Test #1 Flashcards
Forensic Science vs. Forensic Identification
1) - natural and physical sciences - theory based - bench scientists 2) - applied science - based on scientific methodology, but investigative based
CSI vs. FIS
1)
- crime solved in 60 mins
- tests always work and result in a match
- suspects often plant false evidence
- exotic locations with great vehicles
- the do it ALL
2)
- crime is never solved in 60 mins
- tests often prove negative
- false leads are few and usually easily spotted
- bug infected rooming houses
- require physical match
- we enjoy our work
What is a fingerprint?
An impression left on a surface by the friction ridges of the skin on your fingers
What is a live scan?
10 rolled fingerprints taken from criminals
What materials are fingerprints often found in?
Sweat, dirt, blood, paint, etc.
What is ridgeology?
The study of uniqueness of friction ridge structures and their use for personal identification
Where can friction ridges be found?
Fingers, palms, and soles
Does dermal papillae change throughout life?
No
Dermis vs. Epidermis
1) Thick foundation
2) Thin outer layer
- attached by double row of dermal papillae
What is a familial tendency?
Similarity of pattern sequence but never the same
What are the 4 premises?
1) the form during fetal development
2) they don’t change
3) they are unique
4) they are classifiable resulting in searchable database
What was used before fingerprinting?
Anthropometric measurements
What are the 3 basic patterns?
1) Arch
2) Loop
3) Whorl
What are the relationships between fingerprint pattern, and volar pad tension & pressure?
1) High-centred Pads = Whorl = High Pressure
2) Med-centred Pads = Loop = Med Pressure
3) Low-centred Pads = Arch = Low Pressure
What are the 3 levels of fingerprint analysis?
1st) Pattern
2nd) Minutiae
3rd) Ridge edges and pores
What are 3 anomalies used to identify fingerprints?
1) Ridge ending
2) Bifurcation
3) Ridge dots
Do interdigital or hypothenar and thenar pads form first?
Interdigital pads for first
What happens at 6 weeks (Volar pads)?
Volar pad starts forming on palm
When do volar pads start to regress on the palm and fingers?
1) 10 weeks
2) 11 weeks
What happens at 8 weeks (Volar pads)?
Fingers separate and volar pads form on the fingers
What happens at 10 weeks (Volar pads)?
Digital pads are distinct
What happens at 12 weeks (volar pads)?
Friction ridges start to develop in the basal layer, and volar pads regress
A ridge is referred to as a _______?
A furrow is referred to as a _______?
1) Hill
2) Valley
Why do we have friction ridge skin?
To improve grip and prevent slippage
What does each ridge have and why?
Single row of pores, used as openings for sweat gland ducts
Will damage to the epidermis have an effect on the fingerprint pattern?
No, but damage to the dermis will
What happens in weeks 5-7 for development of friction ridge skin?
- Fingers elongate
- Cartilaginous bones form
What happens in weeks 7-11 for the development friction ridge skin?
- Volar pads form
- Major creases form
What happens in weeks 11-17 for the development friction ridge skin?
- Volar pads regress
- Primary ridges form
- Sweat glands, ducts, and pores form
What happens in weeks 17-24 for the development friction ridge skin?
- Primary ridge development stops
- Secondary ridges form between primary ridges
What happens in weeks 24-27 for the development friction ridge skin?
- Friction ridges are fully developed in their final arrangement
- Dermal papillae form
- Basement membrane joins epidermis to dermis
Who developed the fingerprint classification system?
Sir Edward Henry
What are the 4 focal points for fingerprint identification at the 1st level?
Cores, Deltas, Scars, Creases
What did Sir Francis Galton propose?
Using fingerprints as a means of identifying criminals
What are the 4 individual ridge path/events used for identification at the 2nd level?
Ending ridges, Bifurcations, Dots, Islands
What are the 4 ways of identification using size and shape of pores and ridges at the 3rd level?
Pore sizes, End shapes and angles, Edge shapes, Width of ridge
What does forensics mean in latin?
Relating to or dealing with application
Who developed the 1st level of detail, and what is identifiable? What instrument is used?
- Henry
- Ridge flow and pattern, Core, Delta
- Visible to naked eye
Who developed the 2nd level of detail, and what is identifiable? What instrument is used?
