Forensic Science: Locard's Principle & CSI Basics

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What are the goals of CSI?

Recognize, document, and collect.

What does Locard's Exchange Principle state?

Whenever two objects come into contact, there is a cross-transfer of physical evidence.

What is an example of direct evidence?

Gun residue

Alibi

Motive

Video recording (correct)

What is circumstantial evidence?

Evidence that can imply or infer a fact but does not necessarily prove anything. Signup and view all the answers

Types of circumstantial evidence include , , and __.

physical, biological, trace Signup and view all the answers

What is physical evidence?

Items that can be collected from a crime scene. Signup and view all the answers

What is biological evidence?

Anything that was once on a living being or still is. Signup and view all the answers

What is trace evidence?

Small but measurable amounts of physical or biological material found at a crime scene. Signup and view all the answers

What is individual data?

Data that can be attributed to a single person with a high degree of certainty. Signup and view all the answers

What is class data/evidence?

Data that can be attributed to a group, such as blood type. Signup and view all the answers

Why is evidence important?

It can prove a crime, back up a witness or prove them false, link a suspect with a victim, determine identity of people, and allows investigators to reconstruct a crime. Signup and view all the answers

Can direct evidence be physical or biological?

False Signup and view all the answers

What type of evidence is a gun retrieved at a crime scene that matches the suspect's bullets?

Individual evidence. Signup and view all the answers

What type of evidence is a box of gloves that matches a pair of gloves found with the suspect?

Class evidence. Signup and view all the answers

Who are the members of a CSI team?

1st police on scene, backup police, medics, investigator, med examiner, photographer/field evidence tech, lab experts. Signup and view all the answers

What are the seven S's of CSI?

Secure the scene, separate the witnesses, scan the scene, see the scene, sketch the scene, search for evidence, secure and collect evidence. Signup and view all the answers

What does it mean to secure the scene?

Isolate the area after providing medical assistance and effecting an arrest if possible. Signup and view all the answers

Why is it important to separate the witnesses?

To avoid collusion and ensure accurate testimonies. Signup and view all the answers

What is meant by scan the scene?

Determine where photos should be taken and identify primary and secondary scenes. Signup and view all the answers

What is the purpose of seeing the scene?

Photograph up close with and without a measuring ruler. Signup and view all the answers

What is the significance of sketching the scene?

Accurately portray physical facts, relate sequences of events, and create a permanent record. Signup and view all the answers

Study Notes

Goals of CSI

Recognize, document, and collect evidence at crime scenes.

Locard's Exchange Principle

Proposed by Edmond Locard.
States that contact between two objects leads to a cross-transfer of physical evidence.
The extent of transfer depends on the intensity, nature, and duration of the materials involved.

Types of Evidence

Direct Evidence: Eyewitness accounts, videos, and confessions are considered direct proof of a crime.
Circumstantial Evidence: Implies or infers a fact but does not directly prove it, such as finding a gun at a scene suggesting a suspect's presence.

Categories of Circumstantial Evidence

Three main types: physical, biological, and trace evidence.
Can be classified as either individual (specific to one source) or class (common to a group).

Physical and Biological Evidence

Physical Evidence: Tangible items collected from a crime scene.
Biological Evidence: Material from living beings, such as hair, blood, or other bodily fluids.

Trace Evidence

Refers to small but measurable amounts of physical or biological material found at a crime scene, which can be either physical or biological in nature.

Individual and Class Evidence

Individual Evidence: Can be linked to a single individual with high certainty, such as a matching bullet to a suspect's gun.
Class Evidence: Associated with a group, such as a blood type or a type of fabric.

Importance of Evidence

Can prove a crime, back up or disprove a witness, link a suspect to a victim, determine identities, and help reconstruct the crime.

Evidence Types Specifications

Direct evidence can only be testimonial; it cannot be categorized as physical, biological, individual, or class evidence.

Role of CSI Team Members

Initial responding officers, backup police, medics, investigators, medical examiners, photographers, field evidence technicians, and lab experts make up a CSI team.

Seven S's of CSI Process

Secure the scene, separate witnesses, scan the scene, see the scene, sketch the scene, search for evidence, and secure and collect evidence.

Securing the Scene

The first officer must ensure the area is isolated and call for specialists after addressing any immediate medical needs or apprehending suspects.

Separating Witnesses

Important to prevent collusion by asking each witness six key questions.

Scanning the Scene

Assess where photos should be taken and identify primary and secondary scenes.

Seeing and Documenting the Scene

Photography should be done both close-up and with measuring rulers for context.

Sketching the Scene

Create accurate representations of physical facts, understand event sequences, and mark locations of objects.
Include rough and finished sketches, label north (N), and use a scale. Measurements should be referenced from immovable objects, such as walls.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the fundamentals of forensic science with a focus on Locard's Exchange Principle and the foundational Seven S's of Crime Scene Investigation. This quiz covers essential terminology and concepts crucial for understanding crime scene protocols and evidence handling.