Categorie: Tutti - forensics - evidence - investigation - contamination

da Marina Sabetti-Franklin mancano 4 anni

523

Forensic Sciences

The field of forensic sciences plays a crucial role in criminal investigations by applying scientific principles to legal matters. Crime scene investigation is a fundamental aspect, focusing on the collection and examination of physical evidence such as blood, ammunition, and drugs.

Forensic Sciences

Student ID:1006162073

Marina Nicole Sabetti-Franklin

Forensic Facial Approximation

Inconclusive Data

Skin Blemishes
Hair Style
Eye Colour
Hair Colour
Possible Comparison
4.Establish Positive ID
3.Generate new Leads
2.Present Likeness to Public
1.Create a likness of individual
Positive Comparison
Orthidontal
Radiological
DNA

Target Audience

Primed
Seeking missing person ex.family
Casual
May know individual in passing

Methods

Digital
American
Combination/Manchester

Facial Land Marks

Nose
Anterior nasal spine
Nasal aperature
Pro nasally
Lips
Kelly and Kelly
Transitional Zone
Vermillion Boarder
Labial Commissar
Eyes
Anterior-posterior Placement
Maylar/Witnall's Tubricle
Superior Torssal Plate
Medial Canthal Tendon
Skin
(etc...)
Nasospinale
Nasale
Nasion
Glabella
Super glabell

Crime Scene Reconstruction

2Analysis

Cast-Off Stains
Motion Capture Suit and Laser Scanner
Suspect Height
Laser Scanner and CCTV Camera Technology
Shooting Scene
Laser Scanner and Bullet Trajectories
Blood Stain
Laser Scanner and Area of Origin Analysis

3.Visualization

Virtual Reality
3D Print
Interactive 3D Models
Virtual Tours
3D Rendering
2D Plan Drawings

1.Documentation

3D Technology
Video/Photogrammetry
Drones
Laser Scanner

Phase Shift Meathod

Time of Flight Meathod

Structured Light Scanner
3D Microscope
Manual
Sketches
Strings
Tape Measures

Fingerprint Analysis

Examination

Further Visualization Methods
Recover Lift
Infrared Photography
Photo Editing
Gel Scan
Vacum Metal Deposition Chamber
Substrate
Semiporous

Tape

Tape Glo

Sticky Side Powder

Non-Porous

Cyanoacrtlate (Glue Fuming)

Adrox

UV Light

Rhodamine 6G

Trace Laser

Basic Yellow

Blue Light

Porous

Powders

Nano Flourescent

Fluorescent Magnetic

Grey

Chemical

Ninhydrin

1,8 Diazafluren-9-One

1,2 Indandione

Matrix
Foreign Materials
Sebaceous Sweat
Eccrine Sweat
Level Of Detail
Level 3

Width

Edge Shapes

End Shapes+Angles

Pores

Level 2 (Minutiae)

Enclosure

Bifurcation

Ridge Ending

Short Ridge

Ridge Unit

Level 1 (Overall Flow)

Focal Points

Delta

Core

Pattern Types

Whorl

Loop

Arch

Orientation

ACE-V
Verification

Inconclusive

Exclusion

Conclusion

Evaluation
Comparison
Analysis

Fingerprint

Both the pattern found on human skin(friction ridges) as well as the mark left behind on a surface from making contact with this skin pattern.

Structure
Layers

Dermal Papillae

2 layers of skin pegs in-between the dermis and epidermis holding the epidermis in place.

Epidermis

Thin outer layer consisting of cells that take a month to shed.


Has 5 primary layers:

-Stratum corneum

-Stratum lucidum

-Stratum granulosum

-Stratum spinosum

-Stratum Basal/basale


The basal layer is directly in contact with the dermal layer and iis where new cells are formed.

Stratum Basal

Stratum Spinosum

Stratum Granulosum

Stratum Lucidum

Stratum Corneum

Dermis

Thick inner layer

Units fuse together during fetal growth
Each unit has a sweat gland and pore
Made up of ridge units
Characterisitics
Many nerve endings
Minimal pigmentation
No hair
More sweat glands per sq in
No sebaceous glands
Anatomy of Friction Ridges
Allows for traction
Found on all primates
Also known as 'Volar'
Four Premises of Friction Ridges
4.Vary within limits, allowing for classification
3.Unique to every person
2.Never change unless scarring, disease, or death
1.Develop prior to birth
Fingerprint Composition

The natural secretions on the surface of skin mixed with other materials like sweat and foreign materials such a dirt can leave behind an impression/deposit upon contact causing a replication of the fingerprint.

Impression Mark

The replication of a fingerprint using an ink-pad and paper for later identification.

Shooting Scene Examination

Blood Stain Pattern Analysis

Point of Origin

Visualization Meathods
Computer Modeling
String Meathod
Locating
3.Calculate Angle of Impact
2.Look for Area of Convergence
1.Look for Directionality

Blood

Visualization/Enhancment
Simple Transfer

Alginate Lift

Chemicals

Leuco Crystal Violet

Amido Black

Hungarian Red

Properties
Viscosity

4x more than blood

Surface Tension
Composition
Buffy Coat
Erythrocytes
Plasma

Classification

Types
Spatter

Impact Pattern

Patterning due to Fire Arms

Expirated

Cast-Off

Sessation Cast-Off

Projected

Transfer

Wipe

Swipe

Simple Contact

Passive

Saturation Pattern

Flow Pattern

Pool Pattern

Splash Pattern

Drip Pattern

Drip Trail

Drip Stain

Exceptions
Voids
Blood Clotting
Decomposition Over Time
Drying Over Time
Insect Interferance
Dilution

Foot Wear Analysis

Impression

When an object or material has retained the characteristics of other objects or materials that have been pressed against them.