- Galton
- Ridge endings, Bifurcations, Islands, Lakes, Dots
- Magnifying glass
Who developed the 3rd level of detail, and what is identifiable? What instrument is used?
- Ashbaugh
- Location of pores in the ridges, shapes of the edges of the ridges, how ridges effect each other
- Microscope
What are the five basic characteristics that combine to produce ridge patterns?
- Ridge Ending
- Bifurcation
- Ridge Dot
- Short Ridge (Island)
- Enclosure (Lake)
What are fingerprint secretions composed of?
Sweat, Sebum, Lipids, and/or Foreign materials picked up by the hands
What are the 3 sources of natural secretions on the human body?
- Eccrine sweat glands
- Sebaceous sweat glands
- Apocrine sweat glands
What is eccrine sweat composed of?
- 98.5% to 99.5% water
- 0.5% to 1.5% solids
What is sebum?
Secreted by sebaceous glands, found in areas covered by hair
What does sebum consist of?
Saturated fats, waxes and squalene, which makes it have a high affinity to fingerprint powders
What are the 5 factors affecting fingerprint secretions and concentration?
- Rate and duration of sweating
- Dietary habits
- Age
- Gender
- Stress
What 3 factors affect the life-span of a fingerprint?
- The person (genetic factors)
- The surface
- The environment
How can you tell the age of a fingerprint?
There is no accurate way of determining, unless there is something to corroborate it
- Time/dated receipt, newspaper, video surveillance, eyewitness account, etc.
What is a latent fingerprint?
A print that is invisible to the naked eye, that is caused by transfer of body perspiration or oils present on finder ridges to the surfaces of an object
What is a patent fingerprint?
Composed of secretions and foreign materials (ie. Blood, Grease, Dirt etc.) and transferred from the finger to the surface. Visible to the naked eye, they require minimal development and must be photographed
What it a plastic or mold impression?
3D impression in soft material:
- Chocolate
- Cheese
- Putty
What is the general rule for fingerprinting?
Fingerprints may be found on any surfaces with sufficient size and surface continuity to disclose the necessary ridge characteristics in sequence
What is the fingerprinting process?
1) Powder/process
2) Label/mark
3) Photos (overall, midrange, macro)
4) Notes - memo book/acetate
5) Lift and retain
What are the two categories of surfaces?
- Porous
- Non-porous
What are the methods used for porous surfaces?
- DFO (amino acid reagent)
- Ninhydrin (amino acid reagent)
- Physical Developer/Zinc Chloride
- Iodine fuming with silver plates (skin)
What methods are used for non-porous surfaces?
- Cyanoacrylate (superglue fuming)
- Vacuum Metal Deposition
- Iodine Fuming (fat/grease deposits)
- Camphor Smoke (plain or galvanized metal)
How is fingerprint identification established?
Through the continuous agreement of friction ridge formations, in sequence, having sufficient uniqueness to individualize
What does ACE-V stand for?
Analysis
Comparison
Evaluation
Verification
What are the 3 conclusions in evaluation?
- Identification (same source)
- Exclusion (not same source)
- Inconclusive
What did Daubert do?
Examined the admissibility of scientific evidence, and determined that the judge must screen scientific evidence to determine that it is relevant and reliable
What are the Daubert Guidelines?
1) Whether the theory and technique have been tested
2) Whether the theory and technique have been subjected the peer review and publication
3) Known or potential error rate
4) Existence and maintenance of standards
5) General acceptance within relevant scientific community
What is RUVIS?
Reflected Ultra Violet Imaging Systems
Can locate prints on most non-absorbent surfaces
What are the brushes used for developing fingerprints made out of?
Camel hair, fibreglass, or magnetic wand
Iodine Fuming:
- Oldest method of chemically visualizing latent prints
- Solid crystal that turns to vapour when heated
- Occurs in closed cabinet
- Not permanent & must be photographed immediately
- If covered with cellophane tape, will be usable for several months
- If sprayed with 1% of starch in H2O, print turns blue and lasts for several weeks, to several months
Ninhydrin:
- Forms chemical reaction with amino acids and turns it purple-blue
- Commonly sprayed on to porous surface from aerosol can
- Appear in 1-2 hours, weaker prints 24-48 hours
- Development can be hastened if treated specimen is heated 80°C - 100°C
Physical Developer:
- Dip item into developer and leave on for about 30-90 seconds then rinse with distilled water
- Effective on porous articles that may have been wet at one time
Cyanoacrylate:
- For use on metals, electrical tape, leathers, plastic bags
- Fumes created when superglue is placed on absorbent cotton treated with NaOH
- Or by being heated
- Fumes from glue adhere to latent print after being enclosed in a chamber
What are the steps of developing prints?
