Chapter 2

CRIME SCENE EVIDENCE(2.1) Any and all objects that can establish that a crime has or has not been committed or can link a crime and its victim or its perpetrator. *From Locard’s Principle *Value of evidence hinges upon what it can tell the “trier of the fact” (aka – the court) *Evidence must be more probative than prejudicial (must “probe” the question at hand)

Probative vs. Prejudicial Evidence Relevant Evidence: Makes the existence of any fact that is important to the care more or less probable. Probative Evidence: Has the ability to prove/demonstrate something relevant to the case. Prejudical Evidence: Pertains to a matter not previously decided; Establishes a preconceived bias in a matter being decided.

TYPES OF EVIDENCE Physical Evidence is generally recognized to be a material object. Physical evidence is treated/analyzed in one of two ways… Identification analysis or Comparison Analysis

IDENTIFICATION ANALYSIS Describes in detail the components or composition of an unknown sample. *Identify relevant features of a piece of evidence with as much specificity & certainty as possible. *Leads to an unambiguous identification of the material. *Multiple methods are employed to verify the I.D.

COMPARISON ANALYSIS Associates a standard reference sample (an exemplar) with a known origin to a sample of an unknown origin. *Do two samples have a common origin? One-to-Many Matching: Narrows down to a group of matches; Often from a database. One-to-One Matching: Comparing to one/few reference standards.

CLASS vs. INDIVIDUAL CHARACTERISTICS Class Characteristics Place the piece of evidence with a particular group. Individual Characteristics Relate the sample to a unique and specific origin with a very high degree of certainty

Class Evidence, cont. Class evidence does not usually allow for the direct connection between two individual items BUT is very powerful when coupled with other class characteristics. *Still does not provide one-to-one matching but with multiple class characteristics, a match can be narrowed down even further. *Fingerprint pattern *Type of shoe worn *Type of vehicle *Hair, eye, skin color

Individual Characteristics, cont. *A fingerprint matched to one specific person. *The wear pattern on the bottom of a person’s shoe *The size, location and severity of a dent in a car *Dental records (for human identification)

LEGAL EVIDENCE (2.2) Fourth Amendment: 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 open probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

The Fourth Amendment… *Guards against unreasonable searches & seizures of a person & their property *Provides for times when it has been determined a search is necessary for public safety. These two instances are… -Those that require a warrant before the search -Warrantless search Or, a person may just give consent to a search.

Obtaining a Search Warrant -Issued by a judge -Police must show probable cause that they are likely to find illegal items or criminal evidence. -Police must present the judge objective facts or evidence that support that they will find what they are looking for -Search warrants are for a specific place, time, and describes what items are to be looked for. Only these items may be seized.

Plain View Doctrine Police officers do not need a warrant to seize items that are plainly visible from a place that the officer has a right to be. Items in plain view do not fall under the 4th amendment’s provisions.

Fruit of the Poisonous Tree Doctrine

Justifications for a warrantless search: 1. Consent 2. Searches during legal arrests 3. Emergency circumstances -Entering a smoke-filled building -Destruction of evidence 4. Plain view 5. Airport, border, and sea searches 6. “Stop and frisk” 7. Inventory searches of a seized item (ex. Car) 8. National security (USA Patriot act) -email, medical/financial records 9. Administrative searches -Fire, electrical, gas inspectors will alert police

Important Court Cases Mincy v. Arizona: Drug bust resulting in the death of an undercover police officer, wounding others. *Homicide detective spent 4 days searching & seizing 200-300 pieces of evidence. Supreme Court ruled the evidence was inadmissible A warrantless search based on an emergency is limited in duration.

Michigan v. Tyler: Fire in a furniture store was; Scene was searched for three weeks. *Supreme court said that the evidence was not properly collected and ruled it inadmissible. Entry to a fire requires no warrant…and officials may remain there for a reasonable time to investigate. The crime scene was not controlled by police – left abandoned in between searches.

The Evidence Collection and the Evidence Team (2.3) The investigator must recognize physical evidence and properly preserve it for laboratory examination. This includes information from witnesses. Failure to process correctly will often result in the loss of potentially key forensic information.

