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Unit 4 Assignment B - Analysing Forensic Evidence (Physical)
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Analysing Forensic EvidenceUnit 4
Assignment B
Within this assignment, analytical techniques undertaken by forensic scientists and their
reliability and accuracy will be discussed and evaluated based on evidence collected from a
mock crime scene. Analytical techniques are used to determine facts surrounding a crime,
and find out what actually happened. A variety of physical, biological and chemical evidence
is used to do this. This report will discuss two physical pieces of evidence from a crime
scene and justify why the method was used, as well as disadvantages and advantages of
the methods, and the validity of the results obtained.
Physical analysis
Physical analysis is useful as it allows examination of things such as footwear, leading to
gait analysis etc, and other things like using garments to examine fibres.
Footwear Analysis
Analysing footwear is effective in a criminal investigation and can lead to elimination of
suspects (if they don’t own the shoes that are seen to have been imprinted). Furthermore,
footprints can be found all over the scene, meaning they are highly accessible, they can be
found from anywhere like the scene of the crime to even on things such as the victims
clothes. However, there can be limitations of footwear analysis, whether the footprint is well
kept (it may have been swept away or rained in if the crime scene is outside for example)
can lead to it being hard to analyse, and they are not always a conclusive form of evidence,
and should be used in conjunction with other evidence.
● Photography: Usually within a crime scene, photography can be used to take initial
pictures and analysis of footwear - looking at things such as the impression the shoe
made, the pattern of the shoe, the size and the shape (if the physical shoe is also
present, a sketch can be drawn on an examination form - so further details can be
recorded as to how the shoe was handled and can be referred back to). It can also
be used to compare to other photos of potential footprints at the crime scene - to see
if one or more people are involved. It also allows the evidence to be preserved so it
can be analysed further into the case.
● Casting: Casting creates a replica of an impression of a footprint, this replica is 3
dimensional, therefore can be highly analysed as it creates a more detailed look at
the impression, casting works when you pour dental stone is mixed with water and
poured into the impression, and left to harden. However, if not done correctly, they
may break - and ruin the footprint altogether, and you must have the right
consistency. It can help making comparisons as well to other suspects footwear, but
it also requires more materials - so may be more costly and can also be harder to
use and easier to make mistakes, which could ruin vital evidence, so you have less
evidence to convict in court.
● Comparison Microscopes: These microscopes can make analysis easier - as it
allows for side by side comparison that a regular microscope does not. This means
you can put two objects of shoe impressions next to one another, and precisely
, compare marks, sizes and the treads on the shoes. However, comparison
microscopes can be costly - therefore, if an investigation doesn’t have a lot of budget,
this may not be readily accessible.
● As well as this, if it is a bloody footprint, the presumptive blood testing can enhance
these footprints, therefore, being able to make out any impressions better and
specific details.
Ballistics Analysis
Ballistics are a useful part of analysis within a crime scene investigation and analysis as you
can tell where the gun has come from (the serial number etc.) it can allow investigators to
work out which type of gun was used, as well as who used the gun.
Within guns, they have a cartridge case that can be left at the scene if ejected from the
barrel of a gun after it’s been fired. If this is the case, it is very useful as it can provide
information about what type of model the gun is, following, thus you can view the head
stamp, which can be another way to identify the model of the gun. On the head stamp, it can
include information such as calibre size, which you can then measure and compare to other
cartridge cases. As well as during firing, or when encased in the gun, rifling marks may be
seen on the bullet, rifling marks aim to provide the bullet with stability, and any types of
grooves are produced when the gun has been fired, and the bullet shot out, this can also
help with finding out the model of the gun. As well as this, micro stamping on the bullet
casing can help identify the manufacturer of a gun. It contains a unique serial number that
can be used to search for the original firearm.
Documents
When forensically analysing documents, multiple things can be done to analyse things such
as handwriting analysis, ink and paper analysis, and digital document analysis. This is
particularly helpful in things like fraud cases, or cases where a note has been left behind by
a suspect (say a ransom note), things such as the age of the document, the identity of the
author and the type of ink used can be discovered.
Within handwriting analysis, handwriting can be compared with other samples given by a
suspect, looking at how the words are written, as well as other things such as slanting of
words, pressure, spacing and the speed of which it was written, alongside this you can also
create a profile of how the offender may have been feeling - if they were in a rush or what
emotions they may have been feeling in the moment. An example of this would be that if
they have large writing, they have higher self esteem and tend to be more confident and
outgoing. Using this, you can develop a rough offender profile for your suspect. However a
limitation to this is that the evidence and offender profile created from this isn’t concrete,
other things such as analysis of footwear to determine stature and sex, should be used, as
they are preferable to handwriting analysis as it is not a scientific process. It is effective in
the way it can be used to determine cases involving signature authenticity or historical
documents.
Ink and paper analysis allows for the age of the paper and ink to be found, the origin and
what types were used on a document. It looks at chemical, physical and visual components
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