1) Photo of print
2) Photo of surroundings
3a) Small object - cellophane fingerprint to preserve
3b) Large object - lifting
What are methods of lifting impressions? How do these methods work?
- Tape (only if small enough to be covered by tape)
- Electrostatic lifting device (mylar film placed on dust mark, then high voltage electrode placed in contact with film. Charge difference develops between film and surface so the dust attaches to film)
What are some methods of casting impressions?
- Class 1 dental stone
- Wax and dental stone (used for snow)
What is a General Characteristic?
An unintentional or unavoidable characteristic that repeats during the manufacturing process and is shared by one or more shoes or tires
What is an Accidental (individual) Characteristic?
The result when something is randomly added to or taken away from the original structure of the shoe or tire that either causes or contributes to making that shoe or tire unique
What’s the difference in conclusions of Fingerprints vs. Footwear?
Fingerprint conclusions are more definitive
Footwear conclusions have many more variables
- still in production
- years produced
- how long since production ended
- how many were made
What are some methods of detection or enhancement of impressions?
- Light (ambient, white, oblique, ALS, laser)
- Fingerprint Powder
- Chemistry (blood reagents, bromophenol blue, potassium thiocyanate
What are some methods of collecting 2D footwear?
- Physical removal of surface
- Polyvinylsiloxane
- Gel Lifter
- 4” Tape
- Dental Stone
What is 3D forensics?
The use of 3D technologies that assist with documentation, analyzing, reconstruction and visualization of evidence
3D Reconstruction vs. Recreation
1) Based on physical evidence put together to prove something to be analyzed
2) Could be based on physical evidence, relies on witness testimony, non-physical evidence for demonstrative purpose (creative work)
What are some uses of 3D technology?
- Graves
- Matching tools with tool mark
- Virtual autopsy
- 3D impressions
- Suspect height analysis
- Evidence
- Blood stains
- Shooting to back trajectory
How do you remove subjectivity?
Software do not understand human subjectivity
What are some 3D technologies?
- 3D microscope (for small things)
- Structured light scanners (throws a fridge pattern on an object to find specific points of interest)
- Structure dots (infrared projection, infrared camera, colour camera, can be used for tracking)
- Hand held scanner
What is photogrammetry and what does it do?
- Old technology used when cameras were first invented
- Put camera on a balloon and took photos from the air
- Can create 3D models with many photos
- Image straightening (fixes perspective)
What does a laser scanner do?
- Captures millions of points and colour using phase based camera (sends signals, reads wavelengths)
What other technology can be used with 3D?
- Thermal technology
- 3D printing
What are the 3 things to remember from the Library Presentation?
- DONT PAY
- GET HELP
- CITE YOUR WORK
Scholarly Journal Articles vs. Peer Reviewed Articles?
1) Written by experts for academic professional audience
2) 3 expert reviewers or more, refereed
What does white granular powder work best on?
Non-porous surfaces
Why is black magnetic powder preferred?
Because it’s less messy
What is the Knapp method?
Using dental stone to lift a powdered fingerprint
When should dental stone be used to lift a fingerprint?
When it’s on a textured surface
How do you use camphor smoke to develop fingerprints?
- Ignite it
- Hold object over flame
- Wipe away excess soot to expose prints
What is casting material (polyvinylsiloxane) for?
- Used to fingerprint textured surfaces
- Used to fingerprint cadavers
- Used to make impressions of tool marks
How does cyanoacrylate work?
Polymerizes where the fingerprint is
What does anthropology mean?
What it means to be human
What do forensic anthropologists assist in?
- Locating human remains
- Search organization
- Knowledge of body dumpsite
- Mapping and recovering human remains
- Proper excavation techniques
- Analyzing human remains
- Forensic significance, taphonomy, time since death, trauma, identification
- Presenting results in court
What are the 3 approaches of locating remains?
1) Remote sensing (aerial photography, thermal imaging)
2) Geographical methods (ground penetrating radar, metal detector)
3) Ground search (line search is most common)
What are line searches?
