EXAM 1 PHYS FORENSIC SCI

Exam 1 for physical methods in forensic science

Physical Evidence

any materials or objects at the crime scene associated with the crime that was committed.

Crime scene management

requires securement, protection, and documentation of the scene.

Evidence management

Requires adoption of correct sampling and storing process

Who is the first person to arrive at the crime scene?

First responder

The First responder’s ________ ____ is to offer assistance to anyone who was injured at the scene.

overriding duty

Other than to assist people at the crime scene, what else is a first responder in charge of?

Preserving the crime scene

What should the first responder be documenting about the crime scene?

• State of the scene upon arrival

• existing condition upon arrival

• identity of all personnel at the scene (eyewitnesses, paramedics, etc.)

• Actions and statements of witnesses, victims, suspects and all other personnel who entered or exited the crime scene

• any items that may have been moved and who moved them

How big should the initial boundary be?

The initial boundary should be larger than the scene, expands outward from where the crime has occurred

Should you have a log of all individuals who entered and exited the scene?

Yes, you should have a log of all individuals and have a single path into and out of the crime scene

How many pairs of gloves should you have on?

Two nitrile gloves (change gloves OFTEN)

List PPE required for analyzing crime scenes that prevent contamination and protect the wearer.

• 2 nitrile gloves

• Eye and face protection: safety glasses and face shield

• Inhalation hazards: dust mask, air purifying respirator or self-contained breathing apparatus

• protective clothing: disposable synthetic coveralls and shoe covers

In what ways does documenting the scene and the evidence essential for crime scene analysis?

• Provides a permanent record of crime scene and location of physical evidence

• helps the analyst understand how evidence related to overall scene

What types of documentation are used in crime scene analysis?

• note taking

• photography

• sketching

• videography

Briefly describe this documentation:

Note taking

• Begins with the first responder

• Must be contemporaneous and recorded in chronological order

• errors should NOT be erased or pages torn out

• best way to refresh ones memory

What should notes taken at the scene include?

• Day, date, and time of arrival

• names of persons present at the scene on arrival

• detailed written description of scene with location of items of physical evidence recovered.

• time and location of recovery of an item and by who

• Record of who reported the incident, time and date at which it was reported and exact location of the scene

Briefly describe this documentation:

Photography

• crucial in court hearings and trials

• permanent visual record of the scene

• provides accurate measurements and distances among objects

• Condition of the scene MUST be unaltered in photos

• Objects MUST NOT be moved until photographed from all angles

What are the three shot rules?

• Overall shot

• Medium-range shot

• Close up shot

When photographing a dead body’s position and location in relation to the entire scene, what shot should you use?

Medium-range shot

When photographing any evident injuries on the body and/or weapons lying near the body, what shot should be used?

Close-up shots

What should a photo log include?

• Date and time

• Camera settings (F-stop, shutter speed, special lighting, etc)

• Camera make, model, and serial number

• file name and exposure number

• type of shot (Overall, mid-range, or close-up)

• distance to the subject

• Brief description of subject matter photographed

Briefly describe this documentation:

Sketching

• Made to document perspective and distance which would not be accurately reflected within photographs

• Purpose is to accurately record distances between objects at the scene

• Establishes the precise location and relationship of objects and evidence at the scene

Finalized sketches

Precise rendering of the crime scene and suitable for courtroom presentation

What are some measuring techniques and methods used?

• Triangulation method

• baseline method

• polar coordinate method

Briefly describe this documentation:

Videography

• Same principles used in crime scene photography apply

• the simultaneous audio track can provide added benefit, at times

• Video should COMPLEMENT, not replace, photographs

How should you search for evidence in a crime scene?

The search for physical evidence must be thorough and systematic

What evidence should you look for if the crime is a homicide?

Weapons, bullets, cartridges and cross-transfer evidence (hairs, fibers, blood, fingerprints, shoeprints, tire tracks, and soil)

What evidence should you look for if the crim is a pedestrian hit-and-run?

Cross-transfer on both the vehicle (blood and tissue, fabric, hair, and fibers) and the pedestrian (paint, plastic, glass, and tire impression)

What evidence should you look for if the crime is a burglary?

tool marks, broken glass, blood, fingerprints, and shoeprints

What evidence should you look for if the crime is arson?

