CSI vs. “CSI”1. How is real CSI similar to TV CSI?

2. How is real CSI different from TV CSI?

3. Does real CSI typically handle an entire case from start to finish?

List a few things from CSI that are possible and not possible from your own opinion.

Possible Not Possible

Unit 2 – Crime Scene Investigation and

Evidence Collection

• How is it possible to identify the person who committed a crime?

Crime Scene Investigation:

• Defined: the goal of a crime scene investigation is to recognize, document, and collect evidence at the scene of a crime. Solving the crime will then depend on the piecing together the evidence to form a picture of what happened at the crime scene.

Principle of ExchangePrinciple of Exchange Established by Dr. Edmond Locard,

the LOCARD PRINCIPLE states:• When a person comes in contact with an object or another person, a

cross-transfer of physical material can occur • Studying the material can determine the nature and duration of the transfer• To a forensic examiner, these materials that are cross transferred

constitute what is called trace of evidence. • What are some Examples????

A Few Examples Include

• Pet hair on your clothes or rug• Hair fibers on clothing• Fingerprints on glass • Soil tracked into your house on your shoes• A drop of blood on a T-shirt • A used facial tissue • Paint transfer from a car to bicycle• Broken glass• and much more.

Hair Fibers

Fibers

Automobile Paint Chips

Soil Sample

Polymers

Footprint

Ted Bundy’s Bite Marks

Ted Bundy’s Head after the Electric Chair

Interesting Side Note!

Types of Evidence Types of Evidence

Types of Evidence

• Direct Evidence: includes first hand observations such as eyewitness account or police dashboard video cameras.

• Example: Eyewitness, Photos, Video Tape

Eyewitnesses• Question:

– Should eyewitness testimony be enough to make a conviction in a criminal case?

• Why or Why Not

•Don't always trust television!.. Crime shows love to show the compelling "eyewitness" testimony.  Most laypeople believe that an eyewitness is the cornerstone of a criminal case.  However, police officers and courts  rarely use eyewitnesses.  Why?  Because the human mind can only focus on one or two things at at any one time.

• Circumstantial Evidence: is indirect evidence that can be used to imply a fact but that does not directly prove it. No one, other than the suspect and victim, actually sees when circumstantial evidence is left at the crime scene. This evidence can be physical or biological in nature.

• Example: finding a gun at the suspect’s house, bloody knife, fingerprints, etc.

Trace Evidence

• Trace evidence is a type of circumstantial evidence.

• Examples:– Animal or Human Hair– Fingerprints– Soil of Plant Material (Pollen)– Body Fluids (Mucus, semen, saliva, or blood)– Fiber or debris from clothing– Paint Chips, broken glass, chemicals

Types of Circumstantial Evidence

• Physical: Evidence not from living organisms

Examples: impressions such as fingerprints, footprints, shoe prints, tire impressions, and tool marks, gun, knife, car(not paint), pan.

Biological: From living organisms

Examples: body fluids, hair, plant parts, and natural fibers.

Explain why this would or

would not be trace evidence.

2 Classifications of Evidence• Class Evidence: narrows an identity to a

group of persons or things. Knowing the ABO blood type of a sample of blood type that may have been there, excludes others.

• Individual Evidence: narrows an identity to a single person or thing. Individual evidence typically has such a unique combination of characteristics that it could only belong to one person or thing, such as a fingerprint.

Do Now:

• On a separate sheet of paper to hand inDefine and list an example of each.

1. Direct Evidence

2. Biological Evidence

3. Physical Evidence

4. Class Evidence

5. Individual Evidence

•Who is involved in a crime-scene investigation?

• Police Officers: are usually the first ones to arrive.

• Crime-scene Investigators: document the crime scene in detail and collect physical evidence.

• Medical Examiners/Coroners: may be necessary to determine the cause of death.

• Detectives: look for leads to interview witnesses’.

• Specialists: insect biologists (entomologists), forensic psychologists, etc.

The S’s of Crime-Scene Investigation

The Seven The Seven SS’s of Crime Scene ’s of Crime Scene Investigation Investigation

1. Secure the scene2. Separate the witnesses3. Scan the scene4. Seeing the scene5. Sketch the scene 6. Search for evidence7. Secure the collected evidence

1. Securing the Scene

• First-responder: First officer at the scene– Responsible for safety to all the individuals

– Preservation of evidence.

– Must start a security log and collect any other important information

2. Separating The Witnesses

• Why do you think it is important to separate the

witnesses????

