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Crime Scene Investigation

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Presentation on theme: "Crime Scene Investigation"— Presentation transcript:

1 Crime Scene Investigation
FORENSIC SCIENCE Crime Scene Investigation

2 INVESTIGATORS “The wise forensic investigator will always remember that he must bring all of his life experiences and logic to find the truth. This means common sense, informed intuition, and the courage to see things as they are. Then he must speak honestly about what it adds up to.” Dr. Henry Lee Chief Emeritus for Scientific Services and the former Commissioner of Public Safety for the state of Connecticut

3 First Officer at the Scene
A Assess the crime scene D Detain the witness A Arrest the perpetrator P Protect the crime scene T Take notes

4 Primary and Secondary Crime Scenes
Primary – where the crime actually takes place, for example, in a bank robbery the bank is the primary scene. The secondary scene is somehow related to the crime but is not where the actual crime took place, for example with the bank robbery, the get-away car and the thief’s hideout.

5 Once the Scene has Been Secured…
a lead investigator will start the process of evaluating the area. First the boundaries of the scene must be determined, then establish the perp’s path of entry and exit.

6 What will evidence collected at a scene do for the investigation?
Types of Evidence Testimonial evidence includes oral or written statements given to police as well as court testimony by people who witnessed an event. Physical evidence refers to any material items that would be present at the crime scene, on the victims, or found in a suspect’s possession. Trace evidence refers to physical evidence that is found in small but measurable amounts, such as strands of hair, fibers, or skin cells. What will evidence collected at a scene do for the investigation? May prove that a crime has been committed Establish key elements of a crime Link a suspect with a crime scene or a victim Establish the identity of a victim or suspect Corroborate verbal witness testimony Exonerate the innocent. Give detectives leads to work with in the case Source:

7 Adapted from
Crime Scene Protocol Step 1: Interview The first step in investigating a crime scene is to interview the first officer at the scene or the victim to determine what allegedly happened, what crime took place, and how was the crime committed. This information may not be factual information but it will give the investigators a place to start. Step 2: Examine The second step in the investigation of a crime scene, which will help identify possible evidence, identify the point of entry and point of exit, and outline the general layout of the crime scene. Step 3: Document The third step in the protocol involves creating a pictorial record of the scene as well as a rough sketch to demonstrate the layout of the crime scene and to identify the exact position of the deceased victim or other evidence within the crime scene. Step 4: Process This is the last step in the protocol. The crime scene technician will process the crime scene for evidence, both physical and testimonial evidence. It is the crime scene technicians responsibility to identify, evaluate and collect physical evidence from the crime scene for further analysis by a crime laboratory. Adapted from

8 Take photographs As soon as possible of the unaltered scene
Prior to moving or removing any evidence Close-ups of each item of evidence (use a scale)

9 Sketches are important because they relationships of items to other things They must be clear and show the coordinate position of each item of evidence

10 A rough sketch A finished sketch

11 Crime Scene Search Patterns
Spiral Search Grid Method Method Search pattern often extends out from key evidence or victim. Depends on area, Actions of suspects and victim.

12 More search Methods Strip, or line search, often used underwater or for very large areas.

13 1 more search method Quadrant, or zone search

14 Processing Physical Evidence
In order for evidence to be admissible, it must be: Legally obtained Probative—actually prove something (relevant) Identify the item Maintain the chain of possession Kendall/Hunt Publishing Company

15 Physical Evidence Transient Evidence--temporary; easily changed or lost; usually observed by the first officer at the scene Odor--putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smoke Temperature--of room, car hood, coffee, water in a bathtub; cadaver Imprints and indentations--footprints; teeth marks in perishable foods; tire marks on certain surfaces Markings

16 Physical Evidence (cont)
Pattern or Transfer Evidence--produced by direct contact between a person and an object or between two objects. There are several ways (at least 7) of classifying evidence. In this class, we will use: Biological Chemical Physical Miscellaneous

