Searching the Scene:
Logic in Action
Collecting evidence without a
valid reason is also stupidity in action.
Searching: A Philosophy
The crime scene
The place where individuals participated in an event at a
point in time that resulted in the creation of evidence
Finding this evidence that links the participants to the scene is
why crime scene investigations exist and why searching is critical.
Scene Type Examples
 Hit and run cases:
 Two cars - one hitting the other – one
leaves the scene.
 A single car hitting a pedestrian and
leaving the scene.
 Sexual battery case:
 Assailant breaks into apartment or house
 Assailant abducts the victim off the street.
2. Homicide cases:
 Violent dispute between spouses,
 A shooting in a drug case
The crime might not define precisely
the types of evidence present.
BUT
Scene scientist/investigators
understand that certain crime types
spawn specific types of evidence.
Archiving and Searching
Common Scene Types
 Crime types …
 Investigators need to understand the nuances of each.
 Each crime scene is unique and each presents challenges
different from the so-called norm
 Different crime types present overlapping categories of evidence
because,

What starts as a burglary may become a homicide or a sexual
assault.
 Specific attributes will occur more frequently with a particular crime type,
 Semen in sexual assault cases.
 The forensic archivist’s responsibility is to capture the scene
photographically or by sketching which should ultimately lead to evidence,
which is collected.
 During the archiving process, the investigator who “finds” evidence
should alert search team and team leader.
Evidence in Selected Case Types
• Vehicle searches
– Hit & run
• Exterior/undercarriages/grill/headlights/bumper/windshield
• Injuries to victim & operator of the vehicle
– Tissue/blood on vehicle
•
•
•
•
•
Fingerprints – outside & inside
Paint transfers – on clothing, to vehicle
Fabric pattern transfers – to vehicle
Trace evidence transfer – glass, hairs, fibers
Blood, blood spatter
• Homicides & Sexual assaults
•
•
•
•
•
•
•
Interior for blood/semen/trace evidence
Blood and blood spatter
GSR/Bullet path determination
Fingerprints
Trace evidence
Saliva
Vehicles often involved
• Suicide
•
•
•
•
Blood spatter/bullet path determination
GSR
Notes / family history
Scene characteristics
Processing Or Investigation?
 Scene investigation is NOT a blind endeavor
 Scene investigations are extremely complex
 Searching is crux of the investigation
 Many believe searching the scene is a simple, thoughtless process that
anyone can perform.
 Certainly archiving is important, for if done badly, anyone
examining the scene after the fact will not “see” the original scene.
 Poor approach to searching leads to second guessing,
 If search is conducted logically and systematically, it will be
comprehensive and result in success
 Police agencies often call it “processing the scene.
 The term screams simplicity
 Exercise requiring minimal thought to what is being done or why.
 Definition of investigation is more rigorous and appropriate. “Processing”
should be replaced with something that projects cognizant thought, such as
investigation.
Processing Or Investigation?
“Processing the scene,”
Modern texts lull students, novice investigators and seasoned
investigators into believing that scene searching is a simple process.
Process:
“a series of actions or operations conducing to an end; especially : a continuous
operation or treatment especially in manufacture”
Processing is mindless activity and simplicity in action. The term should
be replaced with something that projects cognizant thought,
Investigation;
“
Scene investigation and searching is more than a “process.”
It is a scientific endeavor and investigation, and
certainly more than a simple "process."
What is the Scene Search?
 Three components
 The Intellectual aspect –
 The Crime Scene Investigative Cascade
 The logic to devise a strategy for the search
 On-scene activities.
 Byproduct of two activities:
 Original walk through with the first officer
 Archiving.
Why the Walk-Through?
 An aspect of scene management
 Team leader observes and absorbs the
macroscene elements during the walk-through
 Gathers information about the scope, size, and
location of obvious evidence
 Devises an initial search strategy
 Recognizes immediate fragile evidence
 Need to protect this evidence
Why Archiving?
