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Introduction:

A corpse
with serious injures  left  lonely  
stretch  on rare area from the
city. A fire broke out at  a lawyer
office just one day  before the court. A
car accident leads to claims the life of 
whole family . All previous cases are 
probable a crime scene.

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By
establishing methodical examination for the previous incidents  , investigators should be systematic at crime
scene  while searching for physical
evidence which can arrest the penetrators. Also, this process must be bone with
care  in order to preserve the decisive
evidences from damages.

At the scene
 the first officer arrived  is responsible for  defining the scene or evaluating the scene,
establishing a systematic plan for   collecting evidence without  desiring them, secure  the scene that  is potential contain a critical evidence,
recording the scene and determining the involved people in the case and
packaging and submissions of  evidence to
forensic laboratories.

 

 

In this
report we are going to  provide related  information to crime scene investigation ::

-Crime scene
work

-Types of
physical evidence.

-Chain of
custody.

-Recording
crime scene.

-Crime scene
safety.

 

 

 

 

 

 

 

 

Crime
scene work

Crime scene
investigation is the meeting point of science , logic and law. It is a process
that include purposeful documentation of the 
conditions of the crime scene. 
Also, it include the collection of any physical evidence that could  explain what happened and who did it.

If we take a look at who is
presenting at crime scene?:

1.Police officers:

 The first who 
arrive at a crime scene. They arrest the perpetrator if  still around 
and call for an ambulance if necessary. They are responsible for
securing the scene so no evidence is destroyed.

2.CSI unit:

Who documents  in a detail everything in the crime scene and
collects any physical evidence.

3.Medical examiner:

They present in case of homicide
to determine a cause of death and not always present.

4.Detectives:

They interview witnesses and
conduct with the CSI unit. They investigate the crime rely on  witnesses and physical evidence. 5.

5.crime
scene technician:

A  highly trained professionals  who analyses the evidence  from a crime scene  and present findings basing on the
results  of their analyses. The common
works of the technician are:

 -Collect, process, and analyze
fingerprints

-Collect physical evidence 
such as weapons.

-draw crime scene sketches.

-determine  which items
should be collected at the crime scene

-List the evidence and prepare it for safely transpotation to the
crime lab

-Take
photos of the whole crime scene.

 

6.Specialists :

Including entomologists, forensic
scientists and forensic psychologists  to
analysis the evidences.

If
we talked in detail about  the duties of
forensic scientist :

Carrying  out 
laboratory examination and analyses submitted  by 
law  enforcement.-

-Serving   as  expert 
witness  in  a 
court  of  law.

-Carrying
out tests  using scientific
techniques  such  as 
infrared spectroscopy 
spectroscopy  mass
spectrometry  and  scanning 
electron  microscopy.

-Ensuring  all 
laboratory  protocol  and 
regulations  are  followed.

-In
putting  data  into 
computer  programs  and 
data base  Information.

-Preparing  written 
reports  .

– -Coordinating  
activities  related  to 
crime scene  collection
preservation  and  transportation.

-Serving  as  lesson between  the 
forensic  laboratory  and 
crime scene  Investigators.

-Developing  ,maintaining 
and updating  work  quality 
standards  and  operating 
procedures.

-Coordinating  work 
with  other  members 
of  forensic   term 
and  without side.

Forensic scientists usually perform
their work in forensic or crime laboratory . They are responsible for comparing
and interpreting the physical evidence that was brought  by crime scene investigators. In specific
circumstances, forensic scientists may present at the crime scene  when the techniques of  the collection or preservation of the
physical evidence are in question.

 

Types of crime scene:

crime scene is the surrounding area
where a crime has been committed. Such as forest, road, house or it could be
any place.  Crime  provide clues that help  in solving 
the crime which was committed.

crime
scene  can either be primary or
secondary. Primary scene is a scene where the actual  crime took place. For example , in a murder
Investigation , the primary scene would be the place where the murder occurred
and the reason’s life was taken. In addition,
there might be additional crime scenes involved as well and it would be the
secondary crime scene. For instance , the criminal may have changed the place
of the body after the murder. Let’s say the body was removed and placed in  a forest then it would be the secondary crime
scene. Secondary crime scene can help in finding more evidence which help in
solving the case.

 

Scientific
method to a crime scene investigator: 

The successful certainly
observations that the investigators found can be determine by the obtained
results of the crime scene. The CSI should be methodical, reasonable and should
understand:

What
are the physical evidences at the crime scene?
The
procedure to protect and collect these evidences.
The
approach of how to obtain observations from these evidences.
 linking all the obtained results.