17 Biological Evidence Blood Semen Saliva Sweat/Tears Hair Bone Tissues
Urine Feces Animal Material Insects Bacterial/Fungal

18 Chemical Evidence Fibers Glass Soil Gunpowder Metal Mineral Narcotics
Drugs Paper Ink Cosmetics Paint Plastic Lubricants Fertilizer

19 Physical (impression)
Fingerprints Footprints Shoe prints Handwriting Firearms Printing Number restoration Tire marks Tool marks Typewriting

20 Miscellaneous Laundry marks Voice analysis Polygraph Photography
Stress evaluation Pyscholinguistic analysis Vehicle identification

21 Physical Evidence (cont)
Conditional Evidence--produced by a specific event or action; important in crime scene reconstruction and in determining the set of circumstances within a particular event. Light--headlight; lighting conditions Smoke--color, direction of travel, density, odor Fire--color and direction of the flames, speed of spread, temperature and condition of fire

22 Conditional Evidence (cont.)
Location--of injuries or wounds; of bloodstains; of the victims vehicle;of weapons or cartridge cases; of broken glass, etc. Vehicles--doors locked or unlocked, windows opened or closed; radio off or on (station); odometer mileage Body--position; types of wounds; rigor, livor and algor mortis Scene--condition of furniture, doors and windows; any disturbance or signs of a struggle.

23 THE BODY Rigor Mortis Temperature Stiffness Time Since
of body of body Death Warm Cold Not stiff Stiff Not dead more than 3 hrs Dead between 3 and 8 hrs Dead 8 to 36 hours Dead more than 36 hours

24 THE BODY Livor Mortis Livor mortis is the settling of the blood, causing the skin to change colors. Lividity indicates the position of the body after death. When lividity becomes fixed, then the distribution of the lividity pattern will not change even if the body’s position is altered. Lividity usually becomes fixed between 10 and 15 hours after death.

25 THE BODY Algor Mortis Algor mortis is body temperature. At a crime scene, it can be obtained in two different ways. Rectal temperature Liver temperature

26 Time Frame of Death Condition Appearance
Periphery blood drying 30 min to 2 hrs Blue-green discoloration of skin Right and left area of abdomen 24 hours Entire abdomen 36 hours Bloating to 48 hours Skin slippage 4 to7 days Absence of smell from bones more than 1 year

27 Time Frame of Death Eyeball Changes
Condition Appearance Cornea drying (eyes open) minutes Cornea drying (eyes closed) 2 hours Corneal cloudiness (eyes open) less than 2 hours Corneal cloudiness (eyes closed) 12 to 24 hours Eyeball collapse more than 24 hrs

28 THEREFORE, One can die of a massive hemorrhage (the mechanism of death) due to a gun shot wound through the head (cause of death) as a result of being shot (homicide), shooting yourself (suicide), dropping a gun and it discharging (accident), or not being able to tell which (undetermined). All of which are manners of death.

29 Crime Scene Challenge Now that your eyes and brain are warmed up, let’s test your observation skills a bit more. You will have 2 minutes to study the photograph of a crime scene on the next slide. Try to pay attention to details as you will be asked 10 questions about the crime scene! You are not allowed to write anything down until after the time is up. Ready?


31 Do you remember? What color coffee mug was in the picture? Blue Red Yellow 2. When was the deadline? Yesterday Today Tomorrow 3. What time was on the clock on the wall? : : :55 4. How many sticky notes were on the whiteboard? Four Six Eight 5. Which of the following was NOT in the picture? Stapler Trash Can Printer  6. What was the name on the plaque on the desk? Bill Brian Carl  7. What color was the victim's shirt? Black Blue Red  8. How many plants were in the picture? None One Two 9. What was the color of the marker in the desk drawer? Red Blue Green 10. Where was the book in the picture? On a box In the trash can Under the body Kendall/Hunt Publishing Company

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