Archiving gives the only pictorial perspective
 Illustrates how macroscene elements relate to
each other.
 Shows the relative location of evidence
 Its interrelatedness becomes obvious.
 As such it shows the location and relatedness of
obvious macroscene evidence
 If the archivists and team leader are in synch,
information emerges from the chaos that is the
hallmark of all crime scenes.
What About Searching?
 An integral arm of scene management and
archiving.
 The team leader and the team design
search strategy based on logic
 Not on a "method" published in a text
book.
o Proper search requires
understanding of the scene.
 Mental and physical activities are inextricably
joined,
 If scene management is the glue that holds
the investigation together,
 Scene search is the meat and potatoes
of the investigation.
The Scene Search
Logic in Action
The Meat and Potatoes
Scene
Management
The Investigative Glue
Archiving
(Video/Photo/Sketch)
Eye for the Future
Defining the Search
Defining the Search
 Assume investigative team has legal right to
investigate
 If so, then the crime scene search begins when
the team leader walks through the scene for the first
time with the first or responding officer.
 Team leader “sizes up” or takes inventory of
the scene and assimilates first impressions.
 Initial investigative strategy and
precautions take shape,
 Macroscene elements and other scene
nuances absorbed.
Immediate Concerns
Macroscene Elements
Other Issues
Size – physical terms
Obstacles
Relevant – Obvious Evidence
Additional Resources Required
Fragile Evidence
Media
Scope – Crime Type
Primary/secondary/staged
Command Center/Containment
Modern Considerations
 Modern crime scene investigation texts consider the scene
search as a methodical process and often presented as a
“method.”
 They promulgate “named” procedures designed for specific
crime scene types, such as for indoor and/or outdoor scenes.
Such a simplistic approach is ridiculous.
 Intent of “methods” is not to convey simplicity
 Present inexperienced and experienced investigators a
roadmap so they can avoid making serious mistakes, such
as missing important evidence.
 Minimizing errors is better accomplished in another way.
Successful Searches
General Guidelines
Attributes of a Successful Search
Elements
Effective Management
Experience – knowledge – leadership
Understanding the nature of the Scene
Size, scope, weather, obstacles, on-scene
environment, lighting, etc.
Appropriate Logic
Employing the scientific method
Systematic approach
Not random
Creative thinking
Relative associations of scene elements
Effective Management
 Minus a strong, experienced manger, scene
searches and the entire investigation will be chaotic and
doomed to fail.
 A strong leader keeps team focused,
 Assigns roles when required and
 Keeps the investigation on track.
 Novice investigators and some seasoned
investigators tend toward random searches without
rhyme or reason except to “follow their nose.”
 Effectively managed teams are efficient and
thorough.
Indoor Crime Scenes
 Each scene is different. Homicides in large cities often occur in
apartments…. Seemingly similar circumstances … they are not.
 Different geography, clutter, etc.
 Some might be air conditioned and comfortable in the summer
 Others may stiflingly hot, sticky and uncomfortable.
 Differences in temperature and humidity make can dramatically affect the
success and efficiency of the investigation.
 A scene in the middle of July when the temperature is 97oF and the
humidity 92%, unpleasant odors, such as coming from a decomposing
body, can be oppressive.
 Air conditioning makes oppressive odor more manageable. In the scene
that is not air condition, the odors are overwhelming. At the latter scene,
excessive perspiring makes investigators to work unintentionally faster …
can flaw the investigation.
Outdoor Crime Scenes
 Huge environmental obstacles … affect the investigation. A
scene in the woods differs from a shooting in a parking lot.
 Scene in the mountains in the middle of winter with the
temperature hovering in the 20oF range and after a snow
storm has obstacles different than the same scene in the
spring with the temperature in the 60’s.
A field of corn in May is different than the same field in late
July.
 The landscaped back yard of a residential house is
different from an un-mowed field of knee high wheat.