 

 

 

 

 

 

 

Type
of evidences:

Class
versus individual features :

The investigator of the crime scene
should have the ability to differentiate between the class features of physical
evidences and the individual.  It is not
possible to identify all the physical evidences by only linking them to a
related item or person. Therefore,  the
crime sense investigator (CSI) have the responsibility to discuss all the
results of his forensic analysis with the scientist of the crime laboratory
(lead detective) to find a cohesive and objective presentation of the evidence.
Furthermore, biological or physical evidences can be included in the class or
individual features and sometime exclude persons from the investigate
procedure.

Class
characteristics:

It is not necessary  that the physical evidence is related to a
common origin with a high degree of certainty, hence, only a group of sources
can only be located into a class and not a single. For the differentiation
between the class evidences, it is not always possible for the investigator to
find the exact or estimated probability values. A good example of class
evidence is  the polyester fibers.
Investigation will collect information concerning the makeup polyester  fiber, but it is not possible to state
affirmatively that the fibers came from a specific rug.  In addition, significance can be included to
the place and amount of the fibers regarding the murdered, suspicious and/or
crime scene. However, the investigators cannot accurately suggest that a specific
rug was the source of the fibers. 

Individual
characteristics:

Individual characteristics are
generally considered as measurable differences evidences( physical and
biological) which permits it to be related to a single source with a high level
of accurately. This allows the investigators to identify the uniqueness of any
single item of evidence. The mathematical likelihood which there are 2 matching
sources of the distinct evidence of individual is beyond human understanding .
The forensic examiner can illustrate in the court the scientific outcome which
excludes the probability of two identical sources of evidences (biological or
physiological) .

 

 

 

Direct
evidences:

 

Direct evidence means that no need
of further investigation due to an established fact. A good example for the
direct evidence is a recorded video of theft shop where the victim’s face is
clear and easy to be identified or the permit of the eyewitness who was in the
shop at the time of the shop robbery. Therefore, direct evidence does not
need  inference or hypothesis. It depends
to the knowledge or perception of the investigator and then directly confirm or
disconfirm the disputed fact.  

Circumstantial
evidence:

Circumstantial evidences are the
most evidences that are examined in the forensic laboratory, and it is depends
to the forensic scientist to illustrate an inference of his analysis to provide
the fact. Therefore, this type of evidence is relies on reasoning and not
direct inference of a fact. To conclude, Circumstantial evidence is when the
knowledge can be inferred from witness at trail. 

 

 Chain of custody:

At the crime place, all the
information of the crime scene includes individuals, action, permit, and the
investigation documents an important link in the chain of custody.  Chain of custody is a formal paper in order to
preserve the physical evidences. Starting with the arrival of the investigators
and the emergency people at the location of the crime scene, different
activities are scrutinized by hundreds of people with different roles in order
to ensure that the justice is achieved.

The protective procedures must be
done immediately at the place of the crime scene in order to protect all the
evidences. Then, the access to the crime scene should be controlled and the
investigation procedure  begun.

The chain of the custody illustrates
the transformation of the  physical
evidences from the place of the crime scene until the investigator releases the
crime scene ……..of the disposal of the evidence.

 

 

                                                                                        

Evidence submitted:
To lab for analysis.

Evidence received:
By property/evidence unit

Evidence collected:
At the scene by CSI; entered on log and secures.

                                                                    

Evidence returned:
To properly/evidence unit for storage

 

 

 

 

 

 

 

                                                           

 

Evidence released:
To CSI for court presentation

Evidence returned:
To property/evidence unit to await disposal

Evidence may:
Be returned to owner or destroyed (court determination

scheme 1: chain of custody
flowchart.

 

 

 

 

 

 

 

 

 

 

 

Figure 1: shows chain of custody.

 

 

 

 

 

 

 

 

 

 

 

Searching
for evidences:

Crime scene technicians  are in charge of  providing a systematic strategy for  Searching for physical evidences  in order to preserve them from contamination
and damages and to cover up all types of evidences. Therefore  for each type of area there is a unique
pattern should be followed   to achieve
the target.

The patterns the used in crime scene
investigations are:

-Spiral search
method: all most this method applies for
large areas which contains  tiny
individuals  in search.

-Grind search method: it is  also used   for
large areas that contains a abundant number of searchers. Also,  it is often used in open and woodland areas.

-Line search method: this
pattern used in moderate area with a few number of searchers.  

