Practical Crime Scene Processing and Investigation Greg Dagnan Chapter 5 - Assessing the Scene
Learning Objectives Identify the purpose of assessment. Describe the function of barriers in maintaining scene integrity and contamination control. Identify and explain three factors when managing scene access. Identify the two approaches to team formation.
Learning Objectives .. continued Identify and explain the five basic search patterns used in crime scene examination. Identify basic personal protective measures for crime scene team members. Explain the relationship of the media and police as it pertains to crime scenes.
Crime Scene Processing Activities The six crime scene activities and their basicorder are:– Assessing– Observing– Documenting– Searching– Collecting– Analyzing
Assessing Assessment of the scene assists the investigator in making a decision on what to do, when to do it, and what resources may be required. Assessment must be accomplished before taking any action, but assessment is an on-going activity as well. The investigator is constantly assessing the scene throughout processing.
Five Issues of Assessment Assessment involves five basic issues, these are: – Scope and complexity of the scene. – Scene integrity and contamination control. – Team approach and composition. – Search methods to be used. – Personal protective measures. Assessment by the crime scene team always involves a debriefing of the initial responders.
Debriefing of Initial Responders Debriefing of the initial responders seeks to answer the following questions: – What is the scope and nature of the scene? – What actions or alterations have been taken or noted by first responders (including EMS)? – What is the status of involved parties? – What level of security has been established and what further security actions are required? Their observations may not always be accurate, but they give the team a point to start from.
Scene Scope Investigators should re-access the scene boundary after debriefing. They use the same criteria as the initial officer: – Primary focal points. – Avenues of entry or exit. – Secondary scenes. Based on experience they may recognize minor nuances that require expanding the perimeter.
Contamination Control Once the crime scene team is confident of the scene scope, the team should act to further isolate the crime scene. Initial perimeters are often a single barrier, leaving little if any buffer between the crime scene and the on-lookers.
A Single Barrier Perimeter Initial Scene Perimeter A single barrier is fine for initial purposes. It does not provide a sufficient buffer for long term scene Area entailing the actual crime scene. effort. Area outside controlled perimeter where on-lookers and media may gather.
Multi-level Containment Multi-level containment involves two barriers which creates three areas of access: – Inner Scene: This is the actual crime scene, where only authorized investigators and crime scene technicians operate. – Working Area: This is an area surrounding the inner scene, where other support police may enter, equipment is staged and evidence is brought to. – Outer Area: This is everything on the outside of the second barrier, where on-lookers, media and others may gather.
Multi-level Containment Outer Scene Perimeter Two perimeters Inner Scene Perimeter provide for three areas of access. This keeps support police out of the Area entailing the actual crime scene. actual scene and Working area, evidence holding area and staging point others at a safefor equipment, it also provides a physical buffer between the actual scene and unauthorized individuals. distance. Area outside the controlled perimeters.
Managing Access to the Scene Once the perimeter is established, a decision must be made on how the team will manage access to the scene. This involves identifying actual access points for the team and establishing entry control points. Determining how to access the scene isn’t always difficult, but it isn’t always simple either.
Access Points to the Scene Determining how to access the scene is a function of three factors: – What avenues of approach are available? – Will these points expose operations to media scrutiny? – What avenues of approach or exit did the offender use? With these three factors in mind the crime scene team decides what points they will use to access the scene for processing purposes.
Access Points Issues What avenues of approach are available? – There may only be one point of access. – Look for others. Will these points expose operations to media scrutiny? – Is there a way to shield the access point from the media and their prying eyes? What avenue of entry or exit did the offender use? – These are areas rich in evidence, so the team can’t simply tromp through them.
Entry Control Logs The scene often requires multi-level containment, with several perimeters. Entry control logs can certainly be used at any perimeter, but they become a hindrance to operations. The inner perimeter (the true crime scene) requires an entry control log.
Crime Scene Entry Control LogTime In Name/Unit Reason at Scene Time Out1750 SA Brown – Homicide Scene Processing1759 Smith/ME Investigator Scene exam 18231800 H. Jones – CS Unit Scene Processing1800 L. Marshall- CS Unit Scene Processing1817 Chief Kyle Scene visit 18331817 Maj. Darren – PIO Update by Homicide 1833The entry control log keeps track of who entered the scene, when,why and when they left. It’s serves to validate scene integrity.
Crime Scene Team Approach There are two approaches for creating crime scene teams: – By Area - single group of investigators is responsible for all activity in the scene. – By Function - specific groups are formed to handle different scene processing aspects (e.g. photo team, sketch team, latent team) In normal scenes, custom and size of the organization will often determine the approach.
Team Approach … continued In complex scenes, issues of size or resources may require the organization to alter its approach. – Lack of equipment resources to handle multiple scenes, may force a functional approach. – If equipment resources are not an issue, but size is; area teams may be necessary to handle small zones with in a larger scene. – The need for specialty examinations on scene may force a functional approach.
Crime Scene Team Composition Crime scene teams have to be manned appropriately. It is difficult to manage crime scene activity if the teams are under staffed. Different stages of the processing methodology demand different levels of minimum manning.