Accelerants and ignition device

Questioned sample

(Unknown sample) collected at a crime scene

Trace evidence

Extremely small and often microscopic materials (glass shards, hairs, fibers, etc.)

Known sample

(reference or standard sample) collected from a known subject or object for comparison purposes

Substrate control

Uncontaminated surface material collected close to an area where physical evidence was recovered

What is the goal in packaging evidence?

To protect and preserve the evidence

How should you package each evidence item?

• Package each item separately

• Completely seal packages

Where do you package trace evidence in?

small paper envelopes

Where do you store small liquid samples?

Air-tight jars sealed with tape

Where can you store large liquid samples?

Paint cans with airtight seals. (Also can be used for charred debris in an arson scene)

How should a gun be stored?

In a cardboard box with zip ties

Why can’t blood samples go into airtight containers?

• Growth of mold and mildew can occur

How do you collect a blood sample from a crime scene?

• Allow wet blood found at the scene to air dry first

• once dried, it should be collected by scraping with a scalpel and placing it in paper envelope

• Wet sample can be collected on a swab, allowed to dry, and placed in a paper envelope

Chain of Custody

• Written chronological record of each person who handled or examined an item of evidence

How should burnt material be packaged as evidence?

Burnt material should be packaged in a paint can with an airtight seal

How should bloody clothing be packaged as evidence?

In a paper bag to prevent the blood from growing mold and mildew, and also to keep the DNA in tact.

What is a Search Warrant?

• Legal court orders which, upon establishment of probable cause, permit an exception to the fourth amendment (unlawful search and seisure)

What is an Arrest Warrent?

• legal court orders declaring there is probable cause to believe that the person to be arrested has committed a crime

Minimum requirements established by the certifying authority must be met to _________ __________.

warrant accreditation

What is classified as physical evidence?

• Tangible objects: items that are real, direct, and not circumstantial

• weapon used to commit a crime, trace evidence found at the crime scene (blood, fiber, hair), property recovered after crime was committed (fingerprints, shoeprint, handwriting)

What is classified as documentary evidence?

• any kind of writing, sound, or video recording, its validity authenticated by expert testimony

• transcript of a recorded telephone conversation

What is classified as demonstrative evidence?

• Real evidence used to illustrate, demonstrate, or recreate a prior event

• a cardboard model of the crime scene

What is classified as a testimony?

• Evidence in the form of witness speaking under oath in court

• eyewitnesses, hearsay witnesses, character witnesses

What three phases are involved in forensic science investigation?

• Recovery of evidence from crime scene

• Examination of evidence recovered at the crime scene

• Presentation of scientific test result in court

Individual Characteristics

• evidence can be associated with a common source with a high degree of probability

• E.g. comparison of handwriting characteristics

• typically involved application of stats

• “One to one” comparison (worn boots with same markings that can only be tied to one source)

Class characteristics

• evidence that can be associated only with a certain group and NEVER with a single source

• e.g. blood samples

• Example: the specific model of a shoe (many are possible)

Passive bloodstains

Formed from force of gravity rather than from pressure

Transfer bloodstains

Result of direct contact with an object that has blood on it

Active bloodstains

Caused by blood that travels because of force (impact)

Point of convergence

Identifies the place from where the blood originated using lines of a long axis using multiple spatters

Point of origin

Bloodstains that appear to have originated in the same place

Describe two ways of using blood stain patterns for reconstructing the crime scene

• patterns can be used to decipher circumstances of crime

• Can assist with determination of point of origin

Corpus delicti

A crime must be proven to have happened before a court can convict someone

To prove a case what needs to be established ?

MMO

• motive

• Means

• Opportunity

What makes evidence admissible in a court of law

Evidence should be Probative and material, or relevant to the case (consider Frye and/or Daubert standard)

Difference between layperson’s testimony and an expert witness testimony

Laypersons cannot state their personal opinions during testimony, only facts

Expert witnesses provide educated opinions based on their area of expertise. Cannot testify for either side