BLOODSTAIN AND FOOTWEAR
Q: Why is footwear evidence referred to as "the forgotten evidence"?
A: It is often overlooked for its potential evidentiary value in investigations.
Visual Evidence
Q: What role does visual evidence play in court?
A: It can be presented to juries to support the investigation.
Footwear Impressions
Q: What are footwear impressions?
A: Two- or three-dimensional prints left by shoes.
Reasons Footwear Evidence is Overlooked
Q: Why is footwear evidence often overlooked?
A:
Lack of training in proper techniques for searching, photographing, and preserving evidence.
The evidentiary value of footwear impressions is not understood.
Lack of education in comparing footwear and writing reports.
Lloyd Homicide Investigation
Q: How was footwear evidence important in the Lloyd homicide investigation?
A:
Footwear impressions were found in snow at the scene.
Tire track impressions were linked to a specific make of vehicle.
Suspect Williams was found driving that make of vehicle and wearing the same boots as those found at the scene.
O.J. Simpson Trials
Q: What was a key footwear-related evidence in the O.J. Simpson case?
A: Bruno Magli shoes were key evidence in his civil lawsuit.
Information from Footwear
Q: What important information can footwear provide?
A: It may indicate the number of suspects involved.
Class Characteristics
Q: What are class characteristics in footwear evidence?
A: Manufactured traits that are repeated across multiple shoes.
Accidental Characteristics
Q: What are accidental characteristics in footwear evidence?
A: Random traits dependent on shoe usage, such as wear and damage.
Gelatin Lifter
Q: What is a gelatin lifter used for?
A: To lift prints from various surface types.
Electrostatic Dust Print Lifting
Q: How does electrostatic dust print lifting work?
A: A charged plastic film creates electrostatic adhesion, lifting dust prints from surfaces.
Casting
Q: What is casting used for in footwear evidence?
A: To record three-dimensional footwear impressions.
Two-Dimensional Impressions
Q: What are two-dimensional impressions?
A: Visible impressions left on flat surfaces.
Locating 2D Impressions
Q: Where should you look for two-dimensional impressions?
A:
Movement within the scene.
Points of entry and exit.
Disturbed areas.
Three-Dimensional Impressions
Q: What are three-dimensional impressions?
A: Impressions with depth, length, and width.
Oblique Lighting
Q: What is oblique lighting used for?
A: To enhance the visibility of impressions.
Closeup Photography
Q: Why is closeup photography important for impressions?
A: To capture detailed images with a scale for comparison.
Flash Sync Cord
Q: What is a flash sync cord used for?
A: To synchronize flash photography for impression documentation.
Photographing 3D Impressions
Q: How should 3D impressions be photographed?
A:
Camera aligned with the impression.
Scale level with the bottom of the impression.
Use oblique lighting at 45 degrees.
High depth of field (F18-22).
Take photos from multiple angles.
Impression Enhancement
Q: What is impression enhancement?
A: Techniques used to improve the visibility of impressions.
Snow Wax
Q: What is snow wax used for in impression casting?
A: To protect impressions in snow during casting.
Paint in Impressions
Q: Why is paint used in impressions?
A: To color patterns, making them more visible.
SICAR
Q: What is SICAR?
A: Shoeprint Image Capture and Retrieval system for footwear evidence.
Tire Track Impressions
Q: What are tire track impressions?
A: Two- or three-dimensional impressions left by tires.
Tire Track Collection Techniques
Q: How are tire tracks collected?
A: Through photography and casting.
Tire Track Notes
Q: What should be included in tire track notes?
A:
Where found (inside/outside).
Direction of travel.
Impression details (pattern).
Substrate (dirt, snow, roadway).
Preservation method (photos, casting).
Luminol
Q: What is luminol used for in crime scene investigations?
A: To detect blood traces by reacting with iron in hemoglobin, emitting a blue light.
Bloodstain Shape
Q: What does a bloodstain's shape indicate?
A: The direction of travel of the blood.
Area of Convergence
Q: What is the area of convergence in blood spatter analysis?
