FRS 102: Crime Scene Investigation and Introductory Forensic Science

Comprehensive practice flashcards reviewing crime scene investigation procedures, historical milestones, legal-medical aspects, and analytical techniques covered in FRS 102.

What is Locard's Exchange Principle, and who formulated it?

Formulated by Dr. Edmond Locard ($1877-1966$), a French criminologist known as the Sherlock Holmes of France, it states that 'every contact leaves a trace.' A perpetrator will always bring something into a crime scene and leave with something.

What is the primary difference between a primary crime scene and a secondary crime scene?

A primary crime scene is the location where the crime actually took place or was committed (only $1$ primary crime scene exists per case). A secondary crime scene is a location outside the original scene connected to the crime where criminal activity or evidence exists, and numerous secondary crime scenes may exist.

How must biological evidence such as blood or semen be properly packaged at a crime scene?

Biological evidence must be air-dried before packaging and placed in a paper package to remove moisture build-up and prevent contamination from bacterial growth.

What is the distinction between a rough sketch and a finished sketch in crime scene diagramming?

A rough sketch is drawn by a police officer and is not drawn to scale, but portrays accurate distances and dimensions. A finished sketch is a completed diagram drawn to scale.

What is the chain of custody in forensic investigation, and who are the key individuals involved?

Chain of custody is a legal term referring to the order and manner in which physical or electronic evidence is handled from initial collection. Key people involved include police, media, medical lab experts, and the jury.

What is the etymological origin and historical meaning of the word 'forensic'?

The word 'forensic' originates from the Roman Latin word 'forem', meaning 'of or before the forum,' referring to presenting and deliberating criminal charges publicly before a forum in ancient Rome.

What landmark text was written by Song Ci in $1248\,\text{AD}$, and what was its scientific significance?

Song Ci wrote 'Xi Yuan Lu' ('Washing Away of Wrongs') in China in $1248\,\text{AD}$, marking the first written application of medicine and entomology to criminal investigations.

What early contributions to forensic toxicology were made by Carl Wilhelm Scheele and Mathieu Orfila?

Carl Wilhelm Scheele first discovered how to detect arsenic in $1773$. In $1813$, Mathieu Orfila published foundational work on detecting poisons, earning him the title of the father of forensic toxicology.

What milestone in physical matchmaking occurred in England in $1784$?

John Toms was convicted in England using a torn piece of newspaper found in his pocket that physically matched a paper wad found in a pistol.

Who developed the identification system known as anthropometry in $1879$, and how did it function?

Alphonse Bertillon developed anthropometry in $1879$, which used a system of precise body measurements to identify repeat criminals.

What key forensic developments took place in $1892$ and $1901$ regarding fingerprints and blood?

In $1892$, Sir Francis Galton and Juan Vucetich established fingerprint uniqueness and classification systems. In $1901$, Karl Landsteiner discovered human blood groups, and Paul Uhlenhuth created a test to distinguish human blood from animal blood.

What major forensic innovations were introduced by Calvin Goddard and Sir Alec Jeffreys?

Calvin Goddard improved firearm comparison in the $1920\text{s}$ using the comparison microscope, and Sir Alec Jeffreys invented DNA fingerprinting/profiling in $1984$.

In electrochemical analysis, how do potentiometry and voltammetry differ?

Potentiometry measures the potential (voltage) of an electrochemical cell under zero current flow to determine analyte concentration, whereas voltammetry measures electric current in a cell as a function of applied potential.

What are the forensic applications of Gas Chromatography (GC), High-Performance Liquid Chromatography (HPLC), and Thin-Layer Chromatography (TLC)?

GC separates volatile organic compounds (often paired with mass spectrometry for drug and accelerant tests), HPLC analyzes non-volatile or thermally fragile chemical/pharmaceutical compounds, and TLC provides quick visual separation for preliminary ink, poison, or illicit drug screenings.

How are Capillary Electrophoresis and Scanning Electron Microscopy (SEM/SEM-EDS) applied in forensic analysis?

Capillary Electrophoresis uses electricity to sort charged DNA pieces by size for genetic profiling. SEM/SEM-EDS magnifies microscopic trace items and checks elemental composition, heavily used to analyze gunshot residue.

In mathematical analysis, how do analytical methods differ from numerical methods?

Analytical methods rely on exact mathematical equations and closed-form solutions to solve simplified, often $1\text{-dimensional}$ problems. Numerical methods rely on approximation algorithms when mathematical models are too complex to solve exactly.

What are the four primary categories of analytical techniques covered in forensic science?

1. Chemical and Scientific Analysis; 2. Data and Business Analysis; 3. Qualitative and Conceptual Techniques; 4. Mathematical and Computational Analysis Techniques.

What is the primary role of an expert witness testimony in court proceedings?

To provide an impartial, mandated scientific explanation of complex technical data as a neutral officer of the court, rather than acting as an advocate for the prosecution or defense.

What immediate procedures must an investigator take upon arrival at a crime scene?

Record the time, date, and weather conditions; secure and preserve the area; call medical assistance if a victim is battling to survive; restrict scene movements; protect open-space evidence from rain, sun, or fire; take eye witnesses to a safe place; and record all movements into the scene and items touched.

What are the key medical disciplines within forensic science and their main roles?

Forensic Pathology (autopsies to find cause/manner/time of death), Clinical Forensic Medicine (interprets trauma on living victims), Forensic Toxicology (detects drugs/poisons in tissues/fluids), Forensic Anthropology and Odontology (analyzes skeletal remains and dental records), and Forensic Psychiatry/Psychology (evaluates mental state and competence).