Crime Scene Investigation
Chapter 3

This week we’re going to focus on the crime scene. This will cover chapters 3 and 4. There is a lot of information in these two chapters so we need to dive right in.

Chapter 3: Crime Scene Investigation
3.1 Crime Scene and Its Story
3.2 The Initial Crime Scene Investigation
3.3 Crime Scene Documentation, Measurement, and Imaging
3.4 Example Scene and Processing

The portions of chapter 3 covered include the initial crime scene investigation, documentation, measurement, and imaging, and then finally an example scene and how it was processed.

Defining the Crime Scene
What is the only thing consistent about crime scenes?

Answer: Variety

Every crime scene is different. It’s pretty safe to say there have never been two crime scenes that were ever exactly the same.

Defining the Crime Scene
Location According to Criminal Activity

Primary vs. Secondary
Size

Macro vs. Micro
Type

Homicide, Robbery, etc.
Condition

Organized vs. Disorganized
Physical Location

Indoors, Outdoors, Vehicle, etc.
Associated Criminal Behavior

Passive vs. Active

So, when we talk about crime scenes there are several definitions that we need to cover that can be used when discussing the scene.

Primary vs. Secondary: Some crime scene only occur in one area, but some may happen in multiple areas. An example of this may be if someone is murdered in one location (primary) and then the body is moved to another location (secondary).

Marco vs. Micro: Macro evidence (or photography) is anything that can be seen without the use of magnification, and micro evidence (or microphotography) is evidence that has to be seen with magnification.

Examples: Marco = victims clothing, bullet from the body

Micro = DNA evidence from clothing, stria on bullet seen under a microscope

Type of scene: Homicide, Robbery, etc. This is pretty self-explanatory; however, be thinking about the different types of evidence you may come across depending on what kind of scene you go to.

Organized vs. Disorganized: You can imagine that sometimes crime scene are messy (and that was before the crime was committed). Other times they are quite clean. Which kind do you think would be easier to process?

Physical Location: Crime scene may happen anywhere, in a house or commercial building, outside in a neighborhood, city, or the woods. It could also happen inside a vehicle. Basically anywhere that people are located.

Associated Criminal Behavior: passive is when a crime happens that wasn’t actually planned, where as active is criminal behavior where the criminal planned their activity.

Uses and Information from Physical Evidence

How do you determine pertinent
versus extraneous physical evidence?

Invaluable acquired skill and experience

Really, a lot of this comes with personal experience. Also, part of this can be trained, and some of this comes with instinct.

Uses and Information from Physical
Evidence

Linkage of persons, scenes, or objects
Locard’s Exchange Principle

Provide investigative leads
Direct and indirect leads

Information on the corpus delicti or modus operandi
Proving or disproving witness statements

Crime scene patterns or patterned physical evidence

So what does the evidence at a crime scene actually do to help solve an investigation:

1. It helps link people to the scene or to the victim.

3. It helps with investigative leads (what happened, whose the suspect, etc.)

3. Information on the corpus delicti (what crime occurred) or the modus operandi (the way the criminal worked)

4. It can also help prove or disprove witness statements. Witnesses are not always right.

Uses and Information from Physical Evidence
Suspect identification

Identification of unknown substances
White powder unknowns

Reconstruction of a crime
How vs. Who

So what do we do with the evidence that is collected from crime scenes? Well, I’m sure that if you’ve watch any TV at all then you would know that the evidence is analyzed and it helps tell the story of what happened and either help convict or exonerate a suspect in
the crime.

Uses and Information from Physical Evidence

What are the objectives of crime scene
investigation?

Recognize, collect, preserve, interpret

Objectives of Crime Scene Investigation

Recognize
Preserve
Collect

Goal of reconstructing likely chain of events that generated this evidence.

So if we break down what happens at a crime scene to just three words, it would be recognize, preserve, and collect.

Recognize: the CSI must first recognize what at the scene is evidence

Preserve: make sure that the evidence is preserved (photograph, document, and chain of custody)

Collect: collect the evidence in an appropriate way depending on what type of evidence is being collected

Pertinent Evidence at the Crime Scene

Crime Scene Investigator
Primary crime scene – ex. House

Macroscopic crime scene

Secondary scenes – ex. Burial site
Microscopic scenes

First Responder
Elimination samples

So when a crime scene investigator starts to gather the evidence at the scene he has to record the pertinent information. Such as the location of the scene, the part that it encompasses, and in this case any evidence that you need to collect from first responders to
eliminate it has evidence related to the suspect.

First Responding Officer
Who is considered a first responding officer?

Police officers, fire department personnel, or emergency medical personnel

First Responding Officer
Duties May Include:

Safety for themselves and the victim.
Render aid and assistance.