- People side to side, advance in unison
- When potential evidence is found the line stops and it is documented
- Depending on the terrain, shoulder to shoulder, arms width apart, hands and knees
What are the benefits of line searches?
- Thorough
- Usable on almost any terrain
- Cost effective
- Able the augment with probes, cadaver dogs, heavy machinery
What are the objectives of mapping and recovering remains?
- Proper documentation and preservation of evidence
- Construction horizontal and vertical profiles
- Establish context
- Interpret significance
- Maintain chain of evidenxe
What is forensic significance?
Do the remains have a role to play in a medicolegal investigation?
- Archaeological remains
- Cemetery (disturbed remains)
- Teaching skeletons
- Religious practice
Are all examples of…
Non-forensically significant remains
A biological profile includes estimations of…?
- Sex
- Age
- Ancestry
- Stature
Biological profile also includes possible trauma, and pathological conditions
How to determine sex…?
- Fundamental physiological differences between males and females
How to determine age…?
- Use of how bone changes with time to estimate age
- Porosity, density, and specific types of newly formed bone can be used
How to determine ancestry…?
- Some skeletal characteristics have been linked to certain ancestral groups
- Impossible to state conclusively because of complex admixture
How to determine stature…?
- Possible from long bone dimensions
What are the 3 types of traumas?
- Blunt force
- Sharp force
- Gunshot
Liquid blood will behave…
According to the laws of physics
When is blood spatter analysis used?
- Homicide
- Non-homicide death investigations
- Serious assaults
- Sexual assaults
- Serious industrial accidents
What information can blood spatter analysis provide?
- Impact locations
- Number of impacts (min)
- Object or mechanism used to creat pattern
- Movement of people and objects during bloodshed
- Movement of people and objects after bloodshed
- Sequence of events
What did Hans Gross do?
- Coined the term “criminalistics”, the scientific study of crime
- Described importance of blood marks and traces of blood in investigation
What did Eduard Piotrowski do?
Bashed rabbits with hammer and recorded blood spatter
What did Victor Balthazard do?
- Relationship between length and width of spatter stain
- Area of origin
What did Paul Kirk do?
Provided blood spatter analysis evidence in Sam Sheppard homicide case
What does the understudy of training program consist of?
- Classroom study
- Lab based experiments
- Scene attendance & exam with mentor
- Certification process
What are the limits for evidence to be allowed in court?
- Relevant to case
- Necessary to assist trier of fact
- Absence of exclusionary rule
- Qualified expert
Properties of blood talked about in lecture:
- Approximately 5L in avg. adult
- 55% Plasma
- Non Newtonian fluid (viscosity changes)
- Slow blood loss is tolerated better than rapid blood loss
- Blood is approximately 4x more viscous than water
- Elastic property of the surface of blood makes it contract to most efficient shape (sphere)
What % of blood loss can the body tolerate without significant symptoms?
15%
What is the difference between 30% and 40% blood loss?
1) Mild symptoms
2) Life threatening
Is the ability of blood to reproduce specific patterns affected by:
- Age
- Sex
- Alcohol/drug use
- Disease process
No
What are the 3 types of bloodstains?
- Passive
- Transfer
- Spatter
What are some exemptions for bloodstains?
- Dilution
- Insect activity
- Drying
- Clotting
- Decomposition
What are passive patterns?
Creates or formed by the force of gravity acting alone on blood
What are the 5 examples of passive patterns (drip)?
- Splash
- Satellite
- Pool
- Flow
- Saturation
What is a transfer pattern?
Resulting from contact of blood to other surfaces
What are the 3 types of transfer patterns?
- Contact
- Swipe
- Wipe (usually found in combination with swipe)
What are spatter bloodstain patterns?
Resulting from a drop of blood dispersed through air from impact
What are the 4 types of spatter patterns?
- Projected
- Cast off (tangential to motion)
- Expirated
- Mist
Can be calculated because NRG vs. Stain size is directly proportional
What is an impact pattern?
Force traumas via objects
What is Balthazard’s formula?
Arcsin width/length = angle of impact
What is the area of origin?
3D location from which spatter originated
What methods can be used to determine area of origin?
- String method
- Back track suit (computer programs)
- Hemospat software
- 3D rendered images
