FSC100~ Exam

Define First Responder Responsibilities at a crime scene

First responders must:

- Preserve life unless signs of obvious death are present (e.g., decapitation, decomposition).

- Provide emergency medical aid if applicable.

- Secure the scene and prevent contamination of evidence.

Define the Term “chain of custody”

Chain of custody refers to the documented and unbroken transfer of evidence from the crime scene to the courtroom, ensuring its integrity

How should biological evidence be persevered

- Air-dry samples to prevent degradation.

- Store in paper containers or envelopes.

- Avoid airtight plastic containers to prevent mold and decay.

- Keep refrigerated or frozen if required.

How is trace evidence collected and preserved?

Use disposable tweezers or adhesive tape to collect small items like fibers or hair.

- Store in druggist folds or sealed evidence bags.

- Label and document the source location.

What is the process for preserving firearm evidence

Avoid handling the barrel or grip to preserve fingerprints.

- Secure in a rigid container.

- Remove and separately package ammunition.

- Label all items and document handling.

How is blood evidence preserved?

- Collect liquid blood with sterile swabs and air-dry.

- Use moistened swabs for dried stains.

- Package in paper bags or envelopes with biohazard labeling.

- Refrigerate or freeze samples to maintain stability.

How should footwear and tire impressions be preserved

- Photograph impressions with scales for context.

- Use casting material like dental stone for 3D impressions.

- Protect casts in rigid containers during transport.

What is the method for preserving digital evidence

- Use write-blockers to prevent data alteration.

- Create forensic copies for analysis.

- Secure devices in anti-static bags and document chain of custody.

How should drug evidence be preserved?

- Place powders, tablets, or plant material in sealed plastic bags or vials.

- Label with case information and document weight.

- Store in a controlled environment to avoid contamination.

What precautions are necessary for preserving volatile evidence?

- Collect in airtight containers, such as glass jars or metal cans, to prevent evaporation.

- Store in a cool location to stabilize volatile compounds.

- Minimize exposure to air and light.

What are the three fingerprint patterns

1. Loops: Found in 60-65% of the population. Includes radial and ulnar loops.

2. Whorls: Found in 30-35%. Includes plain and double-loop whorls.

3. Arches: Least common at about 5%. Includes plain and tented arches.

What are latent fingerprints?

invisible prints left by the transfer of natural oils or sweat from a finger, requiring development techniques for visualization.

What are patent fingerprints?

Visible prints left when fingers come into contact with a substance like ink, blood, or dirt and transfer it to a surface.

WHat are plastic fingerprints?

Plastic fingerprints are three-dimensional impressions left on soft surfaces such as wax, clay, or wet paint.

Define ridge minutiae

Ridge minutiae are unique features of fingerprint ridges, such as bifurcations, ridge endings, islands, and dots, used for individual identification.

What is the ACE-V method

ACE-V is a systematic process for fingerprint analysis:

1. Analyze: Assess quality and clarity of the print.

2. Compare: Match points of similarity between prints.

3. Evaluate: Determine if the prints match.

4. Verify: Peer review to confirm conclusions.

Define passive bloodstains

Passive bloodstains are created solely by the force of gravity, such as drips, pools, or flows.

What are impact spatter patterns

Created when blood is subjected to a force, such as a gunshot, blunt object impact, or stabbing.

How is the angle of impact calculated for bloodstains?

The angle of impact is calculated using the formula:

- Sin⁻¹ (Width / Length) of the bloodstain.

Define the term “void pattern” in blood spatter analysis

A void pattern occurs when an object blocks the path of blood, leaving a blank space within the bloodstain pattern.

What are transfer bloodstains?

Transfer bloodstains are created when a bloody object comes into contact with a surface, resulting in patterns like smears, swipes, or wipes.

What is the role of an expert witness in court?

An expert witness provides specialized knowledge to explain forensic evidence, interpret findings, and deliver unbiased testimony in court.

Define direct examination

Direct examination is the initial questioning of a witness by the side that called them, aiming to establish facts that support their case.

