Introduction to Forensic Science and Medicine Comprehensive Study Guide

Course Information and Objectives

• Instructor: S. O. Keshinro, FMCPath OOU.
• Course Code: FRS $102$.
• Date: May $2026$.
• Primary Learning Objectives:     * Define forensic science, its central objectives, and its foundational principles.     * Discuss common disciplines within forensic science and their roles in criminal investigations.     * Understand forensic medicine and its various aspects in investigations.     * Discuss the roles of pathologists and other medical specialists in Medicolegal Death Investigation (MLDI).     * Analyze legal aspects related to forensic science and medical/pathology practice.     * Participate in case discussions and the application of forensic methods.

Definition and Etymology of Forensic Science

• Etymology: The word "forensic" is derived from the Latin word "forensis," which translates to "before the forum" or "in front of public discussion." In modern contexts, it is synonymous with the terms LEGAL, LAW, and COURT.
• Formal Definition: Forensic science is the application of scientific methods for the purpose of resolving various criminal and sometimes civil legal cases.
• Interdisciplinary Nature: Modern forensic science integrates pure and applied sciences including:     * Biology     * Chemistry     * Physics     * Anatomy     * Digital Science     * Engineering     * Medicine
• Objective: To assist the judiciary in forming an expert opinion to facilitate the conviction of a perpetrator or the exoneration of a defendant, accused person, or litigant.

Aims and Systematic Methodology

• Primary Aim: To establish connections or links between persons (suspects) and the crime (including the scene, physical evidence, and victims).
• Reproducibility: As a science, forensic methods must be reproducible. This is achieved through a systematic approach to:     * Recognize/Identify evidence.     * Collect evidence.     * Preserve evidence.     * Analyze evidence recovered from a crime scene.
• Bridge to the Courtroom: Forensic science serves to bridge the informational gap between a crime scene and the legal proceedings.
• Chain of Custody (CoC): This is a formal record that outlines the handling and processing of evidence in legal and investigative contexts. It is essential for preserving the legal integrity of the evidence.

Methods of Crime Resolution

• Testimonials:     * Confessions: Provided by a suspect. While highly valuable, they are often unreliable and subject to legal hurdles regarding police procedure and admissibility. Under the Administration of Criminal Justice Act (ACJA) $2015$, confessions must be recorded.     * Statements: Provided by victims or witnesses. These are highly subjective and influenced by the observer's perspective and the physical conditions of the scene.
• Physical/Real/Material Evidence:     * Typically comprises inanimate objects, ranging from microscopic trace evidence to large, immovable materials.     * Requires impartial and verifiable scientific methods for analysis, supported by proper Chain of Custody documentation.

The Locard’s Exchange Principle

• The Principle: Established by Dr. Edmond Locard ($1877$ – $1966$) in $1920$. It states: "Whenever two objects come into contact, a mutual exchange of matter will take place between them."
• Core Maxim: "Every contact leaves a trace."
• Significance: This principle is the basis for the transfer and recovery of evidence (e.g., fibers, fingerprints, DNA, soil, gunshot residue) between the suspect, victim, and environment.
• Historical Note: Dr. Locard established the first crime laboratory within the Lyon Police Department in France.

