. A presumptive test would be carried out upon the powder found to identify if the substance is in fact gunshot residue. The test that is used is known as a diphenylamine test which tests for lead nitrates, if the substance tests positive for gunshot residue there will be an instantaneous colour change to blue. However false positives are liable of occurring when carrying out the test, as a result of fertilisers or photographic products, therefore the investigators would be given misleading information.  If the substance tested positive for gunshot residue it would be sent off to the laboratory for further analysis, to identifying the components which made up the substance in order to potentially identify the gun that was shot.