Week 9: Crime Scene Investigation Footwear and Bloodstain Evidence

Today’s Lecture Focus

  • Topics Covered:

    • Footwear evidence

    • Case examples

    • Background on documentation

    • Photography techniques

    • Collection techniques

    • Gelatin lifter

    • Casting methods

    • Electrostatic lifting

    • SICAR database (Shoeprint Image Capture and Retrieval)

    • Bloodstain evidence

    • Background on bloodstains

    • Documentation methods

    • Photography techniques

Footwear Evidence Details

  • Description:

    • Often referred to as the "forgotten evidence" in crime scene investigations.

    • Significant potential as evidence that can be utilized in court and presented to a jury.

  • Benefits of Footwear Evidence:

    • Identification of type and make of shoe.

    • Approximate size of shoe.

    • Potential identification of number of suspects.

    • Pathway in, through, and away from a crime scene can be established.

    • Possible reconstruction of the sequence of events concerning the crime.

Reasons for Overlooked Footwear Evidence

  • Reasons for Overlooking Evidence:

    • Inadequate training in techniques for searching, photographing, and preserving footwear evidence.

    • Misunderstanding the evidentiary value of footwear impressions.

    • Insufficient education regarding the comparison of footwear and report writing.

Case Study: Lloyd Homicide Investigation

  • Key Findings:

    • Footwear impressions found in snow at the scene of the investigation.

    • Tire track impressions were also found in the snow.

    • Tire impressions were associated with a specific make of vehicle.

    • The suspect, Williams, was later a subject in a police checkpoint while driving the identified vehicle.

    • Williams was discovered wearing the same boots he had been observed wearing at the crime scene.

    • The footwear and tire track evidence played a critical role in the investigation.

O.J. Simpson Trials Analysis

  • Criminal Trial Details:

    • Duration: 11 months.

    • O.J. Simpson was in custody for 474 days.

    • Verdict reached in 4 hours; found not guilty on two murder charges.

  • Civil Trial Details:

    • Included 101 witnesses and took 41 days of testimony.

    • Simpson found guilty of "wrongful death."

    • Ordered to pay $33.5 million to the families of the victims.

Bruno Magli Footwear Evidence

  • Importance of Footwear:

    • Key pieces of evidence were the Bruno Magli shoes.

    • Size of shoes: 12 (European 46 sole).

Footwear Impressions Explained

  • Types of Impressions:

    • Can be both 2D and 3D impressions.

    • Proper scale must be aligned with the bottom of the impression for accurate depiction.

    • Tripods are necessary for close-up photography.

  • Common Issues:

    • Many impressions are typically partial; recovery of all impressions is crucial.

    • Footwear impressions can yield information regarding the number of suspects involved.

Characteristics of Footwear

  • Class Characteristics:

    • Manufactured characteristics that are either intentional or unavoidable and repeat in manufacturing.

    • Example: specific tread patterns.

  • Accidental Characteristics:

    • Random features; size, shape, and orientation dependent on usage.

    • Often associated with wear from being used.

Footwear Collection Techniques

  • Gelatin Lifter:

    • Sheets of rubber with low-adhesive gelatin to lift prints from porous, rough, curved, and textured surfaces.

    • Commonly used in conjunction with fingerprint powders.

  • Electrostatic Dust Print Lifting Device:

    • Works by charging a plastic film placed over the dust print, creating electrostatic adhesion that retrieves the print.

  • Casting Techniques:

    • Used to record three-dimensional impressions, often involving dental stone.

    • Particularly effective for impressions in snow, sand, or soil.

Locating Impressions

  • Two-Dimensional (2D) Impressions:

    • Examine potential movement within the scene, entry and exit points, and disturbed areas.

    • Most visible impressions will likely be located on the floor and can be enhanced using oblique lighting.

  • Three-Dimensional (3D) Impressions:

    • Typically found outside or at entry/exit points.

    • Need to consider depth as well as length and width in measurements.