Each has obstacles and each requires a strategy born from
logic … to search correctly and efficiently.
Searching With Purpose
Systematic Search
 Gardner suggests that a crime scene search should be
methodical and systematic, and defines systematic as
“purposefully regular”. …
 Military & paramilitary agencies easy to implement … gives
police/military investigators a way to standardize the search to
accomplish a specific goal.
 Accountability easier to control,…
 Standardization gives the appearance of thoroughness.
 In fact, the opposite may be the case.
Method vs. Logical Searches
 Method searches: A way to do something that is rote,
repeatable and efficient.
 Lead to thoughtless searches
 Repeated at scene investigations throughout the U.S.
 Immortalized in crime scene texts.
 Logical Searches
 Minimizes missed evidence
 Minimizes collection of evidence that is not relevant
 Rather than just methodical and systematic, the crime
scene search should be logical (reasoned) and systematic.
Logic Means
Using reasoning to recognize
relevant evidence.
A Reasoned Approach
 Scene search should be guided by the question of
relevance, … refers to the relevant investigative questions.
 Relevant investigative evidence leads to probative
evidence
 Answering these investigative questions determines how
the search is conducted.
 Inman and Rudin said, “searching is looking with purpose”,
This is not a method approach.
It is a reasoned approach.
Innovative or Creative Searching
 The most successful scene detectives and
criminalists are innovative
 Have an innate ability to think creatively.
 Skill some learn or approximate over time
through experience.
 However, some “see” connections where
others, even experienced investigators, do not.
 Those possessing this ability are the best crime
scene investigators.
Named Search Methods
Scene Search Methods
 Typically presented as methods of choice in crime scene textbooks, …
 Logic can replace all of them …
 A certain aspect of truth with many.
 Investigators have had success searching scenes … if had been a flop,
there would be no reason for passing formats … workshops, training
exercises or written format.
 Method searches for indoor and outdoor scenes designed for
specific situations … scene investigator decides which to use.
 Thus looking for human remains in a public park and wooded area
outside Washington DC might requires a different search strategy
than that used to find fragments and body parts from an airplane,
such as flight 93 that crashed in Pennsylvania on 9/11.
Minimizing mistakes
 Searching a wooded area … trees and shrubs offer challenges
 Maintaining search line properly
 Requires a logical and systematic process that milling around,
for example, cannot deliver.
 Searching an open field has no obstacles & are not restricting.
 A proper search requires understanding what the scene is saying.
 To many investigators, searching (an area), whether inside or outside,
isn’t as sexy as other scene-related activities
 Bloodstain pattern analysis, enhancing tire track impressions or
dusting and lifting fingerprints.
 Searching is sexy … if the team in synch with the scene, searching will
suddenly rear its head and give that “Ah ha!” moment when something
important is located, such as the evidence that will lead to a successful
prosecution or the exoneration of a suspect.
A logical and systematic search
Best way to find objective evidence for court.
 If haphazard or random, the risk is missing important evidence or, equally
important, incorrectly assessing the scene correctly - finding a motive, linking
evidence, interpreting the sequence of events, and etc.
 Searching … ability to use their hands and powers of observation
 Tendencies for bias, attention to detail and experience are on display.
 Searching is one of the more critical functions of an investigation, Does critical
adequately describe importance of scene search?
The Merriam Webster Online Dictionary defines critical “
1: of, relating to, or being a turning point of an important juncture.” Doesn’t this
completely identify with the importance of the scene search.
When the search begins, the team enters a make or break point of the
investigation because this is when it is looking to “make” the case.
Basic “Method” Search Patterns
• The “Method” Approach – Grid
– Strip/Line
– Circle/Spiral
– Ray
– Zone
– Link
– Point-to-point
Milling around
An Un-method
Not systematic
Not logical
Not appropriate for any scene
The Line (Grid)
Methods
 Diagrams of Grid/Line searches are
self explanatory,
 Little to need to explain the
mechanism of how a search of this
type might take place.
