Forensics Unit One: Eyewitnesses and Crime Scenes

Police and Eyewitnesses

After the Event

Factors that will affect witness memory and confidence

  • Time delay before questioning

  • Number of times questioned

  • method of questioning

Before the Interview

  • Get statement as close to time of the event as possible

  • If possible, place witness in the event environment

  • Before asking questions, ask the witness to recreate the scene in their mind

During the Interview

  • Start with unprompted recollection

  • Witness does the talking

  • Record both questions and answers

  • Witness tell the story from beginning to end

  • Follow up with specific questions

Avoid

  • Leading questions

  • Asking questions too quickly

  • Asking the same question more than once

  • Multiple choice questions

  • Interrupting the witness

  • Nonverbal cues indicating your opinion

Suspect Lineups: Foils/Fillers/Distractors

  • Should look like description not the suspect

  • Put the most similar foils next to the suspect

  • Pictures of foils and suspect should be similar quality, same clothing, same background, etc.

Securing a Crime Scene

Classifying Crime Scenes

Primary Crime Scene - Location where the crime occured

Secondary Crime Scene - Location where accessory event took place\

  • Planning

  • Transportation

  • Burial site for a body

Role of the police

Section off (isolate) the scene

This may grow or shrink under the direction of the CSI crew and/or detectives

Detain any witness or relevent bystanders

Securing the scene

Ensure no one enters or leaves

All first responders

Provide medical assistance

Case Study: JonBenet Ramsey

Case Details

Case took place December 26, 1996 in Boulder Colorado

Victim was 6-year-old JonBenet Ramsey

On the morning of December 26, JonBenet’s mother, Patsy, got up early to get ready for a trip the family was leaving for that day.

After waking up she discovered a ransom note

  • two page long ransom note - which is long for a ransom note

  • demanded $118,000  - strange amount

  • the note and draft of the note was written on a pad and using a pen that were inside the home

Securing the Scene

  • People were allowed to enter and leave the scene

  • People were allowed to roam around the house search the scene

  • They searched only the main living areas (kitchen and living roam)

  • They searched JonBenet’s room

Finding JonBenet Ramsey

  • Father and a friends decided to search the entire house

  • Found JonBenet dead in the basement

  • Picked her body up and took her upstairs to show the police

Photographing a Crime Scene

CSI Role: Document and Collect Evidence

Documenting Evidence

  • Sketch

  • Photo

  • Take photos on the way in and out of the scene

  • Don’t touch the scene

  • Set down evidence flags

  • List the numbers and label the evidence on the case file

Long Range Shots

Medium Range Shots

Shows evidence in proximity to each other

Close up Shots

Shows evidence up-close and size of the evidence (Measurement device is placed next to the evidence to give scale)

Sketching a Crime Scene

A crime scene sketch depicts the overall layout of the scene and the relationship to other relevant items and surroundings. Large things around the scene such as trees, streams, and big boulders.

Before the sketch

Obtain an overall view of the scene

Determine the sketch limits what is included

Sketches

Rough sketch is done at the scene and is basic shapes and measurements.

Elevation Sketch shows bullet trajectories

Perspective sketch is a 3d sketch of the space.

Crime Scene Reconstruction

Used to support a likely sequence of events based on the analysis of physical evidence and sometimes witness statements.

Scene reconstructions could be done to test the hypothesis for the events

Often done to walk juries through the most likely set of events at a scene

Objectivity - Personal detachment from the event to avoid bias in reconstruction

Falsifiability - Working with the notion that a hypothesis or theory can be disproven if given the proper evidence

Leaves the person open to new information

If you try to disprove the hypothesis or theory still stands, it becomes stronger

Limits in Reconstruction

Fallacy of Bifurcation - trying to give a simple ‘yes’ or ‘no’ to a complex question

Not all information will give a clear cut answer so don’t make it

Generalizations - helpful, but must be willing to give them up

False Linkage - Assuming a link between two items

Reconstructions for Juries/Investigation

Reconstruction needs to be clear and focused.

There may be more than one reconstruction - to show how events progressed.

Media used photos, drawings, computer reconstructions, models, diorama, etc.

Search Patterns

The first step after securing and defining the dimensions of a scene.

Evidence can be found on the ground, walls, and ceiling

As evidence is found: It is marked with a number and recorded on an evidence list

The five types of search patterns.

Collecting Evidence

  • Avoid contamination (wear gloves)

  • Collection techniques and storing of evidence depends on the type of evidence.

  • Biological evidence is dried and placed in a paper bag

  • Arson evidence is placed in a sealed can

  • May have to vacuum

Evidence Classification

Individual Characteristics

  • Evidence with unique properties

  • Can be linked to a source with a high degree of certainty

  • Examples: DNA and fingerprints

Class Characteristics

  • Lacks unique properties

  • Evidence associated with a group

  • Examples: Tire treads, ink, fabric

Legal Stuff

Legal search and seizure

Maintain a chain of custody

Presenting evidence in court

Presenting Evidence in Court

Two methods for the court to accept evidence for a trial/hearing

  1. Frye Standard - evidence whose collection, classification and examination technique is well known or whose methods are widely accepted by the scientific community

  2. Daubert Ruling - the judge acts as a gatekeeper for evidence