FSC100~ EXAM (Readings)

Chapter 4: Fingerprints and Palmprints

Key Terms:

- Latent Prints: Invisible prints left by oils or sweat, made visible through powder, chemicals, or light.

- Patent Prints: Visible prints, often left in substances like blood, paint, or ink.

- Plastic Prints: Impressions in soft materials like clay, wax, or tar.

- Ridge Characteristics (Minutiae):

- Ending Ridge: Where a ridge ends abruptly.

- Bifurcation: A ridge splitting into two.

- Dot/Island: A very short ridge, appearing as a dot.

- Lake: A ridge that forms an enclosed space.

- Hook/Spur: A short ridge off the main ridge.

- Crossover: The intersection of two ridges.

- Bridge: A small ridge connecting two parallel ridges.

Class Characteristics:

- Fingerprint patterns: Arches, Loops, and Whorls.

- Ridge counts and pattern types are general class characteristics.

Collection:

1. Detection:

- Use oblique lighting or lasers for locating latent prints.

- Powders (e.g., black, white, magnetic) for non-porous surfaces.

- Chemicals like ninhydrin (reacts with amino acids) or cyanoacrylate fuming for porous surfaces.

2. Photography:

- Always photograph prints in their original condition.

- Use macro lenses and scales.

3. Preservation:

- Lift prints using adhesive tape for smooth surfaces.

- Store developed prints on backing cards labeled with case details.

Identification:

- Compare minutiae (10–16 points of comparison are standard in some jurisdictions).

- Utilize databases like IAFIS and AFIS.

Documentation:

- Record the location, orientation, and condition of the print.

- Include sketches showing the context of print placement.

Chapter 5: Trace and Impression Evidence

Key Terms:

- Trace Evidence: Small materials like hair, fibers, glass, and paint that can transfer between individuals or locations.

- Impression Evidence: Imprints like shoeprints, tire tracks, and toolmarks.

- Class Characteristics:

- Fibers: Type (natural or synthetic), color, weave pattern.

- Hair: Species, length, color, and cuticle pattern.

- Glass: Thickness, refractive index, fracture patterns.

- Shoeprints: Tread pattern, brand, and size.

Collection:

1. Trace Evidence:

- Use tweezers, lint rollers, or vacuum devices.

- Collect fibers directly onto tape or place them in paper folds.

2. Impression Evidence:

- Photograph impressions at 90° with scales.

- Cast impressions using dental stone for footprints or tire marks.

Preservation:

- Store fibers or hairs in sealed envelopes.

- Protect glass fragments with rigid containers.

Identification:

- Microscope analysis for fibers and hairs.

- Comparison of toolmarks or impressions using overlay techniques.

Documentation:

- Record measurements of impressions.

- Document locations with sketches and wide-angle photos.

Chapter 6: Body Fluid Evidence

Key Terms:

- Serology: Study of bodily fluids like blood, semen, and saliva.

- DNA Profiling: Identifying individuals through genetic material.

- Touch DNA: DNA obtained from skin cells left on objects.

Class Characteristics:

- Blood type (A, B, AB, O).

- General enzyme or protein markers.

Collection:

1. Wet Evidence:

- Absorb onto sterile cotton or filter paper.

- Air-dry before packaging in paper envelopes.

2. Dry Evidence:

- Scrape gently with a clean tool.

- Avoid contamination by using gloves and clean instruments.

Preservation:

- Always air-dry evidence before packaging.

- Store in breathable containers to prevent mold growth.

Identification:

- Presumptive Tests:

- Luminol: Reacts with blood hemoglobin.

- Phenolphthalein (Kastle-Meyer Test): Indicates blood presence.

- Confirmatory tests like DNA analysis.

Documentation:

- Photograph stains before collection.

- Record measurements and spatial context.

Chapter 7: Blood Spatter Evidence

Key Terms:

- Impact Spatter: Caused by a force striking a blood source.

- Transfer Patterns: Impressions made by blood-covered objects.

Class Characteristics:

- General directionality of patterns.

- Shape and size of stains.

Collection:

- Document the entire pattern with wide-angle shots.

- Take close-ups of individual stains with scales.

Preservation:

- Swab blood stains for lab analysis.

- Ensure clothing or objects with stains are stored properly.

Identification:

- Angle of Impact: Calculated using trigonometry.

- Point of Convergence: Determines the origin of the blood source.

Documentation:

- Sketch the overall pattern and take overlapping photos.