 All “method” searches are roadmaps
…
 If followed correctly, the search
will likely be conducted properly.
 The grid is a two-step variant of
simpler search types, which are
conducted in typically one direction.
Line Searches:
 Unidirectional line searches lead to
missed evidence,
 Complicated areas where
evidence may be difficult to see,
e.g., woods, fields, etc.
 On flat, uncovered surfaces that are
small,
 Concrete and paved parking lots
where the line-of-sight is
unhindered, these methods can be
appropriate.
 Nothing is lost, except time, by
performing a perpendicular search - as
in a grid.
 Underwater searches
Water Line Search
Line (strip) Methods
 Team Leader coordinates
search
 Mostly applicable to
outdoor scenes
 Useful for a few or a large
number of searchers
 May use untrained searchers
 No boundaries make it
difficult to search
systematically
 Large areas
o
o
o
o
o
Parks
Yards
Parking lots
Highways
fields
Start
End
Line (Strip) Methods
Continued
Depending on the nature of
the scene,
Can mark-off or delineate
lines/lanes searched
 Ensure full coverage.
Divide the area into strips or
lanes (north/south or
east/west).
Assign teams to line up
shoulder-to-shoulder
(typically an arm’s length
apart.
 nature of the evidence
dictates the separation
between searchers at the
start of a strip or lane.
 Plane crash in a field
 Body dumped in the
woods
Start
End
Parallel Search
Designed for
smaller outdoor
scenes.
Drawback of
parallel & any onetime search
High possibility of
missing evidence.
Finish
Start
Grid Method - Modified Line
 Modified double-line
search
 Searches area twice
 Two different
searches cover same
area
 Two eyes are better
than one
End
 Two lines created
perpendicular to
each other
 Follow first line &
search as in Line
Method
 Re-search @ right
angles in the
second line search
Start
Grid Searches
 The grid search … most appropriate variation of line/grid searches for
outdoor environments … applicable to all environments.
 Line search is variation of grid search,
 Single-pass search
o NEVER appropriate, because it misses evidence.
 For large outdoor scenes, such as an airplane crash, it may be appropriate
to grid the scene and then conduct individual grid searches within each major
grid.
 An example was the WTC scene after the 2001 attacks on the World
Trade Center buildings.
 The scene was gridded into 70 foot squares and each grid searched
systematically.
That scene was different than most because each grid had 3D
characteristics, surface and depth.
The Sequence of Outdoor Grid Search




Photography
Establish scene boundaries
Identify an appropriate search method.
Searchers are at arm’s length distance apart in a line
 Walk in straight line until an item of evidence found.
 Line stops … mark evidence with evidence marker flag
 Line continues until the search has been conducted.
 Line turns and searches in perpendicular direction to give the scene a
duplicate search. Individual searchers never search the same area twice.
 Midrange photography of marked evidence
 Close-up photography of marked evidence
 Sketch the area, measuring and pinpointing evidence locations
 Collect and package marked evidence
 Transport the packaged evidence to the police department and/or crime
laboratory
Zone and Point-to-Point Searches
Appropriate for Indoor Scenes.
Zone Method:
 A way to prioritize search areas, such as rooms in a house. Each
room is a zone, and the attention it receives depends on scene
circumstances.
 Areas of most obvious activity are primary search areas. The zone
where the body was found and the entrance and exit paths are prime
search areas.
 A bedroom that apparently had no activity might not seem as
important,
 Should be some discussion concerning whether it might have
probative evidence and how much effort should go into searching
it. In truth, no area of the scene should be ignored.
Zone Search
Bthrm
Zone C
• Scenes with readily
definable Zones
• Search each zone @
least 2x
• Variety of alternatives
to this approach
Bedroom
Zone E
Bedroom
Zone D
Dining Room
Zone D
Patio
F
Kitchen/Living
Room
Zone A
Foyer
Zone B
Walkway to
Main Entrance
Zone F
– Each zone searched
systematically
– Indoor scenes
• Zones can be
subdivided
• Zones can be
prioritized
Macroscene Elements
1.