Detailed Timeline of Forensic Science Development

• A.D. $700s$: Fingerprints first used by the Chinese for document individualization.
• $1248$: "Hsi Duan Yu" (The Washing Away of Wrongs), a Chinese book, discusses using medical knowledge for crime solving.
• $1686$: Marcello Malpighi notes fingerprint characteristics but does not link them to individual identification.
• $1784$: John Toms is sentenced in Lancaster, England, after a torn newspaper piece found on him matched a piece in a pistol—the first recorded case of physical document matching.
• $1800s$: Thomas Bewick uses fingerprints to identify his published books.
• $1810$: Eugne Franois Vidocq establishes the Sret of Paris, the first detective force.
• $1813$: Mathiew Orfila (Father of Modern Toxicology) publishes "Traite des Poisons" and contributes to forensic blood testing.
• $1823$: John Evangelist Purkinji classifies fingerprints into $9$ major types.
• $1831$: Leuchs notices amylase activity in human saliva.
• $1835$: Henry Goddard performs the first bullet comparison.
• $1836$: James Marsh first detects arsenic in toxicology for a criminal trial.
• $1838$: William Stewart Baltimore murders in the US are solved via forensic firearms examination.
• $1839$: H. Bayard publishes the first reliable method for microscopic sperm detection.
• $1851$: Jean Servais Stas identifies poison in body tissues.
• $1853$: Ludwig Teichmann develops the first microscopic crystal test for hemoglobin using hemin crystals.
• $1856$: Sir William Herschel uses thumb impressions for document verification in place of signatures.
• $1858$: William Herschel uses palm prints to sign a road contract in Bengal.
• $1862$: J. (Izaak) Van Deen develops a preliminary blood test using guinea pigs.
• $1877$: Thomas Taylor recommends palm and finger markings for identification in criminal cases.
• $1879$: Rudolph Virchow identifies the limitations of hair analysis.
• $1883$: Alphonse Bertillon uses anthropometry to identify a recidivist.
• $1889$: Alexandre Lacassagne attempts to link bullets to gun barrels using lands and grooves.
• $1892$: Francis Galton publishes "Fingerprints."
• $1900$: Karl Landsteiner develops human blood groups (Nobel Prize in $1930$).
• $1901$: Edward Richard Henry (Scotland Yard) implements fingerprints over the Bertillon system.
• $1902$: Forensic photography becomes central to European forensic education hubs.
• $1903$: Fingerprints used for offender identification at New York State Prison/Leavenworth after the Bertillon system fails in the Will West case.
• $1905$: FBI established by President Theodore Roosevelt.
• $1910$: Edmond Locard establishes the first police crime lab; Albert S. Osborne publishes "Questioned Documents."
• $1912$: Masaeo Takayama develops a microscopic crystal test for hemoglobin using hemochromogen crystals.
• $1915$: Leone Lattes develops the first antibody test for ABO blood groups.
• $1916$: Albert Schneider uses a vacuum apparatus for trace evidence collection.
• $1918$: Locard recommends $12$ matching points for fingerprint identification.
• $1920$: Calvin Goddard (with Gravelle, Waite, and Fisher) uses a comparison microscope for bullets.
• $1921$: John Larson and Leonard Keeler design the portable polygraph.
• $1923$: Vittorio Siracusa develops the Absorption-elution test for ABO blood typing of stains.
• $1924$: August Vollmer establishes the first US police crime lab.
• $1925$: Saburo Sirai recognizes secretion of group-specific antigens into body fluids.
• $1931$: Franz Josef Holzer develops absorption-inhibition ABO typing; Lucas applies gas chromatography (GC) to petroleum products.
• $1937$: Walter Specht develops luminol for blood tests.
• $1941$: Voiceprint identification introduced by Murray Hill (Bell Labs) and L. G. Kersta.
• $1945$: Frank Lundquist develops the acid phosphatase test for semen.
• $1946$: Mourant discusses the Lewis blood group.
• $1950$: Max Frei-Sulzer develops the tape-lift method for trace evidence.
• $1951$: M. Cutbush discusses the Duffy blood group system.
• $1953$: Kirk publishes "Crime Investigation."
• $1954$: R. F. Borkenstein discovers the breathalyzer.
• $1966$: Culliford and Wraxall develop immunoelectrophoresis for haptoglobin typing.
• $1967$: Culliford introduces gel-based methods for isoenzymes in bloodstains.
• $1974$: SEM-EDX (Scanning Electron Microscopy-Energy Dispersive X-rays) developed for gunshot residue detection by Wessel et al.
• $1976$: Zoro and Hadley evaluate GC-MS for forensic use.
• $1977$: Soba develops prints via "Superglue" fuming; FBI introduces AFIS.
• $1984$: Jeffreys develops DNA profiling.
• $1991$: Walsh Automation Inc. launches IBIS for bullet/casing comparison.
• $1996$: Mitochondrial DNA typing accepted in US court (Tennessee v. Ware).
• $1999$: FBI and ATF form the National Integrated Ballistics Identification Network.

Fingerprint Analysis and Dactyloscopy

• Dactyloscopy/Dermatoglyphics: The study of skin markings on fingers, hands, and feet.
• Uniqueness: Fingerprints are unique to every individual (even identical twins) and vary between a single individual’s fingers.
• Latent Fingerprints: Invisible impressions left by natural oils and sweat.
• AFIS (Automated Fingerprint Identification System): Technology that converts fingerprints into digital formats to match against databases of known and unknown prints.
• Anatomical features identified in prints:     * Core, Crossover, Bifurcation, Ridge ending, Island, Delta, and Pore.