Assist the victim and prevent any changes to the victim.
Search for and arrest the suspect if that person is still on scene.

Detain any witnesses; do not take them back to the scene if at all possible.
Protect and secure the crime scene.

Document all movements, alterations, or changes made to the crime scene and pass this information to
crime scene investigators

So first responders are usually police officers responding to a call, but it could also include fire rescue or EMT. When an officer responds to a call they make sure that the scene is secure (safe) and then checks any victims to make sure that they don’t need an
ambulance. If they are already deceased, he will call the investigators/CSI to respond. Then they will detain any witnesses and start to make sure that the scene is secure from tampering and note what he did upon arrival.

Crime Scene Investigation
The Initial Crime Scene Investigation

Now we will focus and what happens once the crime scene investigator actually does when they arrive.

Crime Scene Survey
The “walk through”

First images and video taken.
Note any transient (temporary) or conditional (the result of an action)
evidence present and requires immediate protection or processing.

Be aware of the weather conditions.

Initially the CSI will do a walk though. During this, they will also talk to the first responder to hear all the information that they have. During the walk through the CSI will note any evidence that needs immediate collection due to the delicate nature of some types (such
as footwear impression that may be erase by people walking over them. Or possible DNA evidence that’s outside and it’s raining.

Crime Scene Survey

Note any points of entry or exit and paths of travel within the crime scene that
may require additional protection.

Record briefly initial observations of the answers to who, what, where, when,
and how questions.

Access the scene for personnel, precautions, or equipment that will be needed.
Notify superior officers or other agencies as required

All points of entry and exit are also noted. During the investigation, the initial point of entry (during the scene) is documented.

Sometimes there’s need to call in specialized personnel is cases that require special equipment or processing.

Documentation and Photography

Most important and time consuming activity at the scene.
Purpose: permanently record the condition of the crime

scene and its physical evidence.
Crime scenes are transitory and immediately begin to change.

Skills needed: problem solving, innovation, and originality.

Like the slide says, the most important and time consuming task at any crime scene is the documentation and photography of the scene and the evidence. This is to have a permanent record of the what the scene looked like at the time that first responders arrived.
It needs to be recorded as soon as possible due to the chance of evidence being lost.

Documentation and Photography

What are the major tasks of
documentation?

Note taking, videography, photography, and sketching

All four tasks are necessary and cannot act as a substitute for another.

Note Taking
Log of digital images

Observations
Rough sketch

Written record of all crime scene activities
Notification information

Arrival information
Scene description
Victim description
Crime scene team

Actions taken
Evidence identified

Listed above are some of the things that need to be recorded during the collection and documentation of evidence at a crime scene. Usually during an investigation people take different jobs in order the keep everything organized and efficient as possible. One
person will be taking the photographs, one for taking notes, and one to collect and package the evidence.

Digital Imaging & Video Recording
Digital Imaging

Captures and stores the record of the crime scene and its physical evidence for analysis.
Careful with image manipulation.

Video Recording (videography)
Document the recording by use of a placard.

Begin with the scene surroundings.
General orientation of the scene.

Victim’s viewpoint.
Original videos.

Most of the time the initial walk through includes a video of the crime scene prior to anything being collected. Now commonly digital photographs are taken at scenes and at the lab. When digital cameras first came out, the images were not easily accepted in court due to the belief that they images could be
easily manipulated (traditional film images can also be manipulated). Now images have a history associated with them.

Sketching
Final task

Units of measure/Correct perspective
Accurate measurements

Types of sketches:
Rough
Final

Perspectives:
Overhead/Bird’s eye view

Elevation/Side-view

After all the documentation and before all the evidence is collected, measurements are taken of the entire scene and of where the evidence is located. At the scene a rough sketch is done and then a final sketch is completed at the office, usually on a computer now.

The sketches and photographs can have different perspectives. Overhead, bird’s eye view, elevation view, or side view.

Sketching
Techniques:

Triangulation
Base-line

Polar coordinates

Fixed points
Survey markers

Large trees
Utility poles

Documentation
Title, Legend, etc.

When taking measurements of a scene, there are several options. You can use triangulation (this is probably the most common method used when measuring at a scene), it works for outdoors where there may not be too many points that can be used to
measurements from or inside a house using two corners of the room as the fixed points to measure from.

Anything method is base-line measurements. I’ve only seen this used inside buildings never outside.

I never seen polar coordinates used. This is most likely the least used out of the three methods.

When taking measurements a fixed point (that’s not likely to move) is used. This is usually trees, utility poles, or survey markers (for outside scenes) and corners of rooms or pillars (for inside scenes).

Of course to should always label your diagram with a title, legend, location, etc.