Chapter 11: Death Investigation

Key Terms:

- Cause of Death: The direct medical reason for death (e.g., gunshot wound).

- Manner of Death: Homicide, suicide, accident, natural causes, or undetermined.

- Postmortem Interval (PMI): The time elapsed since death.

Collection:

- Document the body’s position with wide-angle and close-up photos.

- Collect biological evidence (e.g., hair, blood).

Preservation:

- Store evidence from the body (clothing, swabs) in appropriate containers.

Identification:

- Use autopsy findings, toxicology reports, and photographic evidence.

Documentation:

- Photograph the entire body and surroundings before any movement.

Chapter 13: Firearms and Toolmarks

Key Terms:

- Ballistics: Study of projectiles, firearms, and ammunition.

- Toolmarks: Impressions left by tools on surfaces.

Class Characteristics:

- Gun type, caliber, rifling pattern.

Collection:

- Photograph firearms in situ.

- Use clean gloves to handle evidence to prevent contamination.

Preservation:

- Keep bullets or casings in separate labeled containers.

Identification:

- Match striations on bullets to a firearm.

Documentation:

- Include measurements and photographs of all collected items.

Chapter 15: Arson and Explosives

Key Terms:

- Accelerants: Substances like gasoline used to start fires.

- Blast Marks: Patterns left by explosions.

Collection:

- Collect debris samples from areas with suspected accelerants.

- Photograph fire patterns and blast areas.

Preservation:

- Store debris in airtight containers for chemical analysis.

Identification:

- Test for chemical residues in a lab.

Documentation:

- Photograph all burn patterns and debris.

Photography

General Guidelines for Crime Scene Photography

1. Camera Equipment:

- Use a digital single-lens reflex (DSLR) camera for high-resolution images.

- Equip the camera with macro lenses for detailed close-ups and wide-angle lenses for overall scene documentation.

- Always use a tripod for steady shots, particularly in low light.

- Utilize an external flash or additional lighting sources for accurate illumination.

2. Photographic Sequence:

- Overview Photos:

- Capture the scene as a whole, showing its location and orientation.

- Include entry and exit points, landmarks, and any contextual details.

- Midrange Photos:

- Focus on groups of evidence or specific areas of interest to establish their relationship to the scene.

- Close-Up Photos:

- Use macro photography for individual pieces of evidence, ensuring fine details are visible.

- Include scales or rulers in at least one photo for size reference.

3. Lighting Techniques:

- Use oblique lighting (light from an angle) to enhance textures, such as fingerprints or footprints.

- Employ alternate light sources (ALS), like UV or blue light, for detecting biological stains or latent prints.

4. Photographic Logs:

- Maintain a log recording the time, date, photographer, subject of each photo, and camera settings.

- Ensure all photographs are numbered and correlated to the evidence inventory.

Evidence-Specific Photography Techniques

Fingerprints and Palmprints

- Photographing Latent Prints:

- Before using powders or chemicals, take photos under oblique lighting to enhance contrast.

- After development with powder or chemicals, photograph prints again to show enhanced details.

- Use filters or monochrome settings to highlight contrast for clear minutiae (e.g., ridges and bifurcations).

- Angles:

- Always photograph from 90° above the print to avoid distortion.

- Take additional angled shots to capture surface curvature, if prints are on irregular objects.

Trace Evidence

- Hair, Fibers, and Glass:

- Use macro lenses for extreme close-ups of fibers or hairs in situ.

- Place a dark or light contrasting background under the evidence for clarity.

- Use lighting to emphasize texture, color, and weave patterns.

- Shoeprints and Tire Tracks:

- Position the camera directly above the impression at 90°.

- Include a measurement scale parallel to the edges of the print.

- If the print is faint, apply oblique lighting to highlight surface variations.

Blood and Biological Evidence

- Blood Spatter Patterns:

- Start with overview shots of the entire pattern to document spatial relationships.

- Take close-ups of individual stains with scales placed parallel to the surface.

- Capture droplets from multiple angles to calculate directionality and point of convergence.

- Stains on Vertical Surfaces:

- Position the camera directly facing the stain to prevent distortion.

- Use a tripod and remote shutter release to avoid camera shake.

- Luminol or Fluorescence:

- Use a tripod for stability in low-light conditions.

- Adjust the camera’s exposure settings to capture the glow from luminol reactions.

Firearms and Toolmarks

- Firearms:

- Photograph the weapon in situ before moving it, showing its exact position and orientation.

- Take close-ups of serial numbers, scratches, and marks.