Forensic DNA Analysis

• Genetic Fingerprinting: Analysis of molecules in the nucleus/chromosome or mitochondrion.
• Mechanism: Genetic information is carried in the order of nucleotide arrangements, specifically Short Tandem Repeats (STRs).
• The Process: Extraction → Quantification → Genotyping → Matching/Interpretation.
• CODIS (Combined DNA Index System): Managed by the FBI, using $13$ STRs and amelogenin for sex determination.

Forensic Serology and Bloodstain Pattern Analysis (BSPA)

• Serum: Clear, yellowish fluid from blood, lacking cellular components and clotting proteins (plasma minus clotting factors).
• Forensic Serology: Analysis of blood and biological fluids (Saliva, Semen, Vaginal fluid, Urine, Sweat) for legal purposes via antigen-antibody reactions.
• BSPA: Reconstruction of bloodshed events using biological, physical, and mathematical principles to interpret stain size, shape, and distribution.
• Blood Groups:     * Group A: A antigen, Anti-B antibodies.     * Group B: B antigen, Anti-A antibodies.     * Group AB: A and B antigens, No antibodies.     * Group O: No antigens, Anti-A and Anti-B antibodies.

Questioned Document Examination (QDE)

• Purpose: To establish document genuineness, identify or eliminate handwriting sources, and identifying mechanical origins (typewriting/marks).
• Materials Analyzed: Bank checks, currency, stamps, indented impressions, and variously produced texts.

Digital Forensics

• Definition: Identification, preservation, analysis, and presentation of digital evidence from electronic devices.
• Sources: Computers, mobile phones, cloud storage, CCTV, USB drives, network logs, social media, and e-watches.

Forensic Toxicology and Chemistry

• Scope: Identifying drugs, alcohol, or poisons affecting physiology.
• Application: Death investigation, drug abuse in sports, DUI (Driving Under the Influence), motor vehicle accidents (MVA), and air disasters.
• Materials: Blood, bodily fluids, tissues, and organs.
• Tools: Spectrophotometer, Mass Spectrometer (MS), Gas Chromatography (GC).
• Forensic Chemistry: Analysis of manufactured/natural products like explosives and gunshot residue.

Ballistics

• Classification:     * Internal: Propulsion within the weapon.     * External: Flight of the projectile.     * Terminal: Effects upon impact.
• Forensic Questions: Is it a firearm? Is it functional? Was it fired recently? Was there an accidental discharge? Do scene bullets match the weapon?

Forensic Anthropology and Psychology

• Anthropology: Analysis of human skeletal remains (osteology) to determine sex, ancestry, and age. Used for badly decomposed or skeletonized remains.
• Psychology: Application of psychological theories to the legal system.     * Areas: Criminal Profiling, Competency Evaluations, Insanity Pleas, Eyewitness Reliability, Risk Assessment (recidivism), and Victim Support.

Forensic Medicine and Pathology

• Forensic Medicine Components:     * Medical Jurisprudence: Regulations guiding practice (e.g., MDCN, ethics, human rights).     * Clinical Forensic Medicine: Examining the living (sexual assault/SGBV, industrial disease, paternity, patients in custody).     * Forensic Pathology: Medicolegal Death Investigation (MLDI).
• Autopsy (Postmortem Examination): Derived from "autopsia" (to see for oneself).     * Aims: Determine cause/manner of death, vital statistics, medical audit (e.g., COVID-$19$), insurance purposes, Human Identification (DVI), and family closure.     * Training for Pathologists: Medical School ($6$ years) → House Job ($1$ year) → NYSC ($1$ year) → Residency ($6$ years).

Legal Framework in Nigeria

• Administration of Criminal Justice Act (ACJA) $2015$:     * Section $15$: Mandatory electronic/video recording of confessions.     * Section $10$: Mandatory inventory of seized property (Chain of Custody).     * Section $6(2)$: Police may request medical exams of suspects.
• Coroners Law:     * Investigates sudden, violent, or unexplained deaths.     * Sections $14$–$15$: Legal authority for evidence collection.     * Section $25$: Validates forensic practitioners as expert witnesses.

Humanitarian Forensics

• Focus: Developed by the ICRC for victims of armed conflicts and catastrophes.
• Aim: Dignified management of the dead, recovering and identifying remains for humanitarian rather than criminal purposes.