Crime Scene Mapping
Use of imaging technology

and GPS to create 3
dimensions for a forensic

map.

https://leica-geosystems.com/en-us/industries/public-safety/leica-geosystems-public-safety/public-safety/forensics

https://leica-geosystems.com/en-us/industries/public-safety/leica-geosystems-public-safety/public-safety/forensics

Over the last 10 years new technology has made a way for CSI personnel to record the entire scene (with laser measurements) using equipment and software such as the Leica Scan Station. This was first used in the department I worked for in South Florida for
vehicle homicide cases. The scanner was faster that people in recording the scene with measurements and could be used for reconstruction purposes later very easily. Also, since it was faster, roads being blocked due to an investigation were less frequent in
duration. When the crime scene unit (which was different from vehicular homicide) had a particularly large scene they would ask the other unit to borrow it until they received their own. The units were very expensive when they first came out on the market.

Here’s a video that show how it works https://www.youtube.com/watch?v=2SOLrtlUA_I

Crime Scene Searches

Should documentation be done before
or after evidence collection?

Documentation must be done before any evidence is moved or collected

Crime Scene Searches
Should be conducted after documentation and prior to collection

Search Patterns
Link, line, grid, zone, wheel, spiral, or combination

Aid of field testing, visualization and enhancement reagents
Restriction of searchers and collectors

So before any evidence is actually collected, it has to be searched for. In a inclosed space, such as a house, this may be a straight forward operation. If it’s outside however, it may be a lot more difficult. There are many way to search the scene for evidence and your
book gives several examples. Please read up on the different methods of searching for the quiz.

Sometimes the CSI may need chemical or physical enhancement in order to visualize the evidence. Some examples of this may be fingerprint powder or other chemicals used to visualize latent prints, or luminol to visualize blood that the suspect may have attempted
to clean up.

Chain of Custody
Insert Figure 3.9

Chain of custody is very important to an investigation. If the evidence that’s collected doesn’t have a proper chain of custody then it will not be admissible into court. The chain of custody records where and when the evidence is collected as well has by who. Then
each person that has custody of the evidence records their name date and time of when the had the evidence. This creates an unbroken “chain” so that the location of the evidence from the times it’s collected is always known.

Crime Scene Reconstruction
Determining or eliminating events

Involves:
Interpretation of evidence

Laboratory testing
Systematic study of information

Logical formulation of potential scenarios

Crime scene reconstruction can be used to compare stories to evidence and evaluate different versions of events. One of the advantages of laser scanner which was mentioned a few slides earlier is that is makes reconstruction of the scene a lot easier since all the
necessary data is already stored in the computer.

Crime Scene Reconstruction

Reconstructions can be done with physical reconstruction (using real people or dummies) or digital reconstruction (using a computer). The benefit of digital reconstruction is that it can be viewed from all angles once a scene is frozen and even introduce firearm
trajectories based upon suspect victim positions and wound angles.

Collection and Preservation

How are Different Types of Evidence Collected and Packaged?

Each item of evidence should be packaged separately to prevent cross contamination between items of evidence. Collection and packaging depends on the type of evidence and will be discussed further in future chapters.

Collection and Preservation
One evidence collector

Ensures consistency

Priority:
Transient, fragile, easily lost

Dependent on type of evidence
Liquid or volatile

Biological, wet, or moist

Importance of collecting controls

Like I stated in a previous slide, usually one person is assigned the task of evidence collection. This ensures that everything is collected consistently and makes chain of custody straightforward. The evidence with the greatest chance of being destroyed is collected
first. Also, each type of evidence has it’s own correct way of being collected. We will get into the specifics of the proper evidence collection with each chapter that we discuss throughout the semester.

Collection and Preservation

• Primary and secondary containers
• Sealed
•Completely cover opening
• Initialed

• Labeled
•Collector and date/time/location

One thing though with evidence collection that is universal is that there is usually (there are some exceptions) a primary container (inner package) and a secondary container (outer package). The secondary or outer package will be sealed, meaning it will have
tamperproof tape applied to the openings of the package and the person that collected the evidence initials written across the seal. This will prevent anyone from opening the package that is not authorized. Each time the package is opened (in a different area) it will
be by someone that is on the chain of custody (and has custody at time of opening) and that person will sealed the package up where they opened it and also initial over there tamper proof tape. The chain of custody will have the persons name and at least the date
and time of receiving the item. Most agencies now do this electronically; however, when I first started forensics nearly 20 years ago, it was still maintained on property receipt and you have to sign for everything with a handwritten signature. It was a lot of writing!

Chapter 3 Summary

Materials -> Evidence
Evidence requires context.

Provided by documentation; photography and videography and supported by sketches
and notes.

All elements combine to process a scene.

For the next chapter we will be focussing on a specialized portion of the crime scene (blood spatter evidence) and an overview of how that type of evidence is processed and what it can tell investigator about what happened.