- Toolmarks:

- Use oblique lighting to highlight grooves and indentations.

- Photograph toolmarks from multiple angles to provide a 3D perspective.

Death Investigations

- Body Documentation:

- Start with wide-angle shots showing the entire body and its surroundings.

- Progress to midrange shots focusing on wounds, clothing, and body position.

- For injuries, use close-ups with scales and adjust lighting to reveal details of abrasions or lacerations.

- Post-Movement Photography:

- After the body is moved, photograph the area underneath to document any hidden evidence.

Arson and Explosives

- Burn Patterns:

- Capture wide shots of entire structures or rooms to document burn patterns and areas of origin.

- Take midrange and close-ups of specific damage areas, such as charred debris or explosive blast marks.

- Debris Samples:

- Photograph each collection point before and after debris is removed.

- Use scales to indicate the size of burn patterns or explosive residue.

Key Notes on Documentation

- Scales:

- Always include a forensic scale or ruler in at least one close-up image.

- Ensure scales are level with the evidence to maintain accurate size representation.

- Angles and Perspective:

- Avoid angled or distorted shots unless necessary for documenting irregular surfaces.

- Include compass direction markers in overview photos to establish orientation.

- Metadata:

- Save all images with embedded metadata, including timestamps and camera settings, to preserve chain-of-custody integrity.

Paper Evidence

Key Concepts and Class Characteristics

1. Class Characteristics:

- Type of Paper: Weight, texture, size, and color (e.g., printer paper, cardstock, notebook paper).

- Ink Characteristics: Ink type (ballpoint, gel, fountain), color, and consistency.

- Watermarks: Design or patterns embedded in the paper during manufacturing.

- Printing Features: Fonts, alignments, or misalignments, and typeface defects.

2. Individual Characteristics:

- Handwriting (loops, angles, pressure marks).

- Unique tears, stains, or folds.

Collection Methods

1. Approach to Paper Evidence:

- Paper evidence is highly sensitive to contamination, folds, or tears.

- Use gloved hands or tweezers to handle documents.

- If paper is found wet, let it air-dry in a controlled environment before packaging to prevent mold.

2. Photographic Documentation:

- Before collecting, photograph documents in situ to capture their spatial relationship to the scene.

- Use flat lighting for clear imaging.

- Employ macro photography for close-ups of fine details, such as handwriting or ink.

3. Context:

- If found torn, ensure all pieces are collected for potential reconstruction.

- Note nearby evidence (e.g., pens, envelopes, or stamps) that might connect to the paper.

Preservation of Paper Evidence

1. Packaging:

- Place paper items in protective sleeves or acid-free paper envelopes to prevent further degradation.

- Avoid using plastic containers for long-term storage to reduce condensation or chemical interaction.

2. Avoidance of Damage:

- Do not fold, bend, or staple paper evidence.

- For fragile documents, consider placing them between rigid supports (e.g., cardboard) for transport.

3. Environmental Control:

- Store paper in a dry, temperature-controlled environment to prevent deterioration or ink fading.

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Identification Techniques

1. Analysis:

- Examine watermarks under a light source to determine manufacturing details.

- Conduct UV or infrared light analysis to reveal hidden writing or erased marks.

- Use chemical analysis to determine ink composition, often matching it to a specific pen or batch.

2. Handwriting Analysis:

- Identify individual characteristics like stroke consistency, spacing, and slant.

- Compare questioned documents with known exemplars (samples of the individual’s handwriting).

3. Other Techniques:

- Match torn edges to recovered pieces.

- Analyze printer or typewriter marks using forensic printing identification techniques.

Documentation

1. Photographic Documentation:

- Capture images from multiple angles to account for glare or texture differences.

- Include a scale in all photos to indicate the size of the document.

2. Sketches and Notes:

- Record the location, orientation, and condition of the paper at the scene.

- Note any visible markings, stains, or unusual features (e.g., singed edges in fire cases).

3. Chain of Custody:

- Label all paper evidence with case details, including date, location, and time of collection.

- Maintain a secure chain of custody, as paper evidence is easily altered or lost.

Case Example Applications

- Forgery Cases: Ink composition, handwriting characteristics, and paper type may identify alterations or forgeries.

- Anonymous Letters: Analysis of handwriting, ink, and typeface can lead to the identification of the sender.

- Burned Paper Evidence: Partially burned documents can sometimes be recovered using forensic reconstruction techniques and photographed under high-contrast lighting.