Define cross-examination

Cross-examination involves the opposing side questioning a witness to challenge their credibility or uncover inconsistencies in their testimony.

What is voir dire?

a preliminary examination of a witness or juror to determine their qualifications, biases, or suitability for testimony or jury service.

What are class characteristics of Firearms?

measurable features of a firearm, such as caliber, number of lands and grooves, and direction of rifling.

What are individual characteristics of firearms?

Unique, microscopic markings left on bullets or cartridge cases by the firearm due to wear and manufacturing defects.

Define the term “toolmark”

Any impression, cut, gouge, or abrasion caused by a tool coming into contact with another object, often used to link a tool to a crime.

What are striations used in tool mark analysis?

Striations are microscopic scratches on a surface caused by a tool, which can be matched to the specific tool that created them.

What is the purpose of a comparison microscope in firearms analysis?

A comparison microscope allows side-by-side examination of bullets or toolmarks to determine if they share the same origin.

What does the term “Evidencia” mean?

 To be visible

What does videre mean"?

to see

What are the types of evidence?

Testimonial Evidence

Documentary Evidence

Real Evidence

What is testimonial evidence?

• Oral evidence or viva voce evidence 

• Evidence given verbally by a witness during a testimony

What is documentary evidence?

• Consist of documents of any kind

• Handwritten or mechanically produced (messages, laptops)

What is real evidence?

• Physical evidence

• Biological evidence

  • CSI most often come across in the crime scene

what are the types of physical real evidence?

• Fingerprints

• Footprints

• fibers

• paint

• tire impressions

• firearms

• toolmarks

• glass

What are the types of biological real evidence?

• DNA and body fluids 

• hair, skin, bone

• flora

• fauna

Define direct evidence

• Proves or disproves an important fact beyond speculation

• Based on personal knowledge or observation

• Refers primarily to testimonial evidence

Define indirect evidence

aka. circumstantial evidence

• Relies at least partially on speculation but logically supports a fact

• Refers to testimonial evidence and/or physical evidence

• Most CSI work with circumstantial evidence 

• Forensic scientist have to provide explanation 

• Based on reasoning and not direct observation

What is associative evidence?

• Any real evidence that places an individual directly at the crime scene or as having had direct contact with the victim

• Provides linkages between:

  • Suspect and victim

  • Suspect and crime scene

  • Victim and crime scene

Provide examples of associative evidence

•  fingerprints at a crime scene 

• strand of suspects hair on body of deceased (associative real evidence, biological evidence) 

What is Indicative evidence?

Any real evidence which substantiates or proves that a certain amount of time has elapsed

not generally collected

What is class evidence?

real evidence that requires precise classification for use in Court

• Requires classification into a more narrow range

• Collective in nature

  • E.g., blood, semen, or hair

What is latent evidence?

 real evidence that is often not visible without chemical, photographic, or electronic

What is trace evidence?

Real evidence that must be extracted from another substance or item

• often microscopic

What is Seriology?

• The analysis of properties and effects of body fluids

  • Liquid state or dry state

    • Stain form

What is DNA?

 deoxyribonucleic acid

• Human body composed of cells

• Inside almost every cell is a nucleus

• Nucleated cells have 46 chromosomes

  • 23 matching pairs

    • 1 from mother, 1 from father

What are the types of DNA?

• Nuclear DNA

• Mitochondrial DNA (mtDNA)

What is nuclear DNA?

• Found in nucleus of cells

• One copy per cell

• Equal contribution from each parent

• Unique to the individual

  • Most valuable in criminal individual

What is mitochondrial DNA (mtDNA)

• Found in the mitochondria of each cell 

• Many copies within each cell

• Transmission through the maternal line

  • Not unique to the individual

    • Use more limited

What are the presumptive tests for blood?

• Color spot tests

  • Rely on properties of hemoglobin

    • Hemoglobin: Oxygen-carrying molecule that is found in blood

  • Sensitive

  • Easy to perform

What is the documentation procedure for collection of blood evidence?

• Location

• Date and time

• Name of the CSI

• Which test(s) performed

• Lot number and expiration of chemicals

What is luminol and what is it used for?