-Quadrant
search method: this method used for small areas.

Figure 5: shows search patterns

 

Recording
crime scene:

Recording is  one of the critical and significant  procedures 
in crime scene investigations  for
many reasons. It is important  since it
can help investigators to gain a comprehensive overview  and inclusive knowledge about crime scene.
For instance, it can provides  a
reliable  material evidence according to
their  position and inter-relation  to scene as well as, it can provides
witnesses with ability to indicate the position of people and things within
scene and time of crime .  finally, it
can support the court restricting the scene in details  with potential evidence as well as refreshing
memory of assessor  of any incident.

Recording crime scene can be done
by  photographs, notes and plans.

 

 

Photography:

Photography  is one of the most significant methods that
used for recording crime scene   due to its ability to provides a virtual
reality   picture for an incident.
Although,  it can be useless or excluded  by the court 
in case that  is taken after any change
made at the scene  therefore, the most
requirement for photography is the crime scene should be in unaltered
condition.

Photographs should include:

-Primary crime scene  and the adjacent area of area that incident
occurs.

-All objects at the scene  which can be used in investigation.

-All 
walls within the  place that crime
taken place and walls of  adjacent place.

-Weapons used , surface under corps
and blood stains.

-The relative position of objects as
well as body with adjacent  items in the
scene.

 

 

 

 

 

 

 

 

Figure2: recording crime scene by photography.

 

 

 

Notes:

 
the purpose of writing notes is to provide an inclusive and certain  records about observations ,  sequence of events and examination  of crime scene. Notes which written at the
time of incident may be it is not at logical 
sequence but that producible and can be fixed later on  be reorganizing sequences in report. In
addition, notes of events and 
observations maybe become non-significant or meaningful if it is written
without indicating to some important details which is in relation with incident
such as ( when, where, by whom , how…) 
therefore,  notes should include:

Time
and date that investigators arrived.
First
person arrived at crime scene.
Officer
who was in charge about this case.
Conditions
of weather.
The
is the  incident and what was
happening .
People
and activities taken place.

Investigators are in charge of
Preserving evidence therefore, they 
shroud concern about their movement 
pathway  while writing notes at
crime scene in  order to  keep evidence without damages and
contaminations.

Plans:

Plans are complement  details of notes and photographs as well
as  it provides specific details about
dimension  and an overview  for scene by showing scales and the exact
position of items that related  to the
scene.  There are several methods used to
plans crime scene, Floor –plan is one way of 
planning  both outdoor and indoor
crime scene which illustrate  the
location looking down from above. For instance, cross-projection or exploded
view  is very close to floor-plans but it
vary  in walls that folded to uncover
items that founded in the walls. Isometric projection sketches also used to
indicate items of physical evidence like bloodstains. 3D or tree-dimensional
sketches are new methods used in crime scene investigations which gives a
virtual  reality picture for the
scene.    

 

 

However the most common plans used
for crime scene investigation:

Sketch
plan ( rough sketch) :

Sketch
plan that drown at crime scene by investigators in order to show the position
of items and their relations with another items.

Sketch
plan contains:

-structure
or appearance of items in sketches by indicating each item by a number or a
letter and provides a ligand for items.

-sketch
should include time, date, and description of the crime.

 

 

 

 

 

 

 

 

Figures3; shows rough sketches.

 

 

 

 

 

 

Scale
plan (fished sketch):

Scale plans sketches with accurate dimensional  size, shape 
and position .it considers more accurate an sketch plan since it is
concern about artistically  view  or appearance, accuracy  and it is drown with scales.

 

 

Figure4: shows fished sketches.

 

 

 

 

 

 

 

 

 

 

 

Collection of evidence

Crime scene investigation depend on the collection and the analysis
of different type of evidence. There are physical and biological evidences. The
physical evidence is any nonliving items and the biological evidence refer to
any living being. Also, there is another important type of evidence called
impression. Impression is a patterns of the items when it contact with soft
surfaces like shoes patterns. The collection of impression which found in crime
scene is very helpful and important to the investigation. According to Locard’s
Exchange principle  that perpetrator when
enter a room he must leave something during contact with object or victim, and
at the same time he must take something with him.

 

 

 There are many different
types of evidence that can be collected from the crime scene such as :

biological
evidence

including blood
, hair ,body fluids and many other tissues.

Blood should be
collected in clean gauze pad or clean sterile cotton and allow to dry at room
temperature. Also, it should be 
refrigerated and frozen  and send
to laboratory as soon as possible. If there is dried blood on clothing, first
wrap the item in clean paper then place it in brown paper bag, seal and
label  the container and never try to
remove the stains from the clothes.

