Forensic Science Lesson 04: Investigation&Evidence Collection 1

Crime Scene Investigation and Evidence Collection Part 1

Multiple Choice

True or False: The word Forensic refers to the application of scientific knowledge to legal questions.

• True

• False

Multiple Choice

Which type of forensic science deals with insects found at a crime scene?

• Forensic Botany

• Forensic Geology

• Forensic Psychology

• Forensic Entomology

Multiple Choice

True or False: If we remember seeing something happen, we can trust that it hap- pened just as we think it did.

• True

• False

Multiple Choice

The Innocence Project found that most faulty convictions were based on

• Out-of-date investigating equipment

• Poor DNA Sampling

• Inaccurate eyewitness accounts

• Officers not thoroughly investigating a crime scene

Lesson Objectives:

• Summarize Locard's Exchange

• Identify Examples of Trace Evidence

• Distinguish between Direct and circumstantial Evidence

• Summarize the seven steps of a crime-scene investigation

• Explain the importance of securing a crime scene

• Identify how a crime scene is documented

• Demonstrate proper technique in Collecting and Packaging Trace Evidence

• Describe how evidence from a crime scene is analyzed

• 1996 Boulder CO- 6 year oldJonBenet's Family find her missing with a ransom note

• Police come to the home, and close off her room, but not the rest of the house

  • Think it is a kidnapping and don't search the house

• Later in the Day, her father finds her body in the basement, attempts to revive and Brings upstairs

  • Visitors to comfort the family arrive before the police, contaminating the scene by moving furniture, eating, and cleaning

• The crime is still unsolved, but investigators have reopened the case due to advances in DNA Testing

Case File: JonBenet Ramsey

Introduction

• Crime-Scene Investigation: A multidisciplinary approach in which scientific and legal professionals work together to solve a crime

  • Ultimate goals

    • Recognize, document, and collect Evidence at the scene

    • Piece together evidence to figure out what happened

Principle of Exchange

• When two things come in contact, some material is transferred from one to another

  • Hair/Skin cells

  • Fibers

  • Pollen

  • Debris

• Trace Evidence: Small but measurable amounts of physical or biological material found at a crime scene

Forensic Science | Chapter 2: Crime Scene Investigation and Evidence Collection

Locard's Exchange Principle

• The First Person to write about the exchange of trace evidence was Dr. Edmond Locard

  • Lead the first forensic Laboratory in France

• Locard's Exchange Principle: When a person comes into contact with an object or person, a cross-transfer of physical evidence can occur, indicating the two objects were in contact

  • "The Silent Witness"

  • The amount that is transferred varies based on the type and length of contract

Direct Evidence

• Direct Evidence: Evidence that Proves an alleged fact

  • Witness testimony

    • Must indicate what they saw happen

  • Video Evidence

  • Confession

Circumstantial Evidence

• Circumstantial Evidence: evidence that can imply a fact, but not prove it directly

  • indirect evidence

  • Is either physical or biological

    • Physical Evidence: Helps limit the pool of potential suspects

    • Biological Evidence: Pinpoints a couple of suspects or one individual

  • Only the people involved know the truth, but circumstantial evidence can provide investigators with a link

  • All Trace Evidence is Circumstantial Evidence

Forensic Science | Chapter 2: Crime Scene Investigation and Evidence Collection

Multiple Choice

Which of the following is an example of direct evidence?

• A security camera showing a suspect shoplifting

• A suspect's fingerprints on a weapon

• A drop of the suspect's blood found at the crime scene

• The suspects car is parked in a suspicious place

Drag and Drop

​

Placeholder

evidence is any small but measurable amounts of physical or biological material found at a crime scene.

Drag these tiles and drop them in the correct blank above

Trace

Direct

Indirect

Locard's

Multiple Choice

True or False: Circumstantial Evidence proves a fact of the case.

• True

• False

Class Evidence

• Class Evidence: Narrows an identity down to a group of persons or things

  • Examples: Blood type, hair color, hair type

Individual Evidence

• Individual evidence: Narrows an identity down to a single person who has that characteristic

  • Example: Fingerprints, DNA Samples

• Class Evidence can sometimes lead into Individual evidence, but not always

Who Investigates a Crime Scene?

• Police Officers

  • Usually first to arrive

    • Maybe accompanied by a District attorney if a warrant may be needed

  • Are in charge of securing the scene

    • Generally do not touch the actual scene unless they absolutely must

      • Example: Thinking a victim may still be alive and trying to revive them

Who Investigates a Crime Scene?

• Crime Scene Investigators: Specialized detectives with forensic knowledge

  • Document the scene using photographs, sketches, and evidence collection

    • No one person does all these jobs, each person specializes in a certain aspect

  • May be called to testify in court about how evidence was found/handled

Who Investigates a Crime Scene?

• Medical Examiners/Coroners: Maybe present if the crime involves a body

  • Determine a preliminary cause of death

• Detectives: Interview Witness and investigators to put findings together into a preliminary report

• Specialists: Scientific investigators highly qualified in a unique field called in as situations need them

  • entomologists, botanists, psychologists

Forensic Science | Chapter 2: Crime Scene Investigation and Evidence Collection

Categorize

Options (11)

Eye witness account

Video Recording of the crime

Confession

DNA Sample

Fingerprint

A suspects driver's license found at the scene

hair color

height

shoe size

blood type

Car type

Organize these options into the right categories

Class Evidence

Individual Evidence

Direct Evidence

Multiple Choice

True or False: A police officer is generally in charge of collecting forensic evidence at a crime scene.

