Practical Crime Scene Processing and Investigation

Greg Dagnan

Chapter 4 - Processing Methodology

Learning Objectives

Identify the six basic activities related to crime scene investigation.

Identify the normal sequence of these activities.

Explain how this sequence helps prevent the three basic threats to crime scene integrity.

Learning Objectives .. continued

Explain why an activities intrusiveness affects the order in which it is accomplished.

Define what is meant by “going back” in the processing methodology and explain why this concept is important.

Crime Scene Processing Methodology

There is no one “right” way to process a scene.

There are however “wrong” ways to process a scene, which in effect open the door to crime scene integrity threats.

The normal crime scene involves six sequential activities.

Basic Activities of Crime Scene Processing

These six 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.

Assessment is a continuous activity, the investigator is constantly assessing the scene.

Assessing … continued

Assessment includes answering issues such as:– How complex is the scene?

– Is there fragile evidence?

– What resources are required?

– Are there inherent risks and if so how can they be mitigated?

It begins the processing task and defines the procedures that will be employed.

Observing The most common activity involved in crime scene

processing is observing.

Critical observation is the act of mentally registering the condition of the scene and artifacts found in it.

Observation is inclusive in assessing the scene but always precedes the other activities.

Observing … continued

Observing by itself is a non-intrusive action, but it often leads to ad-hoc “search” behavior.

In the initial stages, observing is always conducted in a non-intrusive fashion.

The investigator consciously acts to only observe and not move or alter items in the scene as they observe them.

Documenting Documenting the scene involves a variety of actions.

These include:– Creating written notes of observations.– Obtaining photographs of the scene in-situ.– Video taping the scene.– Creation of crime scene sketches.

Documenting the scene involves both non-intrusive and intrusive actions, so in the documentation step there is an order as well.

Documenting … continued

This order goes from least intrusive to most intrusive, typically following this sequence:– An investigative walk through, creating written notes of

basic observations.

– Photographing the scene in-situ, without altering or changing it.

– Video-taping the scene.

– Sketching and measuring the scene.

– Close-up photography of specific details and artifacts that may require manipulation.

Documenting … continued

This order allows the investigator to capture the complete scene context, without altering that context. For example:– The investigator makes written notes of a revolver on the floor

(e.g. brand, caliber, location).

– The unaltered revolver is captured in the photographs in its exact position.

– The unaltered revolver is included in the sketch and measurements are taken documenting its exact position.

– It is then handled and photographed to show cylinder condition and other details.

No part of the items context has been lost.

Searching The nature of crime scene searches are always

intrusive, they alter the original condition of the scene forever.

To properly search, the investigator must move through the scene, items have to be moved and all surfaces examined.

Because of this searches are accomplished in stages.

Searching … continued

The initial observation is a form of visual search.

True initial searches are done with limited alteration of the scene to prevent disturbing any unobserved evidence.

Later searches are extremely intrusive, often requiring dismantling and movement of objects in the scene.

Collecting Collecting evidence is a very intrusive action.

Once collected, we have disturbed the context of the item and scene forever. There is no undoing the act of collection.

Unless there are issues of fragile evidence , collection of evidence is accomplished only after all scene context is documented.

Collecting … continued

Different forms of collecting evidence result in different levels of alteration. Thus collection may be sequenced as well. Examples:– Recovering a revolver or casing from the floor has no impact

on the remaining scene context. It creates no further harm.

– Recovering a bullet from a wall, requires damaging the wall and may introduce wall board dust into the scene, affecting other areas.

Extremely intrusive collection activities are always conducted last in the collection stage.

Analyzing/Processing Analyzing/processing the scene is the last step.

It often involves significantly intrusive behaviors, including:– Large scale latent print processing of walls and furniture.

– Chemical enhancement of latent prints or bloodstains on floors, walls or objects.

– Forensic analysis of specific objects of evidence at the crime lab.

Applying the Basic Steps Every action taken is done so to capture as much scene

context as possible without introducing alteration.

A basic sequence of activity will assist in this endeavor, but unique circumstance may require adjustment.

The crime scene investigator constantly assesses the situation and adjusts their actions accordingly.

Going Back in Sequence

The crime scene investigator is constantly encountering new evidence.

This requires stepping back in the process to play catch up. Example:

– By the collection step, all items have been photographed, sketched and documented in notes. If we move an object and find a bloody fingerprint; we have to go back to earlier steps for that fingerprint making notes, photographing the item and sketching its location.

Going Back in Sequence

This “going back” is a constant behavior. In both the search and collection phases it is routine to encounter new evidence.

A failure to stop and go back, results in partial documentation. Where critical information is lost and not documented.

