Module 3B The First Officer & Systematic Searches. Forensic Science Teacher Professional Development

Transcription

1 Module 3B The First Officer & Systematic Searches Forensic Science Teacher Professional Development

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3 Unit 1.4: Responsibilities of First Responding Officers 0 The first level of assessment is conducted by the initial police responder, whose goal is to secure the scene and to coordinate the resources. This officer is responsible for securing the scene, not only for the safety of the civilians and additional responding officers, but also for the preservation of the scene and its physical evidence.

4 Unit 1.4: Responsibilities of First Responding Officers The primary objectives of the first responding officer are the following: Prevent casualties Provide emergency care Secure/control the scene and all those within Document all pertinent information Release the scene to appropriate personnel It is always possible the crime is ongoing and the first responder must assume the scene is unsecured and dangerous. The primary concern is always for the safety of the officers and others in the area, so the perpetrator(s) should be detained if present. Consideration should be given for the potential presence of any natural and/or handmade hazards that might inhibit the investigation or present harm to people.

5 Unit 1.4: Responsibilities of First Responding Officers As soon as the scene is considered safe, the officer may provide emergency care and call in the necessary emergency services. Next, the officer needs to isolate the scene and determine its boundaries. The scene is not solely defined by the location of the crime but is comprised of the staging and planning areas; paths leaving the scene; paths between the scene and removed physical evidence; and, if applicable, paths to and from the secondary location of interest.

6 Unit 1.4: Responsibilities of First Responding Officers The following should be considered in determining the initial perimeter: Primary focal points that hold important physical evidence (bodies, weapons, evidence of a struggle, blood spatter, etc.) Natural entry and exit points such as doors and windows Secondary scenes (perpetrator s staging area, areas where evidence was left or removed) The scene boundaries can be physically roped off with crime scene tape, traffic cones, barricades, police vehicles, and/or additional police officers on the perimeter.

7 Figure 2 Indoor Crime Scene Marked Off

8 Unit 1.4: Responsibilities of First Responding Officers Figure 3 Outdoor crime scene marked off

9 Unit 1.4: Responsibilities of First Responding Officers Initial information obtained by first responding officers includes what they were told about the situation and who provided that information, i.e., who reported the incident/called 911 and what they said was occurring; identification of all persons at the scene upon their arrival; witness statements obtained at the scene; their initial observations; names and actions of emergency personnel; time of their arrival and their actions at the scene; and names and time of arrival/departure of additional police personnel.

10 Unit 1.4: Responsibilities of First Responding Officers The first responder notifies supervisors and advises them on the personnel needed for the investigation. The first responder can then release the scene to the detectives and crime scene technicians after a detailed debriefing. As additional police personnel arrive, the first responder documents their information which includes their names, badge numbers, time of arrival, etc. The first responder also maintains control of the civilians and media in the area by keeping them behind the established boundaries.

11 Unit 1.4: Responsibilities of First Responding Officers Crime Scene Technician Initial Assessment Once the crime scene team arrives, they further assess the scene to ensure that the boundaries are established and have encompassed all areas of concern; the team will expand the perimeter if necessary. The scene investigator establishes the inner perimeter that incorporates the actual crime scene, a second perimeter that serves as a staging area for equipment and evidence collection, and a third perimeter that separates the public and media from the scene. Establishing the boundaries and managing their access serve to limit scene contamination.

12 Figure 4 Multilevel containment in a crime scene

13 Unit 1.4: Responsibilities of First Responding Officers Once the crime scene perimeters are delineated, investigators establish a single path of entry and exit into the scene. Investigators also use the initial assessment to determine the types of search methods they will employ and the personal protective measures necessary to limit contamination.

14 Unit 1.4: Responsibilities of First Responding Officers Five basic factors are considered to contribute to scene contamination: 1. Weather plays a big role in contamination, especially in outdoor scenes. 2. Relatives/friends of a victim may feel the need to cover up an embarrassing situation or remove suicide notes to protect the family name. 3. Suspects could destroy or remove evidence. 4. Curious civilians, crime scene souvenir collectors, and thieves may introduce trace evidence (fingerprints/footprints) or remove evidence. 5. Other police officers, especially those not assigned to the case, may come to offer misguided help or come out of sheer curiosity. They can also introduce trace evidence or move evidence without documentation.

15 Unit 1.4: Responsibilities of First Responding Officers Every effort is made to preserve the scene and prevent contamination, so in order to avoid the common contamination factors, investigators put up tents or shields to reduce damaging effects of weather; wear full suits and shoe covers to prevent transferring evidence or tracking in contaminants; establish one route in and out of the scene; keep the number of officers to a minimum and don t allow extraneous police personnel; keep relatives, media, and other civilians out of the scene; and do not allow detained suspects back into the scene.

16 Unit 1.4: Responsibilities of First Responding Officers Finally, investigators use the initial assessment to document important observations, such as their time of arrival; the exact location of the scene and GPS coordinates if applicable; officers, EMS, relatives, witnesses, etc. present on the scene; the condition and position of a body, if applicable; information concerning the scene/death from the first responder; weather conditions; lighting conditions; and point of observations for potential witnesses.

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18 Unit 1.5: Conducting a Systematic Search for Evidence Search patterns and case examples Systematic searches of the crime scene are done to locate, identify, and collect physical evidence. The method of search depends on the type, location, and size of the scene. Whatever method is chosen for the search, there are several factors that can affect the process: The nature of the area, like whether an area is cluttered, sparse, or densely vegetated, may affect the search. It would take an investigator longer to search a field with tall grass than an empty parking lot.