• Sprayed and viewed using special light sources

• Reacts to iron (heme) in blood

  • Will fluoresce

  • Chemiluminescence

What are the advantages and disadvantages of luminol?

• Advantages:

  • Highly sensitive

  • Does not interfere either DNA testing

• Disadvantages:

  • Requires complete darkness

  • Faint luminescence

  • False positives to substances containing iron

What is Bluestar?

• Developed to overcome problems with luminol

  • Most crime scene investigators now prefer Bluestar

what are the advantages of Bluestar over luminol?

• Non-toxic

• Total darkness not required

• Stronger luminescence

• Longer lasting reacion

• Higher sensitivity

• Also does not interfere with DNA analysis

What is Hemastix and what is it used for?

• Originally to test the presence of blood in urine

• Colour change from 0-6

  • 6 = indicates the presence of blood

What are the disadvantages of Hemastix?

• Interferes with DNA analysis 

  • Do not test the stain itself

    • Swab stain, test swab

• False positives with rust, bleach, and vegetable

What is Phenolphthalein (Kastle-Meyer)?

• Conducted on filter paper or swabs

• Reagent utilized with hydrogen peroxide

• Colour change

  • Pink in presence of blood

What are the disadvantages of Phenolphthalein (Kastle-Meyer)?

• Interferes with DNA analysis

  • Do not test stain itself, swab stain, test swab

• False positives:

  • Horse radish and potatoes

What is the Acid Phosphate (AP) colour test utilized for?

• Presumptive test for seminal fluid

• Utilized with alternate light sources

  • Seminal fluid will fluoresce under certain wavelengths of light

• Once located, perform presumptive tests

What does the Acid Phosphate (AP) do?

• Acid phosphate: enzyme secreted by the prostate gland into seminal fluid

How do you read the AP colour test results?

• Swab stain with clean, sterile swab or filter paper, apply reagent

  • Purple indicates probable presence of semen

    • True positive in 30 seconds

    • Recorded as negative if no colour change within 2 minutes

• False positives with other body fluids, fungi and contraceptive creams

How is bite mark evidence collected?

• Moisten swab with distilled or sterile deionized water and run over suspected bite wound

• Follow with dry, sterile swab for collection

How is collection of bodily fluids performed (liquid state)?

• Wet body fluid stains

• Place sterile swab or filter paper into still-liquid sample and allow it to be fully saturated

• Air-dry and preserve in paper envelope or paper evidence bag

  • If not permissible may use platic bag for transportation purposes

How is collection of bodily fluids performed (dry state)?

• More common in crime scene investigation contexts

• Cut out stain or scrape stain into sterile filter paper

• To swab a dry stain:

  • Moistenswab with distilled or sterilized, deionized water

  • Follow with dry swab for collection

What is the procedure for preservation of bodily fluids?

• Air dried at room temperature

• Packaged loosely in paper evidence bag

• Thoroughly documented

How is the documentation of bodily fluids done?

• Name or initial of individual collecting that evidence

• Date of item collection and teransfer

• Agency,Case number, Crime type

• Storage location

• Brief description

• Packaged with biohazard label

What are the confirmatory tests for blood?

• Hemochromagen chemical test

  • No false positives

• Teichmann test

• Takayama test

  (used to differentiate between human and animal, further tests for individualization)

What are the confirmatory tests for seminal fluid?

• Microscopic examination for spermatozoa

  • Staining techniques to assist in visualization

    • Differentiate sperm cells from extraneous material

What are the confirmatory tests for saliva?

• No specific tests

• Previously tested for presence of amylase

  • Enzyme present in saliva and other body fluids

What is CODIS?

• DNA profiles entered into CODIS

  • Compared with victim

    • Elimination purposes

  • Compared with possible suspects

• 4 local investigative indices (2013):

  • Ottawa, Regina, Edmonton, Vancouver

  • Also:

    • Center of Forensic Sciences and Laboratoire de sciences judiciaires et de medicine légale

What is the National DNA Data Bank (NDDB)?