3D
Identification

Occurrence # /adress

Date of Cast

Officer's Initials/Badge

Footwear #

(FW#)

There may be multiple foot prints located at the scene thus each must be numbered.

Casting

Allows you to create a replica of the impression or object to bring into court to show the judge and jury.


Impression is casted after proper photography is completed and potential debris is removed.

A release agent may also be applied to help remove the cast (ex.parting powder)


After fully cured the mast needs to be leaned using a course brush.

Dental Stone

Can be casted on multiple surfaces.

After pouring you must wait 30min before removing and another 24 hours before fully cured.

Sulphur

Only used to cast impressions in snow.

After heating up and pouring over an impression one would usually pour dental stone over top for durability due to sulphur being very fragile.

4.Apply Contrast

In certain scenarios ex.snow, the impression may not be visible and thus it is necessary to apply snow-print wax or primer paint in-order to see the impression.

Could increase the melting rate of the impression thus needs to be done quickly or under shade.

Place light at a 35-45 degree angle.

2.Place Scale

Scale must be level with the bottom of the impression.(Ex Recess the L-scale into dirt instead of leaving it on the surface to get the proper depth perception)


Insure that you never place scale or anything over the impression as it obstructs the evidence.

1.Set up Tripod

Just like 2D tripod should be parallel to the impression.

Dealing with length width and depth.


Thus, you cant just involve photography but also must use a cast.

Sand

Dirt

Mud

Slush

Snow

2D

Usually footwear or tire tracks.

Recovery

Gelatin Lifter

Works for both a dried wet origin impression and a dry dust impression.


A gelatin layer covered by a clear acetate with a black or white backing. Due to it's extra weight the gelatin sinks onto the floor more than mylar and thus can pick up more of the substrate.

Can be used for lifting fingerprints, footwear impressions and even blood impressions.


Must be photographed immediately after being lifted due to the layer of clear acetate applied over the impression. This acetate layer prevents you from seeing the impression without peeling the layer back off. Every-time you do so you are risking damaging your impression.


(Is a laterally reversed image thus must be corrected)


Is a one time use but can be preserved.

Electrostatic Lifter and Mylar Film

Use mylar and apply an electrostatic charge to the foil which takes the dust and cause it to be sucked up and adhered to the mylar.


Easy to use and can be reused but very expensive.

Fingerprint Powder and Lifting Tape

Only works with a dried wet origin impression.

Ex. if you try to use this method with an impression left from a dusty shoes it will not work as the dust will be wiped off.


Usually only used on glass and plastic.

Fingerprint tape can stabilize an impression onto the surface in-order to move the substrate(ex.glass fragment) instead of trying to remove the impression from a substrate.

Photography

Use Tripod in-order to control shudder speed and depth of field.

Position on a levelled surface to not have it tip or fall over

Insure the tripod is parallel to the impression to get accurate scaling of the impression.


We are photographing in relation to the impression. NOT THE GROUND. Thus if the impression is on a hill and we position it to the ground the image will be distorted.

Use Tape

Finding

4. Mark Location

To ensure remembering the location and to not disturb the evidence, mark both ends of the impression.

3.Use Oblique Lighting

Light held at a low angle.

2.Darken Room

1.Examine Floor

Dust Foot Print, Finger Print
Mud, Blood, Paint
Locations

Check all areas within the scene in which we know someone has been.

Point of Exit

Disturbed areas

Points/attempted points of Entry

Route to Scene

Forensic Sciences

Principals and methods used in matters related to the law.

Type in your name

Crime Scene Investigation

Contact information

Any CV or résumé needs to contain your contact information. This way, recruiters can get in touch with you.

Specialists
Forensic Scientist

Firearm

Examining potential impressions to identify if a particular firearm or tool was used at the scene of a crime

Documents

identifying if a document has been altered or not

Toxicology

testing of biological and non-biological samples with respect to drugs and alcohol

Chemistry

Testing for physical trace evidence and change in physical properties

ex. at a scene of an explosion they can identify if there is any useful evidence

Biology

Testing of DNA and bodily fluids

Forensic Identification Officer

(FIO)

Involved during more severe crimes ex.homicide

Processes the scene more thoroughly.


8-10 week intensive training course + additional specialized training

Scene of Crime Officer

(SOCO)

Processes and documents less complex crime scenes.

Usually have additional specialized training and photography skills.


ex.

Investigating Officer

The first general officer on the scene.


They will secure the scene to prevent:

Conrdoned Area

Sealed area in which evidence may be found

Path of Contamination

pathway where authorized individuals can enter and exit the scene

Locard's Principal of Exchange

When an object comes in contact with a surface there will always be an exchange of material.

Physical Evidence
Examination of Evidence

1.Identify

Is there a change in state or chemical composition?

ex. the car has it's paint chipped.

2.Compare

ex.Most paint chips have 5 layers where this one has 8.

3.Conclusion

ex.The car must have come from this specific auto shop.

Blood,Semen,Saliva
Ammunition, Paintchip, Drugs