Unit 7: Crime Scene and Physical Evidence

1. Unit 7: Crime Scene and Physical Evidence Crime scene : anywhere evidence may be located that will explain events, it may be one location or several locations.

2. CORPUS DELICTI“Body of the Crime” • You must prove • that a crime occurred • that the person charged with the crime was responsible for the crime • Top Reasons for Committing a Crime • Money • Revenge • Emotion—love, hate, anger • Source of Evidence • Body • Primary and/or Secondary Crime Scene • Suspect(s)

3. CRIME SCENE TEAM • A group of professional investigators, each trained in a variety of special disciplines. • Team Members • First Police Officer on the scene • Medics (if necessary) • Investigator(s) • Medical Examiner (if necessary) • Photographer and/or Field Evidence Technician • Lab Experts

4. CRIME SCENE INVESTIGATION • Based on the scientific method and the Locard Exchange Principle, logic and forensic techniques • Involves: • Recognition—scene survey, documentation, collection • Identification—comparison testing • Individualization—evaluation and interpretation • Reconstruction—reporting and presenting

5. LEGAL CONSIDERATIONS • One of the fastest ways for an investigator to lose friends at the crime lab is to collect the evidence improperly. • There is nothing worse for a forensic scientist than to painstakingly go through mountains of trace evidence, spend hundreds of hours identifying and comparing pieces that prove the suspect guilty, and then have the whole thing thrown out of court because the evidence was collected improperly at the crime scene.

8. The Fourth Amendment of the U.S. Constitution protects us against unreasonable search of our houses and seizure of our property. • The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particu­larly describing the place to be searched, and the persons or things to be seized.

9. The courts go a long way in admitting physical evidence into a case. • Physical evidence cannot be bribed, it cannot suffer a loss of memory, and it cannot see things from a biased perspective. • Physical evidence is available to both the prosecution and the defense.

11. search warrant. • Investigator must first obtain a search warrant. • The search warrant must be obtained from a judge, and the investigator must give a good reason (probable cause) why they believe the evidence is present. • The warrant must specify the location to be searched and what is to be seized.

12. search warrant. • To obtain a search warrant a police officer must show: • 1. probable cause • The person or thing to be seized • The place to be searched

13. There are four common exceptions that allow a warrantless search and seizure. • 1. Emergency. For example, the police are responding to a phone call by a neighbor about a domestic disturbance. They are standing outside the door of an apartment, and they hear gun­shots and someone calling for help.

14. 2. Prevent destruction of evidence: A fire department does not need a warrant to enter a burning building to put out a fire. • The courts recognize that the chemicals (accelerants) used to start a fire quickly evaporate and that during the time required to obtain a search warrant the evidence may disappear or be destroyed

15. 3. Consent: Once consent is given, an officer can conduct a search as if a warrant had been obtained. It is important to document the consent in some way, such as a written releasesigned by the suspect.

16. 4. Pursuant to a lawful arrest: When an arrest is made, a policeofficer is allowed to search the person and their immediate surroundings. • The definition of immediate surroundings is somewhat vague and is the center of much legal debate.

17. There are five basic steps that an investigator must follow at any crime scene: • Obtain a search warrant. • Secure and protect the scene. • Search the scene. • Document and record the scene. • Collect and package the evidence. • Submit the evidence to the crime lab One of the most important duties of the first responding officer is to secure and protect the crime scene

18. PROCESSING ACRIME SCENE • Isolate and secure the scene • Document the scene • Search for evidence • Collect and package evidence, maintaining the chain of custody • Submit evidence to the crime lab

19. FIRST OFFICERON THE SCENE • A Assess the crime scene and assist those hurt • D Detain the witness • A Arrest the perpetrator • P Protect the crime scene • T Take notes

20. CRIME SCENE SURVEY Walk-through—performed by the crime scene investigator, the first officer and sometimes the lead detective Purpose: • Mentally prepare a reconstruction theory • Note any transient or conditional evidence that could change over time. • Note weather conditions • Note points of entry or exit, as well as paths of travel within the crime scene • Record initial observations of who, what, where, when, and how • Identify special needs within the crime scene for personnel, precautions or equipment and notify superior officers or other agencies

21. DOCUMENTATION • Notes—date and time, description of the location, weather and environmental conditions, description of the crime, location of the evidence relative to other key points, the names of all people involved, modifications that have occurred and other relevant information • Photography—photos of scene and surroundings, mid-range to close-up photos with various angles of each piece of evidence, photos as viewed by any witnesses. • Sketches—inclusion of date, time, scale, reference points, distance measurements, names of investigators, victims, suspects, and a legend (key) • Videography—allows narration (non-subjective) to be included

22. In the O.J. Simpson case, many of the investigators wandered through the crime scene without protective clothing and brought questions of contamination into the trial thus throwing out the evidence. O.J. Simpson case,

23. SEARCH PATTERNS • The crime scene should be searched in a systematic fashion.. • The four standard search patterns used are strip, grid, spiral, and quadrant. • The actual pattern used varies, and the shape and size of the crime scene can influence the choice, as the number of search personnel and the preferences of the lead investigator.