• True

• False

Multiple Choice

All of the following are ways to improve our observational skills except

• write down and photograph everything you find

• when collecting evidence, record only those things that you are sure are important

• observe everything no matter how big or small

• be sure to look at the entire area, not just the body, weapons, or signs of a break-in

Multiple Choice

Locard’s exchange principle implies all of the following except

• Fibers can be transferred from one person to another.

• Blood spatter can be used to identify blood type.

• Cat hair can be transferred to your pants.

• Soil samples can be carried from the yard into your home.

The Seven S's of Crime Scene Investigation

• There are seven key steps to investigating a crime scene, that must occur in the proper order for an investigation to run smoothly

  • Securing the Scene

  • Separating the Witnesses

  • Scanning the Scene

  • Seeing the Scene

  • Sketching the Scene

  • Searching for Evidence

  • Securing and Collecting Evidence

Forensic Science | Chapter 2

Securing the Scene

• The responsibility of the first responder (Police Officer)

• Number one Priority: Guaranteeing the safety of all individuals in the area

  • Preserving evidence is a secondary goal

• Prevents people from leaving or entering an area

• Collect important information from witnesses and make sure the threat is no longer present

• Calls for specific specialists who may be needed

Forensic Science | Chapter 2

Separating Witnesses

• Making sure witnesses are not talking to each other and comparing what they saw

  • Collusion: cooperation to create a story

    • May or may not be intentional

• As witnesses are separated, the following questions are asked

  • When did the crime occur?

  • Who called in the crime?

  • Who is the Victim?

  • Can you identify the perpetrator?

  • Where were you when the crime happened?

  • What did you see?

Forensic Science | Chapter 2

Scanning the Scene

• Preformed by Forensic examiners

• Quickly look over the scene to determine where photos should be taken

  • Determining the type of Crime scene

    • Primary Crime Scene: The Location a crime took place

    • Secondary Crime Scene: A location related to the crime with evidence, but not the place where the crime took place

      • Example: The home of a suspect

• Assigns priority to investigations

  • Determines what looks to be the most critical to investigate first

Forensic Science | Chapter 2

Multiple Select

Which of the following steps of the investigation can be handled by a first responder? Select all that apply

• Securing the scene

• Separating Witnesses

• Scanning the scene

Multiple Choice

A store is robbed. One of the witnesses texted her mother, who was shopping on the other side of the store asking if she saw anything. This causes a problem with which step of the investigation?

• Securing the scene

• Separating Witnesses

• Scanning the scene

• There is no problem

Multiple Choice

A store is robbed. The officer who arrives locked down every exit except one that the clerk forgot to tell him about. This causes a problem with which step of the investigation?

• Securing the scene

• Separating Witnesses

• Scanning the scene

• There is no problem

Multiple Choice

A store is robbed. The crime scene investigation crew arrived before the forensic investigator and began searching for evidence. This causes a problem with which step of the investigation?

• Securing the scene

• Separating Witnesses

• Scanning the scene

• There is no problem

Multiple Choice

A store is robbed. The forensic Investigator sees that the perpetrator walked into the main body of the store and committed the robbery there, so they declare that the primary crime scene. This causes a problem with which step of the investigation?

• Securing the scene

• Separating Witnesses

• Scanning the scene

• There is no problem

Seeing the Scene

• Preformed by Crime Scene Investigators

• Involves taking photos of the scene

  • Photos are taken both with and without measurement tools like rulers to help set a scale

  • Certain objects are chosen to help set a baseline for comparison

  • Photos are taken at as many angles and distances as possible

Forensic Science | Chapter 2

Sketching the Scene

• Preformed by Crime Scene Investigators

• A "map" of the scene is drawn on paper to help place all evidence in the location it was found

• Includes all aspects of the scene

  • Furniture, trees, buildings, vehicles

• Shows North and distance scale

• Records date, location, and type of crime

• Is drawn by hand and then generally tidied up on a computer for neatness

Forensic Science | Chapter 2

Searching for Evidence

Forensic Science | Chapter 2

• Preformed by Crime Scene Investigators

• The investigating team chooses a pattern to follow to go over the scene looking for evidence

  • The method used is based on the number of investigators present

    • Single Investigator may use a grid, linear or spiral pattern, while multiple investigators split the scene into quadrants/zones

Searching for Evidence

Forensic Science | Chapter 2

• Use of additional materials may be needed

  • Flashlights: illuminates evidence

  • Forceps: Helps pick up materials without gathering extra material

  • Vacuum with a clean bag: Collects Fiber Evidence

    • Should be used as a last resort, because it picks up extra material

Multiple Choice

A crime scene investigator takes pictures of a piece of evidence but has the ruler upside down so you can't see the scale. This causes a problem with which step of the investigation?

• Seeing the Scene

• Sketching the Scene

• Searching for Evidence

• Scanning the Scene

Multiple Choice

A crime scene investigator needs to scan the area of a crime, but the other people on their team are busy doing other tasks. Since they are working alone, which method of searching would they not use?

• Grid

• Linear

• Quadrant/Zone

• Spiral