Chapter 2 Vocabulary Physical Evidence

Any object that can establish that a crime has been committed or can link a crime and its victim or its perpetrator.

Chain of Custody A list of all people who came into possession of an item of

evidence. Standard/Reference Sample

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

Buccal Swab A swab of the inner portion of the cheek; cheek cells are usually

collected to determine the DNA profile of an individual. Substrate Control

Uncontaminated surface material close to an area where physical evidence has been deposited. This sample is to be used to ensure the surface on which a sample has been deposited does not interfere with laboratory tests.

SEARCH METHODS

Line or strip method—best in large, outdoor scenes

Grid method—basically a double-line search; effective, but time-consuming

Zone method—most effective in houses or buildings; teams are assigned small zones for searching

Spiral method—may move inward or outward; best used where there are no physical barriers

Types of EvidenceTwo general types:

Testimonial—a statement made under oath Direct evidence or Prima Facie evidence

Physical—any object or material that is relevant in a crime Indirect evidence Examples: hair, fiber, fingerprints, documents, blood, soil,

drugs, tool marks, impressions, glass.

Value of Physical Evidence

Generally more reliable than testimonial Can prove that a crime has been committed Can corroborate or refute testimony Can link a suspect with a victim or with a

crime scene Can establish the identity of persons

associated with a crime Can allow reconstruction of events of a crime

Reconstruction

Physical Evidence is used to answer questions about:

what took place how the victim was killed number of people involved sequence of events

A forensic scientist will compare the questioned or unknown sample with a sample of known origin.

Types of Physical Evidence Transient Evidence—temporary; easily changed or lost; usually

observed by the first officer at the scene Pattern Evidence—produced by direct contact between a person

and an object or between two objects Conditional Evidence—produced by a specific event or action;

important in crime scene reconstruction and in determining the set of circumstances or sequence within a particular event

Transfer Evidence—produced by contact between person(s) or object(s), or between person(s) and person(s)

Associative Evidence—items that may associate a victim or suspect with a scene or each other; ie, personal belongings

DISCUSS WITH A NEIGHBOR AND COME UP WITH 2 EXAMPLES OF TRANSIENT, PATTERN, OR CONDITIONAL EVIDENCE.

—Lee and Labriola in Famous Cases, 2001

Chapter 3

Examples of Transient Evidence

Odor—putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smoke

Temperature—surroundings, car hood, coffee, water in a bathtub, cadaver

Imprints and indentations—footprints, teeth marks in perishable foods, tire marks on certain surfaces

Markings

Examples of Pattern Evidence

Pattern Evidence—most are in the form of imprints, indentations, striations, markings, fractures or deposits.

Clothing or article distribution

Gun powder residue Material damage Body position Tool marks Modus operandi

Blood spatter Glass fracture Fire burn pattern Furniture position Projectile trajectory Tire marks or skid marks

Examples of Conditional Evidence

Light—headlight, lighting conditions

Smoke—color, direction of travel, density, odor

Fire—color and direction of the flames, speed of spread, temperature and condition of fire

Location—of injuries or wounds, of bloodstains, of the victim’s vehicle, of weapons or cartridge cases, of broken glass

Vehicles—doors locked or unlocked, windows opened or closed, radio off or on (station), odometer mileage

Body—position, types of wounds; rigor, livor and algor mortis

Scene—condition of furniture, doors and windows, any disturbance or signs of a struggle

Classification ofEvidence by Nature

Biological—blood, semen, saliva, sweat, tears, hair, bone, tissues, urine, feces, animal material, insects, bacterial, fungal, botanical

Chemical—fibers, glass, soil, gunpowder, metal, mineral, narcotics, drugs, paper, ink, cosmetics, paint, plastic, lubricants, fertilizer

Physical—fingerprints, footprints, shoe prints, handwriting, firearms, tire marks, tool marks, typewriting

Miscellaneous—laundry marks, voice analysis, polygraph, photography, stress evaluation, psycholinguistic analysis, vehicle identification

Evidence Characteristics

Class—common to a group of objects or persons

Individual—can be identified with a particular person or a single source

Blood DNA TypingFingerprints

Chapter 3

Class vs Individual Evidence

Which examples do you think could be individual evidence?

