Presentation on theme: "Crime Scene Investigation"— Presentation transcript:
1 Crime Scene Investigation FORENSIC SCIENCECrime SceneInvestigation
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 LeeChief 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 sceneD Detain the witnessA Arrest the perpetratorP Protect the crime sceneT 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 EvidenceTestimonial 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 committedEstablish key elements of a crimeLink a suspect with a crime scene or a victimEstablish the identity of a victim or suspectCorroborate verbal witness testimonyExonerate the innocent.Give detectives leads to work with in the caseSource:
7 Adapted from http://www.feinc.net/cs-proc.htm Crime Scene ProtocolStep 1: InterviewThe 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: ExamineThe 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: DocumentThe 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: ProcessThis 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 evidenceClose-ups of each item of evidence (use a scale)
9 Sketchesare important because they relationships of items to other thingsThey must be clear and show the coordinate position of each item of evidence
14 Processing Physical Evidence In order for evidenceto be admissible, itmust be:Legally obtainedProbative—actually prove something (relevant)Identify the itemMaintain the chain of possessionKendall/Hunt Publishing Company
15 Physical EvidenceTransient Evidence--temporary; easily changed or lost; usually observed by the first officer at the sceneOdor--putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smokeTemperature--of room, car hood, coffee, water in a bathtub; cadaverImprints and indentations--footprints; teeth marks in perishable foods; tire marks on certain surfacesMarkings
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:BiologicalChemicalPhysicalMiscellaneous
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 conditionsSmoke--color, direction of travel, density, odorFire--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 mileageBody--position; types of wounds; rigor, livor and algor mortisScene--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 DeathWarmColdNot stiffStiffNot dead more than 3 hrsDead between 3 and 8 hrsDead 8 to 36 hoursDead more than 36 hours
24 THE BODY Livor MortisLivor 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 MortisAlgor mortis is body temperature. At a crime scene, it can be obtained in two different ways.Rectal temperatureLiver temperature
26 Time Frame of Death Condition Appearance Periphery blood drying 30 min to 2 hrsBlue-green discoloration of skinRight and left area of abdomen 24 hoursEntire abdomen 36 hoursBloating to 48 hoursSkin slippage 4 to7 daysAbsence of smell from bones more than 1 year
27 Time Frame of Death Eyeball Changes Condition AppearanceCornea drying (eyes open) minutesCornea drying (eyes closed) 2 hoursCorneal cloudiness (eyes open) less than 2 hoursCorneal cloudiness (eyes closed) 12 to 24 hoursEyeball 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 ChallengeNow 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 Yellow2. When was the deadline? Yesterday Today Tomorrow3. What time was on the clock on the wall? : : :554. How many sticky notes were on the whiteboard? Four Six Eight5. 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 Two9. What was the color of the marker in the desk drawer? Red Blue Green10. Where was the book in the picture? On a box In the trash can Under the bodyKendall/Hunt Publishing Company