Unit 23: Authorised Assignment Brief for Learning Aim A - Forensic Evidence, Collection and
Analysis
It is important to establish the purpose of criminal investigation:
• What – The investigators must know what the motive of committing the crime was. The
‘modus operandi’ (method of operation) is recorded because it helps law enforcement connect
different crimes regarding their similarities, helping to create a profile for the perpetrator.
• Who – The investigators need to know who the victim and who the perpetrator(s) were while
also finding any witnesses. If the victim is alive, the victim may be able to provide evidence
against the criminal; in addition, with witnesses' point of view.
• Where – The investigators must know where the crime took place and predict whether there
will be more targeted areas. In addition, investigators must try to reduce or prevent extraneous
variables from contaminating, destroying or altering evidence linked to the scene.
• When – In order to understand the reason why the crime was committed, the investigators must
start at the beginning of it all. This may aid investigators in predicting future crimes attempted by
a perpetrator.
Search patterns: https://www.crime-scene-investigator.net/PDF/las-vegas-pd-csa1-study-
guide.pdf
Search patterns are used to analyse a crime scene in an organised format to ensure there are no
area of ground undiscovered and unseen. This is to make sure no evidence, crucial to the
investigation, isn’t missed.
Quadrant / Zone – The way this method is used is by splitting up the crime scene into smaller
sections and choosing another suitable search method to analyse the smaller zone. It is usually
used for scenes that are large or analyse a small area in an organised manner or are indoor areas
because of the structure and shape of buildings/ rooms or e.g., cars. After a time period, the
investigators move to another section of the zone and analyse the same area another investigator
analysed; almost like a clock moving its hands around.
,Lane – An individual or group of investigators walk at the same pace in the same direction
(parallel to eachother) to search for evidence. Typically used for finding larger objects in a large
outdoor area e.g., bodies in a forest.
Grid – Similar to a lane search but this covers much more of the area and allows different
perspectives for searching evidence on the same general path. This is because the search party
will revisit their previous location when changing from longitude to latitude and vice versa.
Typically used for individuals or pairs/trios but can also be suitable for large groups, depending
on the size of the area being searched.
Spiral – Starting from the centre of a crime scene and spiralling outwards until the end of the
scene is reached, can be reversed and start from the outside and work towards the centre. This is
effective because it is well organised for looking at evidence scattered around the centre of the
crime scene. Mathematically speaking, it can cover the entire area of the circle/scene.
, Wheel – Being in the centre of the crime scene and walking one direction and back the repeating
it for multiple directions such as north, north-east, south etc. This method would be used for e.g.,
collecting shrapnel from an explosive for identifying the make of the explosive to then find its
orgin and clearing any threatening items, however it is not often used in investigations.
Health and safety approaching an investigation:
First, a First Attending Officer will scan the scene for any potential threats and/or harm to other
authorised personnel. After the FAO confirms safety, authorised personnel enter wearing
personal protective equipment (PPE) at all times to prevent harm to themselves and/or prevent
contamination to evidence. Forms of PPE:
Gloves: Gloves are used to prevent fingerprints of investigators going on to evidence collected
by themselves thus leading to them being a suspect, protect them from harmful substances, sharp
objects etc.
Shoe print covers: These are used so no alternative prints from investigators are made to then
confuse the analysis process thus leading to them being a suspect.
Analysis
It is important to establish the purpose of criminal investigation:
• What – The investigators must know what the motive of committing the crime was. The
‘modus operandi’ (method of operation) is recorded because it helps law enforcement connect
different crimes regarding their similarities, helping to create a profile for the perpetrator.
• Who – The investigators need to know who the victim and who the perpetrator(s) were while
also finding any witnesses. If the victim is alive, the victim may be able to provide evidence
against the criminal; in addition, with witnesses' point of view.
• Where – The investigators must know where the crime took place and predict whether there
will be more targeted areas. In addition, investigators must try to reduce or prevent extraneous
variables from contaminating, destroying or altering evidence linked to the scene.
• When – In order to understand the reason why the crime was committed, the investigators must
start at the beginning of it all. This may aid investigators in predicting future crimes attempted by
a perpetrator.
Search patterns: https://www.crime-scene-investigator.net/PDF/las-vegas-pd-csa1-study-
guide.pdf
Search patterns are used to analyse a crime scene in an organised format to ensure there are no
area of ground undiscovered and unseen. This is to make sure no evidence, crucial to the
investigation, isn’t missed.
Quadrant / Zone – The way this method is used is by splitting up the crime scene into smaller
sections and choosing another suitable search method to analyse the smaller zone. It is usually
used for scenes that are large or analyse a small area in an organised manner or are indoor areas
because of the structure and shape of buildings/ rooms or e.g., cars. After a time period, the
investigators move to another section of the zone and analyse the same area another investigator
analysed; almost like a clock moving its hands around.
,Lane – An individual or group of investigators walk at the same pace in the same direction
(parallel to eachother) to search for evidence. Typically used for finding larger objects in a large
outdoor area e.g., bodies in a forest.
Grid – Similar to a lane search but this covers much more of the area and allows different
perspectives for searching evidence on the same general path. This is because the search party
will revisit their previous location when changing from longitude to latitude and vice versa.
Typically used for individuals or pairs/trios but can also be suitable for large groups, depending
on the size of the area being searched.
Spiral – Starting from the centre of a crime scene and spiralling outwards until the end of the
scene is reached, can be reversed and start from the outside and work towards the centre. This is
effective because it is well organised for looking at evidence scattered around the centre of the
crime scene. Mathematically speaking, it can cover the entire area of the circle/scene.
, Wheel – Being in the centre of the crime scene and walking one direction and back the repeating
it for multiple directions such as north, north-east, south etc. This method would be used for e.g.,
collecting shrapnel from an explosive for identifying the make of the explosive to then find its
orgin and clearing any threatening items, however it is not often used in investigations.
Health and safety approaching an investigation:
First, a First Attending Officer will scan the scene for any potential threats and/or harm to other
authorised personnel. After the FAO confirms safety, authorised personnel enter wearing
personal protective equipment (PPE) at all times to prevent harm to themselves and/or prevent
contamination to evidence. Forms of PPE:
Gloves: Gloves are used to prevent fingerprints of investigators going on to evidence collected
by themselves thus leading to them being a suspect, protect them from harmful substances, sharp
objects etc.
Shoe print covers: These are used so no alternative prints from investigators are made to then
confuse the analysis process thus leading to them being a suspect.