• After entered in CODIS, profile entered in National DNA Data Bank (NDDB)

  • Maintained in Canada

• NDDB includes:

  • Convicted Offender Index (COI)

    • DNA profiles collected from convicted offenders

  • Crime Scene Index (CSI)

    • ONA profiles obtained from crime scene investigations

• If no matches, profile maintained in NDDB

Define a Delta?

Ridges converge from three directions

What is the Core?

Inner most area of fingerprint pattern

What is a recurving ridge?

Any fingerprint ridge that retraces its course

What are the types of loops?

Radial and Ulnar

What is a radial loop?

• Loop flows towards rthumb

  • Ridge from side

  • Ridge recurvesto exit in thumb side

• One delta

What is an ulnar loop?

• Loop flows towards little finger

  • Ridge enters from little finger side

  • Ridge recurves to exit on little finger side

• One delta

What are the types of whorls?

plain, central pocket, double, accidental

What is a plain whorl?

• 1+ recurving ridges, 2 deltas

• Straight line between deltas bisects ridge(s) at core

What is a central pocket loop whorl?

• 1+ recurving ridges, 2 deltas

• Straight line between deltas does not bisect

WHat is a double loop whorl?

2 loop formations(separate and aparts (2 deltas)

What is an accidental whorl?

• Non-specific; 2 deltas

• Upthrust: Ridge flow unusial, in upward direction

What are the types of arches?

plain and tented

What is a plain arch?

• Ridges run in one side, out the other

• Smooth arching formation

• No delta

What is a tented arch?

• Ridges run in one sode, out the other

• Upthrust in middles

  • Appearance of a tent

• No delta

What are the types of minutiae?

Short ridges, Splitting ridges, Dot, Ending ridge, Crossover, Island

How are fingerprints photographed?

• High-intensity light that emits visible and invisible light beams to locate fingerprints

• Used with various filters

  • Always wear safety goggles

• Increase likelihood of identification by continually altering angle of light source

• Once latent print identified, photography using white light

  • At oblique angle

what is fingerprint powder used for?

Developing latent prints that have been identified with an alternate light source, and searching for latent prints

What are the advantages of fingerprint powder?

• Allows for lifting of the fingerprint

• Preservation of the fingerprint as physical evidence

• Fast

• Inexpensive

• Convenient

What are the types of fingerprint powders?

Granular

Flake

Magnetic

What is the granular powder?

• Large, spherical grains which adhere to secretions

• No designed for lifting

• Application:

  • Animal hair brusg

  • Gentle brushing motion

• Works best on:

  • Lighlty grained surfaces

  • Surfaces that may be damged by lifting

What is the flake powder?

• Aluminum, gold,bronze

• Designed for lifting

• Application:

  • Zephyr brush

  • Twirling motion

• Works best on:

  • Smooth surfaces

  • Non-porous surface

What is the magnetic powder?

• Contain iron

• Designed for lifting

• Application:

  • Magnetic wand 

  • Granular or flake

• Works best on:

  • More porous

    • Articles such asmagazines or paper

What is the process of documentation for fingerprints?

• All fingerprints must be photographed before collection because:

  • Shows location and direction of fingerprint in situ

  • Records most complete detail

• Fingerprint evidence should be photographed:

  • 1:1 in real size

  • With a scale ruler included

  • With a label that includes:

    • Crime scene investigators name or initials

    • Fingerprint number

    • Date

• Using black and white film

How to preserve fingerprints?

• Photography

• Lifting

  • Apply fingerprint[rint tape, smooth air bubbles, lift tape, place on blank card

  • Curved surfaces  gelatin…

What is AFIS?

Automated Fingerprint Identification System

• Computerized fingerprint record comparison system

• In Canada, evidentiary prints loaded into AFIS program to search for possible matches

  • If generated, fingerprint examiner must manually confirm the “match”

Checking that a number of points areidentical on both the evidentiary printand the reference prin

What are the class characteristics of fibres?

• Colour

• Striations on the fibres’

• Cross-selectional shapes