Forensic Serology: Analyzing Bodily Fluids

• Forensic serology involves the examination and analysis of bodily fluids found at a crime scene.
• Crucial part of forensic science, aiding in crime scene reconstruction and identification of individuals involved.

Types of Biological Evidence in Forensic Serology

• Blood is analyzed for blood type, DNA, and presence of drugs or alcohol.
• Semen is examined for the presence of sperm and DNA, and is crucial in sexual assault cases.
• Saliva can be a source of DNA and indicates the presence of the person at a location.
• Urine may contain DNA and can be tested for drugs or other substances.
• Other bodily fluids like sweat, tears, and fecal matter can also be analyzed, though less common.

Bloodstain Pattern Analysis (BPA)

• BPA is the interpretation of bloodstains to determine the events that caused the bloodshed.
• Helps reconstruct the crime scene by understanding the direction, angle, and velocity of impact.
• Passive stains result from gravity, such as drops, flows, and pools.
• Projected stains occur when blood is propelled by a force, including arterial spurts, cast-off stains from weapons, and impact spatter.
• Transfer stains result from contact between a blood-bearing surface and another surface.

Preliminary Tests for Blood

• Indicate the possible presence of blood, even if it's not visible.
• Highly sensitive but not specific.
• Phenolphthalein test (Kastle-Meyer test) reacts with the heme in hemoglobin to produce a pink color.
• Luminol test reacts with blood to produce luminescence (glow), useful in darkened areas.
• Followed by confirmatory tests to ensure accuracy.

Confirmatory Tests for Blood

• Confirm that the substance is indeed blood
• Determines if it is human or animal blood.
• Microscopic examination aids in the Identification of blood cells
• Immunological tests use antibodies to detect human hemoglobin.

Semen Identification

• Microscopic examination facilitates the identification of spermatozoa.
• Acid phosphatase test identifies acid phosphatase, an enzyme found in high concentrations in seminal fluid.
• Prostate-Specific Antigen (PSA) test identifies PSA, also known as p30, which is a protein produced by the prostate gland and is a specific marker for semen.

Saliva Identification

• Microscopic examination aids in the identification of epithelial cells.
• Amylase test is for the detection of amylase, an enzyme found in high concentrations in saliva.

DNA Analysis in Serology

• DNA analysis has revolutionized forensic serology, allowing for highly specific identification.
• DNA can be extracted from almost any type of biological evidence.
• STR (Short Tandem Repeat) analysis is a common method used to create a DNA profile.
• Mitochondrial DNA (mtDNA) analysis is used when nuclear DNA is degraded or limited, as mtDNA is more abundant.

Crime Scene Analysis: Overview

• Crime scene analysis involves the systematic examination and documentation of a crime scene to gather evidence and reconstruct the events.
• Preserving the crime scene is crucial to prevent contamination or alteration of evidence.
• Documentation includes detailed notes, photographs, and sketches of the scene and evidence.

Steps in Crime Scene Analysis

• Secure and Isolate the Scene by limiting access to authorized personnel to prevent contamination.
• Document the Scene by photographing the scene from multiple angles, including overviews, mid-range, and close-ups with scales and Create sketches or diagrams of the scene, noting the location of evidence.
• Search for Evidence by conducting a systematic search of the scene using various search patterns (e.g., grid, spiral, line, zone).
• Collect and Package Evidence carefully, ensuring proper preservation and chain of custody. Each item should be placed in a separate container, labeled with relevant information (date, time, location, description).
• Maintain Chain of Custody by keeping a meticulous record of who handled the evidence, from collection to analysis, to ensure its integrity in court.

Crime Scene Documentation Techniques

• Photography is essential for capturing the overall scene and specific evidence and should be taken before any evidence is moved.
• Sketching provides a visual representation of the scene, showing the spatial relationships between items, and can be freehand or computer-generated.
• Note-taking involves a detailed written record of observations, actions taken, and evidence collected, while notes should be contemporaneous and accurate.
• Video Recording can provide a dynamic view of the scene, capturing details that might be missed in photographs or sketches.

Search Patterns

• Grid Search: The scene is searched in a grid pattern, ensuring thorough coverage.
• Spiral Search: Start at the center and move outward in a spiral, or vice versa.
• Line Search: Used in large, outdoor scenes; searchers walk in a straight line.
• Zone Search: Divide the scene into zones and assign a searcher to each zone.

Evidence Collection and Preservation

• Biological Evidence is collected using sterile swabs or cutting out the stained area, and must be air-dried before packaging to prevent degradation, and should be stored in paper bags or boxes to allow for ventilation.
• Trace Evidence like small items like hairs, fibers, or glass fragments are collected using tweezers, tape lifts, or vacuuming and packaged in small, clean containers like envelopes or vials.
• Firearms should be handled carefully to preserve fingerprints and DNA. Document the firearm's condition and serial number, and packaged in a secure container.
• Documents should be handled with gloves to avoid adding fingerprints and stored in protective sleeves or folders.

Crime Scene Reconstruction

• Crime scene reconstruction involves forming a hypothesis about the sequence of events based on the evidence collected.
• Bloodstain pattern analysis, trajectory analysis, and other forensic techniques are used to reconstruct the crime.
• It helps investigators understand what happened, identify potential suspects, and corroborate or disprove witness statements.