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 basic order 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.

Initial Scene Perimeter

Area entailing the actual crime scene.

Area outside controlled perimeter where on-lookers and media may gather.

A Single Barrier Perimeter

A single barrier is fine for initial purposes.

It does not providea sufficient bufferfor long term scene effort.

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.

Inner Scene Perimeter

Outer Scene Perimeter

Area entailing the actual crime scene.

Working area, evidence holding area and staging point for equipment, it also provides a physical buffer between

the actual scene and unauthorized individuals.

Area outside the controlled perimeters.

Multi-level Containment

Two perimetersprovide for threeareas of access.

This keeps supportpolice out of theactual scene andothers at a safe distance.

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 Out

1750

SA Brown – Homicide

Scene Processing

1759

Smith/ME Investigator

Scene exam

1823

1800

H. Jones – CS Unit

Scene Processing

1800

L. Marshall- CS Unit

Scene Processing

1817

Chief Kyle

Scene visit

1833

1817

Maj. Darren – PIO

Update by Homicide

1833

The 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.

Area to be searched

SearchWidth 1

SearchWidth 2

Terrain at Width 1 Terrain at Width 2

Terrain and Search Swathe Size

Terrain has a significantaffect on the size of

a search swathe.

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 sizeof 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

Start

Start

End

Narrowing 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.

Strip Search

Start End

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.

Start Line

End Line

Line Search

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.

Grid Search

Start

End

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 E

Zone A Zone D

Zone B Zone C

Zone F

Zone G

Zone J Zone H

Zone I

Zone Search - Small Confined Areas

An example is the car. No pattern search will work, so zones are created that are searched individually.

Zone 1 Zone 2

Zone 3

Zone 4Zone 5

Zone 7

Zone 6

Zone 8

Zone 9

Zone Search - Breaking Up a Larger Scene

An example is a home and the grounds. To keep perspective, the grounds are broken up into zones, which are then searched individually using a standard 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 Equipment

1. Goggles/eye protection - splash andmucous membrane tissue protection.

2. Face/particle mask - inhalation protection.

3. Tyvek suit - impervious to liquidcontaminants.

4. Rubber gloves - impervious to liquidcontaminants.

5. Booties - splash and contact protectionfor footwear.

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3

4

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.