2.
3.
4.
Body in Bedroom B
Bloodstains in Kitchen & Bathroom
Dust footwear impressions in Foyer
Broken window at front door
– Location of body
– Entrance points/exits
– Other targeted areas
Point-to-point Search
 Small, confined areas and when a
potential route of travel has been
detected or is suspected.
 Identify key locations or areas within
the crime scene
 Points of entry/exit, location of the
victim, location of weapons, etc.
A
 Thoroughly examine the pathways or
routes
 Connect the key locations to other
areas where evidence may be found.
 Fragile evidence
D
B
 Evidence on the floor,
 Footwear impressions, trace evidence, etc.
and make every effort to avoid altering or
destroying the evidence
 Maintain a narrow path into and out
of the scene.
C
 Be cognizant of fragile evidence
 Search each area by at least two
investigators
 In pairs & one after the other.
Movement through scene
Divided by quadrants
Link Method
Thinking the Search
Footprint
 Not geometric,
 Not easily definable or
random
 Exploits 4-way linkage theory
 Finds associations among




Scene
Victim
Suspect
Evidence



Footwear & tire impressions along
adjacent, logical pathways
Things missing from body
Consider secondary/staged scenes
Sexual Assault

 Logically systematic
 Evidence associated with obvious
activity
 Each step based on findings &
observations & applying logical
progression
 Expectation that evidence will be in
“that” location
Fingerprint
Homicide Example


Window



Evidence Types
 Semen
 DNA
 Bite marks
Amount & pattern of blood
Weapons
Fingerprints/DNA
Wheel / Ray
In a large area this method is a recipe for failure.
Essentially a circular
search
 Start @ critical point
 Travel outward along
straight lines (rays)
Difficult for searching
large areas
 Used only for special
situations w/limited
applications
Spiral Search Patterns
Spiral search:
 Investigator begins at the epicentre of
the room and moves outwards in a spiral
pattern.
 Alternatively the investigator starts at
the edge of the scene and spirals into the
centre.
Employing On-scene Technology
and/or Statements
 Logic in action also means taking advantage of everything available to
narrow the search area.
 Using Technology: burglar caught on a surveillance camera …captured
path through scene and areas touched.
 Dramatically narrows search area … know how the burglar got
inside the premise, movements, and what touched.
 Areas not captured by the video must be searched.
 Statements by witnesses and/or victims can also help narrow the
search area.
 If the victim of robbery tells investigators that the robber was not in
certain areas of his store, searching them is waste of time.
 Archiving still necessary.
Pressure at the Scene
Exist on a multitude of levels
 Media exerts own brand of pressure, such as hounding the team leader
for information.
 Team leader tied up with detectives … places a burden on team
members.
 Team size creates other pressures … small team may work well
together … members have more work than those in a larger team. This
creates a situation where rushing can create errors. This is a pressure with
which the team leader must deal carefully.
 Demanding superiors – police chief, the Mayor, etc. - create pressure to
speed search and provide investigative information.
 Environmental insults create pressures on outdoor scenes …
destruction of evidence.
 Political pressure @ new levels in high profile cases, e.g., police
shootings, deaths of well-known individual and cases of bias.
Constraints
Scenes have constraints … time.
 Multiple constraints:
 Workload, where the investigating unit has other scenes
to investigate,
 Weather
 Geography
 An example might be a fatal hit-and-run on a major
thoroughfare during in rush hour, where there is not only
time but other constraints: traffic, pedestrians, etc.
Locating Trace Evidence at the Scene
Areas of Macroscene Elements
Knowing where to look.
Not difficult, but can be elusive without a
clear understanding of the scene characteristics.