Hair can
adhered to a piece of film and sealed with polythene bag.

Figure  5:collect blood sample by clean sterile
cotton.

Latent print

Including palm print, fingerprint and footprint.

The collection of impression evidence need forensic specialist and
can’t just packed directly because it can be easily destroyed.

Fingerprint is the most important evidence which gives direct individual
information because no one have the same fingerprint even the identical twins. Dusting 
fingerprints with special chemicals is a way to collect latent print.

Figure 6:collection fingerprint by
black powder.

Trace evidence

Including fibers, glass fragments and soil.

Wrap the glass and fibers separately in clean paper( envelopes)
with lapels and send it to the laboratory for test.

Digital evidence

Including cell phone records , emails and internet logs.

Electronic devises , charges , cables and manual should be
collected. Also, cell phones, thumb drives and hard drives should be collected
and examined by different tools and techniques in specialized lab.

Drug evidence

Drug collection is based on the type of the drug. For instance,
plant should not be packed in plastic because of the moisture and mold growth.
And if the drug is in syringes or other sharp object it should be packed hard
sided packaging like cardboard cartons or glass vials then labeled the
biohazards.

Figure 7: use glass tubes to
collect drugs.

Firearm evidence

-Never send a loaded gun to the laboratory unless it’s taken in
person. Also, firearm should never be shipped even if it is not cocked or on
safety. 

-never shot from the gun before it is being examined  in the lab. What is more,  the firearm should not be cleaned the bore ,
cylinder or chamber before submitting

– do not place
pencil or any object in the end of the barrel when pick up a firearm.
– record the caliber ,model ,make and serial number of the firearm.
– firearm should be packed and place in strong wooden box or cardboard to make
sure that the weapons will not shift during the transition.
– gunshot and rifles should not be taken separately.

Figure 8: gun collected in plastic
bag.

 

crime scene safety:

This may refer to the procedures
followed to control crimes there must be proper equipment to process the scene
depending on the situation to protect the body. The scene has to be secured and
protected before you process it ,this is for the safety of the crime scene
officers and everyone else. The first one is to put on latex gloves which are
important for protecting evidence because they keep you from leaving finger
prints behind. They offer you protection from blood and other substances at the
scene so remember to cover your shoes or boots with rubber boots when you are
indoors. Photograph the shoes of everyone at the scene including the officers
and the technicians, so that you can distinguish their imprints from those of
suspects. Pay attention to the types of shoes or boots you wear they must have
a good attraction and ankle support and will offer you protection from hazards
such as nails. A helmet is also important they light and easy to store and eye
protection there might be chemicals processed depending on the situation.

Figure 9: wear latex gloves to
protect you from dlood contaminations , diseases and protect you from bieng
suspecious by lnot leaving your fingerprint.

 

Personal
protective equipment:

Personal protective equipment (PPE)
at the crime scene  is very important for
the crime scene investigator and they should take it into consideration in
order to protect themselves from any hazards that may occur at the
investigation place. PPE may include wearing gloves, shoe covers, full body
suits and safety glasses. The first responders at the crime scene should
immediately ensure that there is no threats to the investigators in the crime
scene. Therefore, preventive measure must be followed in order to reduce the
threat of any accidental contamination. 

 

Conclusion

This report gives important information about crime scene
investigation. The persons who present in crime scene and their exact jobs.
Moreover, the different types of crime scene (primary and secondary). Also, it
shows information about the important procedures before starting the
investigation such as approaching , medical assistant and crime scene securing.
In addition, it gives all the important information about the  whole investigation procedures and the crime
scene safety.

 

References:

Books:

.The Practice of Crime Scene Investigation ,
by John Horswell.

.Techniques of Crime scene Investigation,
Eighth Edition , by Barry A.J Fifher,daived R. Flasher. 

.Crime Scene Investigation, by Jacquelline
T. Fifh,Larry S. Michael C. Braswell, Edward W Wallace.

Websites:

-Layton,
Julia. “How Crime Scene Investigation Works.” HowStuffWorks Science,
HowStuffWorks, 2 Dec. 2005, science.howstuffworks.com/csi.htm.

-“CSI Job Description.” How to
Become a Crime Scene Investigator, www.crimesceneinvestigatoredu.org/job-description/.

-“How
to Become a Crime Scene Technician: Career and Salary Information.” Criminal
Justice Degree Schools, 

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