Chapter 2

Protective Clothing Worn at the Crime Scene

Coveralls/ jumpsuits worn over clothing Removed afterwards and searched for

evidence before throwing away. Surgical gloves are worn the entire

time on the scene Masks and hair nets are worn most of

the time to protect from contamination Booties are worn over shoes to prevent

evidence from being contaminated

Primary Crime Scene- Where the crime actually occurred

Secondary Crime Scene- In some way related to the primary scene, but not where the crime occurred (i.e. body dump, getaway car, hideout)

Search Patterns- Spiral

Start on the inside and work your way in or vise versa.

Start at one edge and make a line up and down throughout the entire search area.

Search Patterns- Strip/Line

Search Pattern- Grid

Complete a strip/line search and begin a search in perpendicular rows to the already searched areas.

Search Patterns- Quadrant

Break up the area into small search areas and individuals search their own quadrant before moving on the next.

5 Steps to Processing a Crime Scene

Interview Examine Photograph Sketch Process

Step 1: Interview Begins once the Crime Scene

Investigator arrives at the scene The first responding officer makes

sure there is no longer a threat, he/she assists any victims, then preserves the crime scene.

The first responding officer is interviewed as well as any victims and witnesses

Step 1…Continued The FR should try to detain the person

who made the report. (He/she does not know if they are a witness or a suspect.) Others on the scene may also need to be detained

He/she must create a “security log” of who is going in and out.

This helps the CSI form a theory of what may have happened and potential evidence to look for

Step 2: Examine

Examine the scene to see if the theory he/she thinks is what the evidence shows

The CSI looks for potential evidence that would be beneficial to the case as well as a point of entry and exit to the scene

Step 3: Photograph

Photographs taken to give an overall view of the scene

2 Categories of photos: Overall views- zoomed out, full

room views Items of evidence- pictures of

evidence photographed with a scale

Step 3: Photograph

35mm cameras are still used for pictures

Tripods can be used when taking close ups or many pics in one area

Digital photos can be easily altered, so they are not used as much

Details of evidence and position

Camera setting Time, date,

location Photographer taking the picture

Documentation of Photograph

Step 4: Sketch Sketching the crime scene is a way to

pictorially show where things were found once you leave the scene.

Must create a “rough sketch” while at the scene. Measure all items , furniture, and room

dimensions Measurements should be made from

fixed points The rough sketch is kept with the

investigators notes

Step 4: Sketches

Final sketches are sometimes made for use in court. Must be drawn to scale with a legend All evidence including the body is

shown and measurements from fixed points are shown

Step 5: Process

Processing the scene means to search and obtain all of the evidence from the scene.

2 forms of evidence collected Testimonial evidence form witnesses Physical evidence which is tangible

Types of Evidence Physical Evidence- nonliving or

inorganic (fibers, paint, drugs, bullets, …etc.)

Biological Evidence- organic (blood, saliva, hair…etc.)

Reconstructive Evidence- any evidence that helps law enforcement gain a better understanding of what happened at a crime scene (broken glass, pried-opened doors/windows, trajectory of bullets) Determines who did what, where, when

and how

Types of Evidence

Associative Evidence- ties a suspect to the crime scene (could also disprove) Could be a fingerprint, hair,

shoeprint, blood…ect.

Collecting Evidence

Each type of evidence may have a specific way to be collected and packaged

Fibers and Hairs Use forceps to collect Collect items of clothing from suspects

and victims and bag Collect vacuum sweepings from each

room and package separately

Collecting Evidence

Fingernail scrapings Collect with a dull pick much like a

toothpick Put all of the scrapings into a bag labeled

with location, date, time, case number and person collecting the sample.

Collecting Evidence from a Victim

Autopsies are performed on deceased victims

Evidence such as the following must be collected: Clothing Fingernail scrapings Blood DNA

Collecting Evidence from a Victim

Once a body is buried getting evidence off of it takes time and has to go through the court system (exhumation)

As a medical examiner, you must get all of the evidence off of the body before burial or risk losing it

Evidence Collection

Each piece of evidence must be placed in a separate bag or container and labeled with Date, Time, Location

and Collector

Evidence Collection

Biological samples that are susceptible to bacterial or fungal contamination should not be kept in an air-tight container Blood Semen….etc

Chain of Custody

A list of all persons who come in contact or possession of an item of evidence

Used in court to account for the where-abouts of evidence since collection

Evidence must be properly labeled and a chain of custody record must be kept

Standard/Reference Samples

Physical evidence whose origin is known such as blood, hair, glass or soil from a suspect that can be compared to crime scene evidence

Examples: Soil samples from all types of soil around the

crime scene Blood samples from the victim and the

suspect Samples of all medications found at the scene Hair samples of all persons at the scene

Substrate Control

Uncontaminated surface material close to an area where physical evidence has been deposited Glass samples Hair Soil Blood

Example of Control Sample A sample of charred carpet is thought to

have accelerant residue on it. It is compared to the same kind of carpet known to be free of the suspected materials. A carpet sample taken from an undamaged section of fire may provide the known sample. If a suspicious chemical is present in the charred carpet but not in the known sample, the lab can be more certain that there is a foreign chemical involved and not a component of the carpet or adhesive.

Individual vs. Class Class Characteristics

Properties not unique to a particular object, but place it into a particular group. .38 caliber gun, type B blood

Individual Characteristics Properties of an object that narrows down

the evidence to one person or a very small group of individuals Fingerprint on a .38 caliber gun, DNA of the

type B person

http://www.fws.gov/lab/csi_evidence.php

Direct vs. Circumstantial Evidence

Direct- establishes a fact (eyewitness statement, confessions), not as reliable b/c an eyewitness can be wrong

Circumstantial- requires that a judge and/or jury make an indirect judgment/inference about what happened (evidence identified through forensic science), more reliable

Recognizing a Staged Crime Scene

Most common- making a murder look like a suicide or accident (suspect may move the body or cleanup certain areas) Example: A husband strikes his wife on

the head with a blunt object, killing her. He cleans up the bedroom, moves her to the bathroom and puts her in the tub. He calls the paramedics and claims she fell while bathing.

Searching without a Warrant

1. In an emergency situation- a second entry at a later time would require a warrant.

2. Impending loss of evidence- for example, if a fire were going to destroy evidence.

3. Lawful arrest- the suspect and their property may be searched.

4. Consented search- the person has given permission.

Obtaining a Search Warrant

Must be specific about the time, place and items and must have probable cause approved by a judge

Only a law enforcement officer may obtain a warrant

Steps to Obtain a Warrant Prepare an affidavit- must describe

location to be searched, items to be looked for and the reason why the officer thinks they are there

Prepare warrant- this results in the document the judge must sign giving permission for the search to take place

Get the warrant signed- the officer must present the warrant and affidavit to the judge. If the judge agrees that probable cause exists, he/she will sign making the warrant official

Linking Criminals & Crime Scenes

NCAVC- National Center for the Analysis of Violent Crimes (throughout the country) This led to the development of VICAP (Violent

Criminal Apprehension Program) and PROFILER, which maintain profiles of serial murderers.

Data from crime scenes are entered into these databases. Investigators can take current cases and create profiles and compare it to those in the current database with the hopes of linking crimes & catching a perpetrator.