COLLECTING AND PACKAGING EVIDENCE

One individual should be designated as the evidence collector to ensure that the evidence is collected, packaged, marked, sealed, and preserved in a consistent manner

Each item must be placed in a separate container, sealed, and labeled

Most fragile is collected and packaged first Different types of evidence require specific or special

collection and packaging techniques The body is the property of the coroner or medical

examiner. The collection of evidence on the body is done by that department

PACKAGING

Most items should be packaged in a primary container and then placed inside a secondary one. These are then placed inside other containers such as paper bags, plastic bags, canisters, packets and envelopes depending on the type and size of the evidence.

CHAIN OF CUSTODY

There must be a written record of all people who have had possession of an item of evidence. The evidence container must be marked for

identification The collector’s initials should be placed on the

seal If evidence is turned over to another person, the

transfer must be recorded.

Chapter 2 Vocabulary

Rough Sketch A draft representation of all essential

information and measurements at a crime scene. This sketch is drawn at the crime scene.

Finished Sketch A precise rendering of the crime scene, usually

drawn to scale.

CORPUS DELICTI“Body of the Crime”

You must prove that a crime occurred that the person charged with the crime was responsible for the

crime

Source of Evidence Body Primary and/or Secondary Crime Scene Suspect(s)

CRIME SCENE TEAM

A group of professional investigators, each trained in a variety of special disciplines.

Team Members First Police Officer on the scene Medics (if necessary) Investigator(s) Medical Examiner (if necessary) Photographer and/or Field Evidence Technician Lab Experts

CRIME SCENE INVESTIGATION

Based on the scientific method and the Locard Exchange Principle, logic and forensic techniques

Involves: Recognition—scene survey, documentation,

collection Identification—comparison testing Individualization—evaluation and interpretation Reconstruction—reporting and presenting

PROCESSING ACRIME SCENE

Isolate and secure the scene

Document the scene Search for evidence Collect and package

evidence, maintaining the chain of custody

Submit evidence to the crime lab

FIRST OFFICERON THE SCENE

A Assess the crime scene and assist those hurt

D Detain the witness

A Arrest the perpetrator

P Protect the crime

scene

T Take notes

CRIME SCENE SURVEY

Walk-through—performed by the crime scene investigator, the first officer and sometimes the lead detective

Purpose: Mentally prepare a reconstruction theory Note any transient or conditional evidence that could change over time. Note weather conditions Note points of entry or exit, as well as paths of travel within the crime

scene Record initial observations of who, what, where, when, and how Identify special needs within the crime scene for personnel, precautions

or equipment and notify superior officers or other agencies

DOCUMENTATION

Notes—date and time, description of the location, weather and environmental conditions, description of the crime, location of the evidence relative to other key points, the names of all people involved, modifications that have occurred and other relevant information

Photography—photos of scene and surroundings, mid-range to close-up photos with various angles of each piece of evidence, photos as viewed by any witnesses.

Sketches—inclusion of date, time, scale, reference points, distance measurements, names of investigators, victims, suspects, and a legend (key)

Videography—allows narration (non-subjective) to be included

CRIME SCENE SKETCH

Date: August 14, 2005 Criminalist: Ann WilsonTime: 11:35 am Location: 4358 Rockledge Dr, St. Louis, Mo.

N

Guest Speaker Questions

Sgt. Katherine Scheimreif from the CMPD will be our guest speaker on September 16

Sgt. Scheimreif is the Unit Leader of the Crime Scene Search team

Come up with 2 questions that you could ask her based on what we have learned so far or that directly relate to a crime scene

Chapter 1 Review

If your group is waiting to complete the lab then you can work on the Chapter 1 Review questions, #1-29 on pages 33-34

Recording a Crime Scene Lab

Read over the background information and instructions of the lab so that your group will be prepared when you enter the crime scene.

Determine who will be completing the following tasks in your group: Sketcher – complete the sketch Photographer- take all photographs that are needed Recorder – take measurements of crime scene and record

data in the data table Manager (if extra person) – make sure group completes

all required parts; place numbered markers and help others as needed

Recording a Crime Scene Lab

When you have left the crime scene, complete the procedures for after the crime scene.

Be sure to work together as a team to complete the sketch and to go through the photographs.