Crime scene investigation final

Establishing a Path of Contamination is when

Police, EMS and fire personnel are trained to sensibly enter crime scenes so that they follow a safe corridor which is where the least evidence is disturbed.

Causation

Many crimes include an element of harm and that a relationship exists between the act and the result. This basic legal premise is called

The Locard’s Exchange Principal

States that with contact between two items, there will be an exchange of material- this is also known as gross.

It is said that the best evidence is

The suspects’ fingerprints made with the victim’s blood. A bloody print is an example of which type of fingerprint a patent print . A latent print is the veritably invisible print left from a subject. Patent fingerprints are easily visible to the human eye. A plastic print is when it's in soft material. They are left behind when blood, ink, paints, , grease or dirt is transferred from a finger to a surface.

When determining potential scenes for investigative purposes for a crime of interpersonal violence

The victim's body is treated as it's own, separate scene.

After the photo placard photograph

the next series of initial photographs taken should be the overview photographs.

In Close up photograph’s the proper use of scales allow for a

1:1 ratio reproduction of the photograph and facilitates analysis

A Final Sketch should include ALL items on a photo placard plus

a legend and scale

Before any evidence is collected

an investigator must decide if there is legal standing to be on scene. If a search warrant is required and if any case law pertinent to the incident. ( can be an all of the above question)

The Plus one officer safety theory

is applicable to crime scene investigations

A criminalist considered tier of investigation

will analyze and interpret the evidence

A detective is not considered a first responder

But a Police Officer, firefighters and Medical personnel EMS are types of first responders

The definition of evidence

is all the means by which a matter of fact submitted for evaluation can be proved or disproved

Crime scene “don’ts”

include eating at the scene, using the bathroom and using items on scene such as televisions, stoves etc

After determining safety

the next primary duty of the first first responder is to secure the scene and not touch anything. Always start larger as the scope of the scene is more easily reduced

To limit potential loss of evidence

a Crime scene technician should establish and follow a Path of Contamination. Also, they should limit access to the scene and wear Personal Protection Equipment (PPE).

A Final Sketch will not

show measurements but can/will be used in court and will have a legend.

The steps taken upon request to respond to a Crime Scene:

_Ask is it 8 heads in a duffel bag

Start Notes.

Respond.

Get debriefed

Determine legal authority to be on the scene.

Conduct the walk through-formulate the plane (Charlie Brown detective)

Document the scene notes sketch

Photograph the scene

Collect the evidence

TWO (2) items which must be in the notes of a scene description:

Location address; the persons name; the date; compass directions.

Paper bags

are the preferred packaging material used in evidence preservation

The scene walk through allows an investigator to accomplish these tasks:

-properly identify evidence

-develop a plan

-use all one’s senses to gather information

(think Charlie Brown detective)

The information that should be recorded in a Crime Scene Log include:

-a person’s Arrival/Departure from scene

-a list of Suspect(s)

-the judge/ADA assigned (important)

Drone technology

is of use to the investigative process in many ways. Drones can be utilized in photography, sketching, crowd surveillance, searching large areas, tracking and site security. Also, drones can be utilized for intrusive searches of a scene.

When photographing crime scene evidence

it should not be rotated or moved for full photographic recording. Photographs must be a true and accurate representation of the scene. Also, not every photograph must include measurements and scale.

Sources of DNA evidence

include Body fluids and stains including blood and saliva. Hair, solid tissue, bone material including teeth and touch or contacted material which have cell materials.

Frances Glessner Lee

built the Nutshell Studies of Unexplained Death which were purpose-built to be used as police training tools to help Crime scene investigators to learn the art and science of detailed forensics-based detection.

Powder dust

is the most common physical method of processing fingerprints.

The primary duty of the first responder

is to preserve life and ensure safety

The fingerprints are unique and permanent are the

TWO (2) underlying premises of why FINGERPPRINT Identification can be used as a standard for personal identification. Identical Twins have the same DNA but DO NOT have identical fingerprints

Testimonial evidence

Witness statements, victim reports and spontaneous utterances

The interview of witnesses, suspects and others is an important part of the investigative process

The Reid technique uses questions such as “why would someone say you did this” or “who did you think would do this?” are meant to elicit responses beyond yes/no. If an answer seems unimportant interview theory suggests that such information is doubly important and forms the basis for further questioning

Physical evidence can -

important note-(might be multiple choice question)

-establish the identity of a person associated with the crime

-be used to corroborate the victim’s testimony

-be used to exonerate the innocent

-may be used by analysts or experts

The judge or magistrate

are considered the trier of fact

Transient evidence present at a Crime scene

is fragile or at great risk for loss, alteration or destruction

-important note (Don’t confuse with trace evidence)

The first technique for examining items for fingerprints

is visible examination followed by the use of alternate light sources.

Blood stain pattern analysis

is the use of the size, shape, and distribution patterns of the bloodstains found at a Crime scene to reconstruct the bloodshed event(s). REMEMBER Blood spatter, blood transfer and the directional flow of blood fluid are all parts of the blood shed event, all part of blood stain pattern analysis. Blood stain patterns are useful to reveal the identity of person(s) involved the circumstances of bloodshed and can guide conclusions about the nature of the causation of the blood event. Drying patterns and the condition of the blood are influenced by environmental factors such as temperature and humidity which makes determining timing difficult and/or inaccurate.

When determining the direction of travel of a blood event

the narrow end of a blood drop will point in the direction of travel

Trace evidence is collected by

photography followed by adhesive lifts, tweezers with a druggist fold or bindle paper fold

Trace evidence is known as

evidence that is small in size, such as hair, fibers, paint, glass, and soil which would require microscopic analysis

A Crime scene

is anywhere evidence may be located which helps to explain a specific event