This document discusses various aspects of processing a crime scene, including: - Crime scenes are classified based on factors like motive, location, and criminal behavior. - A thorough investigation of the crime scene is important for proving or disproving aspects of the case. - Various professionals like police officers, crime scene investigators, medical examiners, and detectives all play roles at a crime scene. - It is important to properly secure, document, collect, and preserve evidence found at the crime scene to avoid compromising the integrity of the evidence.

1. The Crime Scene
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2. Forensic labs DO NOT solve crimes
(they just analyze the evidence)
INVESTIGATORS SOLVE CRIMES
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3. Physical Evidence
• Encompasses any and all
objects that can establish
that a crime has been
committed
or
any and all objects that
can provide a link between
a crime and its victim or a
crime and its perpetrator.
Crime Scene
•It is the beginning point
for obtaining evidence
which will be used by the
crime scene investigator
and the forensic expert.
•A thorough investigation
of crime scene is must for
proving/disproving
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4. A Crime Scene
• Crime scenes are never consistent- they are
ALWAYS INCONSISTENT
– Each one presents an investigator with a new challenge
• That is why crime scenes are diversely classified based
on various factors
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5. Classification
Based on motive of
crime
• Homicide,
• Robbery,
• Sexual assault,
• Terror attack
Criminal behavior
associated with scene
•Passive
•Active
Mode of committing the
crime
•Organized crimes
•Dis/unorganized crimes
Physical location
•Indoor,
•Outside ,
•Vehicle
Geographical area
•Macroscopic
•Microscopic
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6. Who’s at Crime Scene..??
1. Police officers
2. CSI unit
3. District attorney
4. Medical examiner
5. Specialists
6. Detectives
Police Officers:
1. Usually 1st on the scene
2. Make the arrest, if possible
3. Call ambulance if needed
4. Secure the scene --- WHY?
CSI UNIT:
1. Secure the scene
2. Collection, preservation and dispatch of
samples.
3. Maintains the record.
MedicalExaminer:
1. May or may not be present to
determine a preliminary cause of
death.Specialists:
May be called in if evidence requires expert analysis-
Entomologists
Forensic scientists
Forensic psychologistsDetectives:
Interview witnesses and consult with the CSI unit
Investigate the crime by following leads provided by witnesses and
physical evidence

7. Objectives of CSI
• Using generally accepted
scientific methods, Locard’s
Exchange Principle, and
forensic techniques, CSI can
achieve –
– Recognition- scene survey,
documentation, collection
– Identification- comparison testing
– Individualization- evaluation and
interpretation
– Reconstruction- reporting and
presenting
Questions that can be
answered after CSI are-
•What happened..?
•Where did it happen...?
•When did it happen..?
•Why did it happen..?
•Who may have perpetrated
these actions..?
•How was the incident
carried out..?
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8. Processing the
Crime Scene
– Safety first
– Fulfill the basic legal
requirements
Secure and protect the scene
Record the scene
Locate and mark the evidences
Collect, pack, and label the
evidences
Dispatch exhibits and Submit report
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9. Securing The Crime Scene
• The first officer at the crime scene is responsible for
securing and protecting the area
– Must first make sure that if the victim is alive, medics are on
their way
– Must secure the area with crime scene tape or other barriers
– Must make sure that the evidence does not get
compromised
– Must make sure that witnesses do not leave the crime scene
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10. Recording The Crime Scene
• Has only a limited amount of time to work a crime scene
– Must photograph the crime scene
– Must sketch the crime scene
– Must take notes
– Must collect, document, label and package the evidences
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11. Photography; general rules
• The crime scene must not be altered before/during
photography.
– Objects must remain where they are until photographed
• Any proof that the crime scene was compromised would cause the
evidence to not be admissible in court
• If evidence has been removed or moved, it must be mentioned in the
report
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12. Photography; general rules
• Each crime scene needs to be photographed as
thoroughly as possible.
– All areas where the crime took place should be photographed at
different angles
– Entries and exits must also be photographed at different angles
– It is important to have close-up shots and far-away shots
– Evidence should be photographed with a ruler as a point of reference
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13. Sketches of Crime Scene
• Sketches of crime scene are made after photography.
• Types of sketches are-
– Rough- a draft representation of all essential info and
measurements at a crime scene
– Finished- a precise rendering of the crime scene
• All sketches are drawn to scale
• All sketches have a legend showing where certain items are at
the crime scene
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14. Sketches of Crime Scene
• Crime scene sketches must have-
– Title or caption
– Legend of abbreviations
– Symbols
– Numbers of letters used
– Compass designation
– Scale, if drawn to scale
– Documentation block with case number, offense type,
victim’s names, location, date and time, and
sketcher’s name
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17. Note Making of Crime Scene
• Throughout the crime scene processing time
• Should include-
– Date and time
– Arrival information
– Scene description
– Victim description
– CSI team members
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18. Notes making….