Photography Techniques for Footwear Evidence

  • Overall and Mid-Range Photos:

    • Initial shots should be taken without a scale, followed by close-up shots featuring a scale for reference.

  • Close-up Photography:

    • Utilize a tripod; ensure camera is positioned in parallel alignment with the impression.

    • Include a rigid scale in every photograph accurately positioned next to the footwear impression.

  • 3D Impressions:

    • Capture with the camera level with the impression; emphasize oblique lighting for best results.

Bloodstain Evidence

  • Background on Bloodstains:

    • Bloodstain pattern analysis (BPA) is critical for understanding crime scene details.

    • Analysis should ideally be conducted on-site to comprehend spatial relationships.

Bloodstain Pattern Analysis (BPA)

  • Definition:

    • The study and analysis of bloodstains at a known or suspected crime scene, aimed at drawing conclusions about the nature, timing, and circumstances of the crime.

  • Necessary Training:

    • Becoming a Bloodstain Pattern Analyst requires specialized training and mentorship.

Insights from Bloodstain Evidence

  • Bloodstains offer vital information such as:

    • The direction of origin of blood.

    • The impact angle at which blood struck a surface.

    • The positioning of victims during an injury event.

    • The movement of a bleeding individual at the crime scene.

    • Estimation of the number of blows that caused bloodshed.

Directions and Angles of Impact

  • Shape and Orientation of Bloodstains:

    • The pointed end of an elliptical bloodstain indicates the direction of travel.

    • Impact angle is determined based on the degree of circular distortion in the stain.

  • Mathematical Expression for Impact Angle:

    • ext{Sin A} = rac{ ext{width of bloodstain}}{ ext{length of bloodstain}}

Types of Impact Spatter

  • Blood spatter occurs from objects impacting a source of blood:

    • Forward Spatter: Blood that travels away from the source in line with the force.

    • Back Spatter: Blood projected backward from the source.

  • Spatter Types:

    • Low Velocity Spatter: Generated at 5 ft/s or lower, with drops larger than 4 mm.

    • Medium Velocity Spatter: Between 5-25 ft/s, with drops in size 1-4 mm.

    • High Velocity Spatter: Over 100 ft/s, with drops smaller than 1 mm and often associated with gunshot wounds.

Bloodstain Spatter Patterns

  • Key Patterns include:

    • Gunshot Spatter: Caused by blowback from close gunshots.

    • Cast Off: Resulting from blood being flung from a moving object.

    • Arterial Spray: From arterial injuries, often producing spurts.

    • Void Patterns: Areas where blood did not deposit due to obstruction by objects.

    • Transfer Patterns: Created when objects with blood touch non-bloodied surfaces.

  • Documentation of Blood Patterns:

    • Employ notes, sketches, and photos of the crime scene.

    • Utilize grid methods for pattern analysis.

  • Photography Tools:

    • Use of sticky scales for precise measurements during documentation of bloodstains.

Blood Enhancement Chemicals

  • Luminol:

    • Reacts with iron in hemoglobin to emit blue light when applied to suspected bloodstains, highly sensitive, and must be performed in darkness.

  • Leuco-Crystal Violet:

    • Enhances visibility of existing bloodstains, effective for contrast purposes.

Tire Track Evidence Collection

  • Tire Track Impressions:

    • Similar to footwear; consist of both 2D and 3D impressions.

    • Scale alignment is critical for accurate collection.

  • Techniques for Tire Track Collection:

    • Photography and casting to superbly document evidence.

  • Descriptions for Tire Tracks:

    • Require details of location, direction, substrate, preservation techniques, and comparative analysis.

Databases for Footwear and Tire Tracks

  • SICAR Database:

    • Maintained by RCMP for footwear images.

  • Tire Track Database:

    • Maintained by the RCMP, developed by Corporal Jim Giczi.

    • Contains approximately 1,100 tire types linked to crime scene investigations, such as the Lloyd homicide case.