Location
Points of entrance and egress
Areas of a struggle
The clothing and shoes of participants in the crime
(victims and suspects)
Furniture - understanding the transfer potential of
certain fabrics
Bodies of decedents
Fingernails
Areas searched by perpetrator
Reason
These are areas where the perpetrators might have
been and can be locations of fibers, hairs, etc.
These areas are prime targets for hairs fibers, blood
and saliva. They include furniture and carpets and
should not be overlooked.
The clothing of victims and suspects in direct contact
with each other should have fiber, hair, saliva, and
blood evidence present.
Fabric furniture involved in a struggle (turned over
chairs, etc) has the potential of attracting fibers and
hairs. The likelihood depends on the characteristics of
the fabric – whether it accepts and/or gives up its
fibers readily. These can also have saliva and blood.
The body, its clothing.
Anyone involved in a struggle has the possibility of
having trace evidence under the fingernails: hairs,
fibers, saliva and blood.
If a perpetrator, e.g., a burglar, is searching for
valuables, the areas searched are prime targets for
trace evidence.
Technology to Aid Searching
Most search activity employs a visual examination of the scene. The wavelengths on ALS can
help locate specific types of evidence.
 Searching for Trace Evidence – Overview Considerations
 A scene search does not end with picking up items only elements of the
macroscene.
 Also consider the invisible evidence. ALS helps locate invisible evidence, e.g.,
UV light (300-400 nm) aids in finding hairs and fibers and light at 450 nm will
help locate fibers and some biological evidence.
 Collecting trace evidence is critically important. Since it is mostly invisible to
the naked and aided eye, collecting requires logical thought process of knowing
where to look and then using standard techniques for collecting it.
 Knowing where to look can be elusive if there is not a clear understanding of
the scene characteristics: Logic in action.
Suffice to say, each scene represents a unique challenge.
Using the ALS to Locate Evidence
Wavelength (nm)
Application
Goggles
White Light
General scene scanning
Fingerprints on shiny surfaces
Blood on shiny and dark surfaces
Long Wave
UV
300-400
Hair, fibers, fluorescent materialpowders
Body fluids/bruises/bite marks/
Food stains (tomato based fluoresce)
Clear or Yellow
415
Bloodstains (absorbed :appears dark)
Food stains (tomato based)
Clear
450
General scene scanning for Body Fluids,
semen blood
Powders/Teeth/Bones
Paint/fibers/accelerants
Orange
465-485
Fluorescent materials/powders
Body fluids
Orange
515-535
Super glue fumed fingerprints
Body fluids
Red
(Clear for body fluids)
570
Inks
Clear
Red
Collecting Too Much Evidence
Tape lifts of trace material from furniture in a living room, a conversation might
go something like this; this could be a phone conversation or could take face-to-face.
Understand that a phone conversation like this might take place days or weeks after
the evidence had been submitted to the laboratory.
How Much Evidence to Collect
Scientist:
Investigator:
Scientist:
Investigator:
Scientist:
Investigator:
Scientist:
Investigator:
Scientist:
Investigator:
Scientist:
Investigator:
“You sent 175 tape lifts from furniture taken from the Dracula scene. I gotta tell ya,
there’s no way I do all that work in my lifetime. Why so many?”
“I took what I thought was important for the investigation.”
“I understand (thinking the investigator is doing CYA), but is there some priority
here?”
“They were in the room where the murder took place.”
“Hmm … Each piece of furniture has a an evidence item number. Evidence was
collected from 10 pieces of furniture. Were they all directly involved in the struggle?
Lemme check the scene photos.
OK.
The struggle mostly took place in one area of the living room, probably on the sofa,
Item number 4.
OK. I’ll start there. What else?
A chair near the sofa had been knocked over. It, too, might be a possible. Item
number 7.
Thanks, I’ll look at both of them. I’ll let you know what I find, and we can decide
where to go from there.
OK, sounds good.