19 Unit 1.5: Conducting a Systematic Search for Evidence Search patterns and case examples, continued The amount of natural light and the presence of electricity will affect how much of the scene is visible at one time and therefore, how many investigators are needed to monitor the scene. Environmental conditions, such as inclement weather or extreme weather conditions, can interfere with or inhibit the search. Size of evidence may affect the search. The smaller the evidence the more involved the search; e.g., looking for fibers versus a handgun.

20 Unit 1.5: Conducting a Systematic Search for Evidence After considering these factors, investigators can choose the most appropriate search method/pattern for the scene. There are five search methods/patterns used by investigators: a) Strip/line search b) Grid search c) Spiral search d) Quadrant/zone search e) Ray/wheel search

21 Unit 1.5: Conducting a Systematic Search for Evidence a) Strip/Line Search Strip Search: Investigator starts at one end of the scene, walks in a straight line to the opposite end, then reverses direction and searches the adjacent lane. The method can be done by a single searcher. Line Search: Instead of reversing direction every other lane, one investigator searches each lane in the same direction. The line search uses multiple investigators.

22 Unit 1.5: Conducting a Systematic Search for Evidence The strip/line search is ideal for scenes with defined boundaries, larger exterior locations, or areas with uneven terrain. Figure 5 Line Search

23 Unit 1.5: Conducting a Systematic Search for Evidence b) Grid Search: The search area is divided into two sets of lanes that run perpendicular to one another, i.e., lanes that run north to south and lanes that run east to west. There is one investigator assigned to each direction. Grid searches are used for scenes with wellestablished boundaries. Figure 6 Example of Grid Search

24 Unit 1.5: Conducting a Systematic Search for Evidence c) Spiral Search: This search can be conducted with one investigator where he or she works in either an inward spiral or outward spiral. Spiral searches are most often employed in interior scenes. Figure 7 Spiral Search

25 Unit 1.5: Conducting a Systematic Search for Evidence d) Quadrant/Zone Search: This method divides the scene into zones or quadrants, and an investigator searches each one thoroughly and independently of the others. 0 There are two types of scenes where this approach is employed: 1. Large scenes that can be broken down into smaller, more manageable quadrants 2. Spaces that have existing quadrants, such as a vehicle Figure 8 Quadrant/Zone Search

26 Unit 1.5: Conducting a Systematic Search for Evidence e) Wheel/Ray Search: This method is the least preferred because it does not completely cover the search area. It uses several searchers that either start from the outer boundaries in a line to the center of the scene or conversely start at the center and work in rays outward. The problem lies in the fact that the spaces between the rays are not allotted a searcher. Figure 9 Flagged Evidence To best control the search effort, the pace of each method is set by the slowest searcher. Evidence is marked or flagged as it is found by the searcher and then a crime scene technician follows behind to collect and process the item.

27 Unit 1.5: Conducting a Systematic Search for Evidence Locating and Identifying Evidence: An investigator s experience plays an important role in his or her ability to locate and identify the evidence. The success of the crime scene process depends on the investigator s ability to recognize and discriminate between what is and what is not relevant to the scene. Investigators determine the scope of the search and the types of evidence to look for based on their theory or hypothesis of the crime. Their theory of the crime is dynamic and adjusts as the evidence is found and analyzed. It is important that investigators keep an open mind and never make assumptions even in open and shut cases, as important evidence can be overlooked.

28 Unit 1.5: Conducting a Systematic Search for Evidence The following are often searched for physical evidence: Areas of forced entry Escape routes/exits Suspect Victim Weapons Possible weapon locations Vehicles Suspect s residence Primary scene where assault occurred Place where body was removed from Secondary scenes or body dump locations

29 Unit 1.5: Conducting a Systematic Search for Evidence When looking for evidence, investigators base the search principles on Locard s Principle of Exchange: with contact between two items, there will be an exchange of evidence. This principle means that something will transfer from the suspect to the scene and from the scene to the suspect; this also applies to the victim. Investigators look for two characteristics of physical evidence: class characteristics and individual characteristics.

30 Unit 1.5: Conducting a Systematic Search for Evidence Class characteristics are defined by the National Institute of Justice as measurable features of an item that indicate a restricted group source based on design factors determined prior to manufacture. Class characteristics may be found to be like or consistent with a questioned source although not uniquely identifiable with that source. A technician might say that the wound pattern is consistent with a Craftsman ball-peen hammer but cannot definitively identify the suspect s Craftsman ball-peen hammer as the item that made the wound without more evidence. Examples of class characteristics would be the width of the tip of a screwdriver, bloodstains, blood types, or tool marks.

31 Unit 1.5: Conducting a Systematic Search for Evidence Individual characteristics are defined by the National Institute of Justice as marks on an object produced by the random imperfections or irregularities on the surface of the tools used to manufacture the object. These characteristics are produced subsequent to the manufacturing process and typically are seen on the microscopic level. Individual characteristics can be produced on an object by use, abuse, and/or corrosion and are uniquely identifiable with a source. Examples of individual evidence would be fingerprints, striations on a fired projectile, DNA, or shoe wear impressions. If the suspect s Craftsman ball-peen hammer had multiple chips in the surface unique to its previous usage, and those characteristics transferred to the wound, then the chips in the surface would be considered individual characteristics.

32 End of Module 3B Forensic Science Teacher Professional Development