• Description of the scene
• Location of items of physical evidence recovered with
following details-
– Time when an evidence was discovered/located,
– By whom,
– How,
– By whom it was packaged and marked,
– The disposition of the item after it was collected
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19. Locard’s Principle
"Wherever he steps, wherever he touches, whatever he leaves, even
without consciousness, will serve as a silent witness against him his
fingerprints or his footprints, but his hair, the fibers from his clothes,
the glass he breaks, the tool mark he leaves, the paint he scratches, the
blood or semen he deposits or collects. All of these and more, bear
mute witness against him. This is evidence that does not forget. It is not
confused by the excitement of the moment.
It is not absent because human witnesses are. It is factual evidence.
Physical evidence cannot be wrong, it cannot perjure itself, it cannot
be wholly absent. Only human failure to find it, study and understand
it, can diminishits value.”
~Dr. Edmond Locard 1877–1966)
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20. Locating the Evidence
• Must be thorough and systematic
– Must make sure not to overlook any pertinent evidence
– Failure to do so can lead to accusations of negligence or of covering up the
evidence
• Field evidence technician responsible for conducting
search for evidence
– May also photograph the crime scene
– Looks for fingerprints, footprints, tool marks, hairs, fibers, etc
– Must also collect possible carriers of trace evidence
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21. How to Search for Evidence
• Crime scene is usually searched in segments.
• 4 types of search methods are-
• Spiral search method- Search starts at an outer point and
gradually moves toward the center OR starts at the center and
gradually moves outside
• Grid method- Crime scene divided into a grid and each grid
segment is searched
• Strip or line search- Crime scene divided into strips and each
strip is searched
• Quadrant or zone search- Crime scene divided into quadrants
and each quadrant is searched
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22. Spiral Pattern
Inward Spiral Search Outward Spiral Search
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23. Grid pattern
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24. Parallel search pattern
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26. Search for Evidence
• Evidence must also be collected from the body (if
victim died) by the medical examiner
– Evidence needed includes
• Victim’s clothing
• Fingernail scrapings
• Head and pubic hairs
• Blood
• Vaginal, anal, and oral swabs (sex crimes)
• Recovered bullets from the body
• Hand swabs from shooting victims
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27. Collecting and Packaging The
Evidences
• Must be handled carefully making sure that exhibit does
not get damaged
– If damaged or changed, evidence is not admissible in court
• Each item or similar items collected at different
locations must be placed in separate containers
– Prevents damage through contact and prevents cross- contamination
• Forceps and other similar tools should be used to pick
up small items
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28. Collecting and Packaging
Evidence
• Small items may be put in unbreakable plastic bottles with
pressure lids
– Suitable for hairs, glass fragments, fibers, and other small
or trace evidence
• Manila envelopes are also good containers for evidence
• Paper bags are excellent containers for large evidence
• Mailing envelopes should NEVER be used to hold evidence
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29. Collecting and Packaging
Evidence
• Any evidence that is wet must be air dried before
being placed in a container
• Bloodstained evidence should never be stored in
an air-tight container
– Could cause mold growth which damages the
evidence
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30. Collecting and Packaging
Evidence
• After evidence is collected and packaged, the
container it is in must be marked and sealed
• Most items should be packaged in a primary
container and then placed in a secondary container
– Hair is placed in a vial which is then placed
inside a paper bag
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31. Chain of Custody
• Is a list of all persons who come in possession of an item
of evidence
• Must be established whenever evidence is presented in
court
– The evidence container must be marked for identification
– The collector’s initials should be placed on the seal
– If evidence is turned over to another person, the transfer must
be recorded
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33. Obtaining Reference Samples
• A standard/reference point is physical evidence
whose origin is known, such as hair from a suspect
that can be compared to a hair found at the crime
scene
– Exists with blood, glass, soil, fibers, paint chips,
etc
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34. Medical Examiners
• Is a medical doctor, usually a pathologist
• Is authorized to conduct autopsy and to announce the
cause of death based on autopsy finding.
• Can be asked to give his expert testimony in courts.
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35. Responsibilities of the M.E.
• Identify the deceased
• Establish the time and date of death
• Determine a medical cause of death
– The injury or disease that resulted in the person
dying
– Examples
• Gunshot, stab wound, heart attack, cancer
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36. Responsibilities of the M.E.
• Classify the manner of death
– The circumstances in which the cause of death arose
– Is usually the most difficult to determine
– 5 types of manner
• Natural- death due to disease process
• Accidental- death by an act that one would expect to survive
• Suicide- intentional termination of one’s own life
• Homicide- death due to an intentional act by another individual
• Undetermined- death in which the manner and/or cause cannot
be determined
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37. Responsibilities of the M.E.
• Determine the mechanism of death
– The physiological or biochemical reason that the
person died
– Examples
• Coronary artery disease- heart attack
• Cerebral edema- head injuries
• Hemorrhage- stab wounds
• Notify the next of kin
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38. Crime Scene Safety
• Guidelines exist to protect investigators at crime
scenes
– Must wear latex gloves and shoe covers
– Must wear masks when potentially infectious dust or mist
is at the crime scene
– Must be alert to sharp objects
– Must maintain red biohazard bag for disposal of
contaminated materials
– Must not eat, smoke, or drink at the crime scene
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