2. Separating The WitnessesWitnesses should not be allowed to talk to eachother because their accounts will be compared.

Questions to be asked:• When did the crime occur?• Who called in the crime?• Who is the victim?• Can the perpetrator be identified?• What did you see happen?• Where were you when you observed the crime

scene?

3. Scanning The Scene• Forensic examiners need to scan the scene

to determine where photos should be taken. A determination may be made of a primary crime-scene and secondary crime scene.

• Write your own example of a primary and secondary crime scene

• Example: Where robbery took place is primary and where the suspect lives is the secondary crime-scene.

4. Seeing The Scene

• A view of the crime scene should be taken from several different angles and distances. Several close-up photos of any evidence and bodies should be taken.

Wide angle lenses are used to distort the truth or emphasis it

Details preserved

5. Sketching The Scene

• An accurate rough sketch of the crime scene is made, noting the position of the body (if any) and any other evidence. All objects should be measured from two immovable landmarks.

Blank Crime-Sketch Form

Nirvana

6. Searching for Evidence

• These patterns are systematic, ensuring that no area is left unsearched.– Grid– Linear– Quadrant or Zone– Spiral

Crime-Scene Search Patterns

7. Securing and Collecting Evidence• All evidence needs to be properly packaged,

sealed, and labeled. Specific procedures and techniques for evidence collection and storage must be followed. An evidence log and a chain of custody document must be attached to the evidence container. The evidence log should contain all pertinent information, including:

• Case number, item inventory number, description of the evidence, name of suspect, name of victim, date and time of recovery, signature of person recovering the evidence, signature of any witnesses present during collection.

Blood Spatter Analysis

Cast’s of Physical Evidence

Packaging Evidence

1. Crease a clean paper and place evidence in the X position

2. Fold in the left and right sides, and then fold in the top and bottom

3. Put the bindle into a plastic or paper evidence bag affixing a seal over the opening

4. Write your name on the seal

Paper Bindle Folds

Evidence ID Forms

Evidence Bag

Maintaining a chain of custody log is essential to present credible evidence in court

What determines the type and manner of collecting and preserving physical evidence?

• The nature of the evidence

Q. What type of evidence is to be retrieved from a deceased victim for examination in the crime laboratory?

• Clothing

• Fingernail scrapings

• Head and pubic hairs

• “Orifice” swabs

• Bullets

• Hand swabs for gunshot residues

Chain of Custody

1. -Bag the evidence-Add identification -Seal it-Sign it across the sealed edge

2. -Sign over to a lab technician -Open bag on non-sealed edge

3. -Return items to the evidence bag-Seal evidence bag in another bag-Sign the evidence log

Forensic Science: Fundamentals & Investigations, Chapter 2

Analyze the EvidenceAnalyze the Evidence

• Facts result from collected evidence processed by the forensic lab

• Lead detectives aim to see how facts fit into the crime scenario

Analyze the EvidenceAnalyze the Evidence

Lab results can:

• Show reliability of witness accounts

• Establish the identity of suspects or victims

• Show suspects to be innocent or link them with a scene or victim

Crime Scene Reconstruction Crime Scene Reconstruction

Crime scene reconstruction involves:

• Forming a hypothesis of the sequence of events

• From before the crime was committed through its commission

Staged Crime Scenes Staged Crime Scenes When lab results don’t match up with the

testimony of witnesses

Common examples:

• Staging a fire—to cover bankruptcy

• Staging a suicide—to cover a murder

• Staging a burglary—to collect insurance money

Staged Crime ScenesStaged Crime Scenes

Was the crime scene staged? Consider:

• Does the type of wound match the weapon?

• Could the wound be easily self-inflicted?

• What were the mood and actions of the victim before the event?

• What were the mood and actions of the suspect before the event?

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

SummarySummary . . . . . . . . • Locard’s exchange principle: – Contact between people and objects can

transfer material that can determine the nature and duration of the transfer

• Evidence can be direct or indirect – Physical or biological traces

• A crime scene investigation team consists of police, detectives, crime scene investigators, medical investigators, and specialists.

• Investigations consist of recognizing, documenting, and collecting evidence.

• First responding officers identify the extent of the crime scene, secure it, and segregate witnesses.

• Crime scene investigators document the crime scene.

• Evidence is collected, packaged, and labeled.

• The evidence is analyzed and interpreted to fit the crime scenario.