Team Composition … continued Photography teams require two individuals. – One operates the camera. – Second maintains the photo log and assists. Sketch teams require three individuals. – Two take measurements. – One annotates the sketch and takes notes. – In a pinch, two can do the job, but be careful as notes and measurements get mixed up.
Team Composition … continued Evidence Collection teams require two individuals. – One containerizes and physically collects the items. – A second maintains the evidence log. Search teams are a matter of circumstance, but always require a minimum of two individuals. – No two people survey or perceive the same way, so two sets of eyes prevents items from being overlooked.
Search Considerations Ultimately, some form of search must be conducted at the scene to locate evidence. The particular search pattern chosen is a function of the situation. No matter what search pattern is chosen the crime scene team must decide on a search swathe size.
Search Swathe Size The search swathe is the area that any given searcher is viewing at any given moment in the search. How tight or how broad this search swathe will be is a product of several considerations: – Nature of the ground being searched. – Lighting considerations. – On-scene environmental conditions. – Size of the item being searched for.
Terrain and Search Swathe Size Terrain at Width 1 Terrain at Width 2 Terrain has a significant affect on the size of a search swathe. Search Search Width 1 Width 2 Area to be searched
Lighting and Search Swathe Size Available lighting has a significant affect on the size of a search swathe. Have alternate lighting systems available, including: work lights and Alternate Light Sources (ALS).
Environmental Conditions Extreme heat or cold can affect the ability of the searcher. Wind, rain, fog and other factors may also impede the searchers ability. Any of these conditions may demand narrowing the search swathe to preclude missing items.
Size of the Item Being Sought In focused searches the size of the item being sought can affect the size of a search swathe. Sometimes we do directed searches, looking for a specific object, which impacts our decisions. It is one thing to look for a gun in the grass, its another to look for a shell casing.
Search Patterns There are five basic crime scene search patterns: – Circle search. – Strip or line search. – Grid search. – Zone search. – Point to point search. Each pattern works in a variety of circumstances, but no single pattern works in every situation.
Circle (a.k.a. Spiral) Search Excellent pattern in most interior or confined exterior scenes. Not effective in large exterior scenes or cluttered areas that impact on the circular movement. Searcher moves inward or outward from a starting point.
Circle Search End End StartNarrowing Circle Widening Circle
Strip Search Excellent in exterior scenes where a large area must be examined. Visual alignment to the strip is good for most situations, but as the area to be searched grows, it becomes more difficult to maintain a visual reference of the lanes. Physically laying out the strips with string or tape can help maintain the order.
Line Search Variation of the strip search, where multiple searchers follow a single strip in one direction, while on-line with each other. Excellent for exterior scenes over rough terrain. Usually requires supervisor(s) to maintain the direction and alignment of the involved searchers.
Grid Search The grid search is another variation on the strip search. Searchers follows strips in one direction, then cuts across the scene in another set of strips, oriented 90 degrees to the first. Provides for multiple views of the same ground by the same searcher from different perspectives.
Zone Search The zone search is used in several variations: – To deal with small confined spaces where no patterned search will work. – To break a larger scene up into functional areas, that are then searched using some other patterned technique.
Zone Search - Small Confined Areas Zone G Zone B Zone CZone J Zone F Zone E Zone H Zone A Zone D Zone I An example is the car. No pattern search will work, so zones are created that are searched individually.
Zone Search - Breaking Up a Larger Scene Zone 6 Zone 5 Zone 4 Zone 7 Zone 9 Zone 3 Zone 8 Zone 1 Zone 2 An example is a home and the grounds. To keep perspective, the groundsare broken up into zones, which are then searched individually using astandard pattern technique.
Point to Point Search Not widely used in the United States. Searchers move from one focal point to the next, creating cleared pathways to and from each. They do not stray from these pathways. Each focal point is dealt with before moving on to the next.
Assessing Crime Scene Hazards A variety of hazards to the crime scene technician exist in the scene. These include: – Bio-hazards from blood or body fluids. – Structural hazards in fire and explosion scenes. – Chemical and inhalation hazards in fire scenes. – Inhalation and chemical hazards from on-scene processing techniques. – Inhalation and explosion hazards associated to drug labs. – Bio-chemical hazards associated with terrorism.
Crime Scene Hazards ... continued Each scene must be assessed for any obvious hazards. Any risks associated to the hazard should be mitigated, if possible, before exposing team members to the hazard. The use of personal protective equipment (PPE) will mitigate or reduce exposure to many common hazards (e.g. bio-hazards, chemical hazards)
Personal Protective Equipment1. Goggles/eye protection - splash andmucous membrane tissue protection. 1 22. Face/particle mask - inhalationprotection. 33. Tyvek suit - impervious to liquidcontaminants. 44. Rubber gloves - impervious to liquidcontaminants.5. Booties - splash and contact protectionfor footwear. 5
Media Issues Assessment involves aspects of dealing with the media (e.g. what information will be held back, how much photo or video access will they get). The media are often viewed in an antagonistic fashion by the crime scene investigator. Use caution when dealing with the media, but treat them as professionals.
Media Issues … continued Police are the gate-keepers. We decide how much access to allow and what information to release. Don’t speculate, don’t lie and if you’re not prepared to release information, then say so. Assign experienced officers as the Public Information Officer and then work as a team to decide what information to release.