1. Practical Crime Scene Processing
and Investigation
Greg Dagnan
Chapter 4 - Processing Methodology

2. 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.

3. 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.

4. 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.

5. Basic Activities of Crime Scene
Processing
These six activities and their basic order are:
– Assessing
– Observing
– Documenting
– Searching
– Collecting
– Analyzing

6. 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.

7. 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.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

13. 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.

14. 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.

15. 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.

16. 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.

17. 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.

18. 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.

19. 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.

20. 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.

21. 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.

22. 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.

23. 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.

24. 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.

25. 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.

26. 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.

27. 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.

28. 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.

29. 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.

30. 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.

31. 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.

32. 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.

33. 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.

34. 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.

35. 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.

36. 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.

37. 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.

38. 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.