24. 1. spiral search is well suited to round crime scenes,. . A single investigator at an outdoor crime scene often uses the spiral search pattern. It has also been employed in underwater searches. strip or lane search while a strip or lane search is well suited to large areas when there are multiple searchers search patterns

25. A grid search is similar to a strip search but after completing the search in one direction, say east to west, the search is then done at a 90° angle, say south to north. A grid search takes longer to conduct but has the benefit of double-checking the area quadrant or sectorsearch Can be applied to small or large crime scenes. search patterns

27. CRIME SCENE SKETCH Date: August 14, 2005 Criminalist: Ann Wilson Time: 11:35 am Location: 4358 Rockledge Dr, St. Louis, Mo. N

28. RECORDING THE SCENE • The crime scene must be documented in the investigator's field notes as well as in a sketch. • There must also be a visual record of the crime scene consisting of photographs. • While there has never been a case of a crime scene being over documented, there have been many cases where vital clues have been overlooked, lost, or misplaced.

29. COLLECTING AND PACKAGING EVIDENCE • One individual should be designated as the evidence collector to ensure that the evidence is collected, packaged, marked, sealed, and preserved in a consistent manner • Each item must be placed in a separate container, sealed, and labeled • Most fragile is collected and packaged first • Different types of evidence require specific or special collection and packaging techniques • The body is the property of the coroner or medical examiner. The collection of evidence on the body is done by that department

30. PACKAGING Most items should be packaged in a primary container and then placed inside a secondary one. These are then placed inside other containers such as paper bags, plastic bags, canisters, packets and envelopes depending on the type and size of the evidence.

32. The preferred manner of recording a crime scene starts with a camera.. • While digital pictures are fast and easy to print, they are also easy to digitally alter and these alterations can be difficult to detect. • For this reason it is important to make digital pictures as reliable as possible… or use film • Photographs should be taken of everything that could be a potential piece of evidence. • The crime scene can also be videotaped.

34. COLLECTION AND PROPER PACKAGING OF PHYSICAL EVIDENCE • It is extremely important that evidence be collected properly or all its value may be lost. • investigator should never directly come in contact with the evidence • At a minimum, evidence can be collected using forceps or gloves and must never be directly touched by the investigator. • For the purpose of packaging, evidencecan generally be separated into four maincategories,trace, nonbiological, biological, and arson, with general guidelines for each.

36. Any unknown or questioned evidence is collected from a crime scene • Most types of evidence can be sent via U.S. mail except explosives

37. Glass evidence • Glass evidence is packaged in a rigid container so that it does not cut investigator

38. Blood soaked clothing • should be air dried before wrapping and should be packaged in paper bags…this prevents molding

39. Soot from arson • Soot from arson should be placed in a metal can.

40. In the absences of any other container investigators can use druggist fold • One of the most common mistakes made in collecting evidence is forgetting to collect a control

41. One of the most common mistakes made by new investigators when collecting evidence is forgetting to collect controls ( similar type evidence collected away from the area of the crime)

42. In the O.J. Simpson case many of the investigators walked through the original crime scene without wearing protective clothing (hair nets, latex gloves, shoe coverings, and so on) that would keep them from contaminating the scene.

43. On June 12, 1994, the bodies of Nicole Brown Simpson and Ronald Goldman were found mur­dered outside Nicole Simpson's home. • Photographs of the crime scene actually show the investigators walking through the area and scattering vital evidence, such as blood. • Worse yet, some of the investigators then went to the next investigation site, the home of O. J. Simpson, and tracked evidence from the initial crime scene along with them.

45. PHYSICAL EVIDENCE • While almost anything can be physical evidence, it is sometimes helpful to break evidence down into categories: • body fluids: blood, saliva, sweat, and semen • Explosives and incendiaries (arson) : chemicals used to start fires • Fabrics • Illegal drugs: narcotics, stimulants, ect… • Firearms • Glass: fragments and bullet holes • Soil: • Hair: • Fingerprints • Impressions: shoe tire, teeth • Paint • Liquids: biological and hazardous • Metals: poisonous, fragments • Questioned documents • Computer crime • DNA: blood, semen, saliva, body tissues, and hair

46. INDIVIDUAL CHARACTERISTIC EVIDENCE: • Physical evidence is normally classified as either individual characteristic or class characteristic evidence. • Individual characteristic evidence : physical evidence that can be associated with a single, unique source with a high degree of probability. Ex. Fingerprints, DNA, striations on bullet, paint chips • Class characteristic evidence:Physical evidence that can be associated with a group. Ex blood type

47. Evidence Characteristics Class—common to a group of objects or persons ( most evidence analyzed in a crime lab fits here) Individual—can be identified with a particular person or a single source ( if the probability is low enough, class evidence can become individual evidence) Fingerprints Blood DNA Typing

48. Class vs Individual Evidence Which examples do you think could be individual evidence?

49. Class vs Individual Evidence The large piece of glass fits to the bottle—it is individual evidence • These fibers are class evidence—there are millions like them.

50. Class characteristic evidence • Human blood can be one of four different blood groups A, O, B, or AB. • EXAMPLE: LETS say a victim is found dead in his apartment and that he has type A blood. • There is evidence of a struggle, and scrapings from under his fingernails show traces of skin cells and blood. • The blood is typed and found to be type O. • A suspect is arrested, and he also has type O blood. • How strong a piece of evidence is the blood type? • The percentages of the types of blood are well known for various populations, and in the United States are as follows.