PROCESSING THE CRIME SCENE The first officer arriving at a crime scene: 1) Securing & isolating the scene 2) Recording the scene 3) Searching & collecting evidence 4) Packaging, transporting and storing evidence

1) SECURING & ISOLATING THE SCENE *Ensure that the scene is safe *Be alert to any person or vehicle leaving the scene *”Watch the watchers” *Provide emergency medical treatment *Establish a perimeter Separate victims, witnesses, medical personnel, bystanders *Designate a lead investigator

2) Recording The Crime Scene Document the location, condition & appearance of persons and items within the crime scene. Take note of… *Weather conditions *Locations of objects within the scene *Identification of personal items *Conditions of items

Locating Physical Items Triangulation: Items are measured to two fixed reference points in the crime scene area. Accurately places the item. Azimuthal Locating: Uses a compass to locate evidence by measuring angles & distances to a known geographic point. Coordinate Mapping: Area is broken down into a grid and each square is searched individually. Electronic Methods: Mapping a scene with GPS, lasers, etc.

Measurements & Information used for… Measurements & Information used for… *Constructing a detailed ‘map’ of the scene -Rough Sketch: Completed at the crime scene & includes all measurement lines -Final Sketch: Completed after leaving the scene.

Necessary to form a permanent record of the scene PHOTOGRAPHY Necessary to form a permanent record of the scene *Photograph evidence in as pristine a state as possible. *Take overview (wide angle) photographs to show the context of the entire scene *Take close-ups of the evidence to show the detail of the item.

3) SEARCHING & COLLECTING EVIDENCE The lead investigator usually determine the type, extent, and location of the searches that need to take place. Types of Search Patterns: *Grid search *Inward / Outward spiral *Parallel *Zone

Inward / Outward Spiral – Can walk inward towards center of boundries or outward. Conducted by one person Evidence MAY be missed Grid - One or two investigators Walk boundary to boundary Good when boundaries are clear.

Parallel Search – Team members walk in a straight line at the same speed from one end of the scene to the other. *Large areas, many team members

A B C D Zone Search: Multiple investigators Large area Area is divided into equal zones an assigned an investigator to thoroughly search their zone. A B C D

What to Look For at the Crime Scene Evidence collected depends on the crime scene. Homicide – Search centers on weapon/body *links to suspect Collect possible carriers of trace evidence * Clothing that could carry evidence * Vacuum areas that may have hairs/fibers * Protect hands of the victim

4) PACKAGING, TRANSPORTING & STORING EVIDENCE (Collection & Preservation of Evidence) *Evidence must be collected/packages so contamination does not occur *Evidence must be protected from damage and degradation *Different types of evidence require differing methods of packaging and storage based upon the characteristics of the evidence itself. Table 2.3.1 Selected Examples of Packaging for Different Types of Evidence

Packaging, Transporting & Storing Evidence, cont. Chain of Custody: Documents the chronological control from the time that evidence is first discovered until it is needed in court. -Details every transfer -Details collection, analyses & storage -Dates & times are included with all info. Serves as a provable record of every moment of the evidence’s existence after it’s collected. Breaks in the chain of custody will make it unlikely the evidence is useful in court.

Packaging, Transporting & Storing Evidence, cont. Evidence Team: Each person has a well-defined set of tasks and responsibilities *Team Leader- Directs the access to the site; Responsible for overall operation of the search/recovery of evidence; Sets boundaries; Determines search method; Assigns personnel to tasks; Coordinates with all groups present *Photographer- Documents the site before & during processing begins; Must include scale with their photos

Packaging, Transporting & Storing Evidence, cont. Evidence Team, cont. *Sketch/Map Preparer- Produces detailed map of scene; Rough sketch produced. *Evidence Recovery and Recorder Personnel- Search, locate, collect and package evidence for transporation to lab; Record a description of the evidence; Begins the chain of custody. *Specialists- Necessary for complex crime scenes. Specialists listed in Ch. 1; In addition – DNA tech., Blood spatter experts, Divers, Fingerprint techs., Canine, Ecologist