A Processing Methodology Although there is no one “right” way to

accomplish crime scene processing, there are established methods.

Many involve checklists and other similar documents.

The following is a tried and true processing methodology.

Step 1 - Initial Notification

As did the initial responder, the investigator must document the information that is presented to them. – Who contacted them?– What were they told?– How did that individual come to know the information?

Remember: The call you got isn’t the call you get! Expect the unexpected, but also know where the discrepancies began.

Step 2 - Coordination, Assessment and Team Callout

Assess the situation:– Is this “my” jurisdiction?

– How complex is the scene and what and who do I need here?

Assessment includes:– Verifying the scene location.

– Making note of environmental conditions.

– Seeking out the initial responder.

Step 3 - Conduct Initial Observations

Conduct an initial scan of the scene, specifically look for:– Central theme items (primary focal points)– Victims– Fragile evidence– Avenues of entry or exit– Secondary scenes

Act on fragile evidence immediately, take action before it is lost.

Step 4 - Deal with the Deceased

Check apparent deceased victims for signs of life

Identify anyone who may have already examined victims.

Coordinate the ME Investigators examination

Make note of any actions taken during these examinations (ME or EMS) that altered the body.

Step 5 - Photograph the Scene

Once “life-saving” or death verifying is complete, the scene is stable, with no further reason to violate or alter it.

Photograph the scene as it is, with both still and video. Concentrate on photographs that let the viewer see the overall context and conditions.

Chapter 6 describes in detail the photography process.

Step 6 - Document Overall Observations

Unlike the initial scan, this is an in-depth observation and description of the scene.

Requires a walk-through, but without altering anything, since sketching and mapping have not been completed.

Use an eight step descriptive set: quantity, item, color, type of construction, approximate size, identifying features, condition and location.

Step 7 - Sketch the Scene

Create a rough sketch of the scene that includes:– Room and openings with dimensions.

– Furniture with dimensions.

– Evidence items, with fixing measurements.

Support the actual sketch with written notes of measurements.

Chapter 7 describes this activity in detail.

Step 8 - Conduct a First Re-check

Up to this point all obvious evidence and scene features have been noted, photographed and sketched.

Visually re-check the scene to ensure that no items or critical observations were overlooked.

Step 9 - Release the Body

Release the body from the scene to appropriate authorities.

As it is moved examine the body, being sure to:– Document all surfaces before post incident bleeding

occurs. (e.g. bleeding in a body bag).

– Check the body with an ALS for easily dislodged hairs, fibers or other trace evidence.

– Preserve fragile evidence by bagging exposed hands or feet.

Step 10 - Collect the Evidence Collect all evidence items that were already located and

documented.

Examine each item for additional trace evidence.

If necessary take additional photographs to document close-up detail.

Ensure each item is documented fully on an evidence custody form.

Step 11 - Conduct a Second Recheck All known evidence has been safely containerized and

removed from the scene.

Second recheck involves far more intrusive actions including:– Checking surfaces with the ALS– Fingerprinting walls and other scene surfaces.– Exploratory searches and movement of furniture.

“Going back” is an integral part of the second recheck as new evidence may be discovered.

Step 12 - Conduct a Third Recheck

Verify no area was overlooked.

Recheck until rechecks are negative.

This a good time to review checklists.

Conduct extremely intrusive actions like chemical enhancements of floors, bullet trajectory analysis or bloodstain pattern analysis.

Step 13 - Check Beyond the Scene

Check the scene perimeter and outlying areas to ensure that no secondary scenes were overlooked.

Good time to follow blood trails, if present, using both visual and chemical (e.g. luminol) techniques.

Get exterior photographs of the area, building, and approaches to the scene.

Step 14 - Conduct an On-site Debriefing

Before releasing the scene, spend a few moments with the entire team reviewing and discussing the actions taken.

Make sure no assignments were forgotten or overlooked by the team.

Check individual documentation to ensure everyone is clear on directions and other scene aspects. This prevents later contradictions.

Step 15 - Release the Scene

Release the scene to an appropriate individual.

Do so only after you are confident that all activities are complete. The only way back is with an additional search warrant.

Remember, if you are unsure, it only takes manpower to hold a scene.

Step 16 - Process and Package All Evidence

On-scene collection may require temporary evidence containers.

Package all evidence for the long term as soon as practical, which may include drying of bloody objects.

Check evidence vouchers against scene documentation. If errors are noted, correct if possible and note any contradictions.

Step 17 - Conduct a Formal Debriefing

The debriefing should involve all available parties including the ME Investigator, initial responding officer, investigators and crime scene technicians.

Revisit basic information and actions taken.

This briefing helps eliminate investigative “red herrings” and focus investigative efforts.