A: The two-dimensional point where bloodstain trajectories intersect.
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Area of Origin
Q: What is the area of origin in bloodstain pattern analysis?
A: The three-dimensional location where blood originated.
Impact Spatter
Q: What is impact spatter?
A: Blood droplets created when an object impacts a source of blood.
Forward Spatter
Q: What is forward spatter?
A: Blood that travels away from the source of impact.
Back Spatter
Q: What is back spatter?
A: Blood projected backward from the source of impact.
Low-Velocity Spatter
Q: What causes low-velocity spatter?
A: Forces under 5 ft/sec, typically gravity, minimal force, or an object splashing in a blood pool. Droplets are generally >4 mm.
Medium-Velocity Spatter
Q: What causes medium-velocity spatter?
A: Blunt force trauma with forces between 5-25 ft/sec. Associated with injuries such as beatings.
High-Velocity Spatter
Q: What causes high-velocity spatter?
A: Forces over 100 ft/sec, often from gunshot exit wounds. Droplets are typically <1 mm.
Gunshot Spatter
Q: What is gunshot spatter?
A: Blood spatter caused by gunfire, often with blowback patterns.
Cast-Off Spatter
Q: What is cast-off spatter?
A: Blood flung from a moving object, such as a weapon.
Arterial Spray Spatter
Q: What is arterial spray spatter?
A: Blood spurts resulting from an arterial injury.
Expirated Blood
Q: What is expirated blood?
A: Blood expelled from the respiratory system, often mixed with saliva or mucus.
Void Patterns
Q: What are void patterns in bloodstain analysis?
A: Areas lacking blood spatter due to an obstruction.
Transfer Patterns
Q: What are transfer patterns?
A: Blood patterns created when a bloodied object comes in contact with another surface.
Flow Patterns
Q: What are flow patterns?
A: Blood movement influenced by gravity.
Pools
Q: What are pools in bloodstain analysis?
A: Blood that collects in a level, undisturbed area.
Drip Trail Patterns
Q: What are drip trail patterns?
A: A series of drops forming a line or path, showing movement.
Surface Effects on Blood Spatter
Q: How do harder, less porous surfaces affect spatter?
A: They result in less spatter.
Q: How do rough surfaces affect bloodstains?
A: They can create irregularly shaped stains with serrated edges and satellite spatter.
Tire Track Database
Q: What is the RCMP tire track database?
A: A database maintained by the RCMP in Ottawa, with approximately 1,100 tires on file, used to link tire tracks to vehicle types.
Footwear Notes
Q: What should be included in footwear notes?
A:
Location where found (inside/outside).
Direction of travel.
Impression details (pattern, depth).
Substrate (e.g., dirt, snow, tile).
Preservation method (photos, casting).
Development or enhancement techniques used (e.g., fingerprint powder, spray paint).
Number and types of impressions.
Elimination footwear from witnesses, victim, or suspect.
Tire Track Measurements
Q: What measurements are important for tire track analysis?
A: Width, turning diameter, and wheelbase.
Superimposition in Footwear Analysis
Q: What is superimposition in footwear analysis?
A: Placing a clear acetate copy of a test impression over the crime scene impression to compare characteristics.
Leucocrystal Violet (LCV)
Q: What does leucocrystal violet (LCV) do?
A: Enhances blood visibility on surfaces by turning deep purple.
Direction of Blood Origin
Q: How is the direction of blood origin determined?
A: By the shape of the bloodstain, with the pointed end indicating the direction of travel.
Impact Angle Measurement
Q: How is the impact angle of blood determined?
A: By measuring the degree of circular distortion in the stain.
Victim Position
Q: What can blood patterns reveal about victim positioning?
A: The location or position of a victim when the bloody wound was inflicted.
Movement of Bleeding Individuals
Q: How is the movement of a bleeding individual traced?
A: Through the pattern and directionality of blood trails or spatter.
Approximate Location of Assailant
Q: How can bloodstains indicate the location of an assailant?
A: By analyzing bloodstain patterns and points of convergence.