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Pre-requisite

Course description

Forensics offers a unique framework for a combination of principles from biology; chemistry; and physics; as well as an understanding of how scientific principles are handled within the legal system. The course will develop an understanding of various types of forensic evidence and their analysis within a laboratory setting; combined with real-life case studies and an emphasis on team collaboration; similar to how Crime Scene Investigation Teams analyze case evidence to draw a conclusion. The course is designed for students with an interest in Forensics; Law Enforcement; Chemistry; and those wishing to pursue a legal career.
The objectives of this course include understanding how scientific principles are used in analysis of crime scene evidence; and how a criminal investigation requires a broad understanding of biology; chemistry and physics. Students will understand how evidence is collected and analyzed; and apply the principles of the scientific method to various case studies and laboratory experiences involving analysis of crime scene evidence. Major concepts in biology; chemistry and physics will be covered; with an emphasis on conceptual understanding combined with the ability to connect evidence to a claim.
LABORATORY EXPERIENCE: Students are expected to maintain a bound composition lab notebook divided into sections for each major class of evidence. The lab notebook will contain important information and reference exemplars for each class of evidence; consisting of drawings; photographs; and physical samples (when appropriate).
MAJOR TOPICS:
I. EVIDENCE COLLECTION
- Eyewitness Testimony
- Qualitative & Quantitative Observation
- Chain of Custody
- Locard's Principle
- Crime Scene Documentation
- Evidence Collection
- Lab Safety Equipment and Procedures
Labs/Activities: Eyewitness Testimony TV Commercial Activity; FACES Software Activity; Chain of Custody Activity; Crime Scene Sketches; Evidence Collection & Labeling Activity; Safety & Equipment Orientation – CSI Tech Level One Exam
II. HAIR AND FIBER EVIDENCE
- Characteristics of Human vs. Animal Hair
- Forensic Analysis of Hair
- Physical and Chemical Properties of Textiles
Labs/Activities: Structure of Hair Lab; Human vs. Animal Lab; Hair Testimony Essay; Carpet Fiber Lab; Physical and Chemical Properties of Hair Lab – CSI Hair/Fiber Certification Exam
III. FINGERPRINTING
- History of Fingerprints
- Characteristics and Types of Fingerprints
- Latent Print Collection
- Structure of DNA
- Collection of DNA Evidence
- Analysis & Matching of DNA Evidence
Labs/Activities: Describe Your Fingerprint; Latent Fingerprint Collection Lab; Ten Card Activity; Fingerprint Matching Lab; DNA Electrophoresis Gel Lab; Restriction Enzyme Activity; Missing Romanov Activity; Applications of DNA Analysis Activity - CSI Fingerprint Certification Exam; CSI DNA Certification Exam
IV. BLOOD; BLOOD SPATTER AND BALLISTICS
- Composition of Blood and Blood Cell Function
- Blood Types
- Blood Stain Detection
- Blood Spatter Analysis
- Characteristics of Projectile Weapons
- Barrel Rifling and Bullet Matching
- Bullet Recovery
Labs/Activities: Blood Typing Lab; Blood Detection Lab; Blood Spatter Analysis Activity; Firing Pin Match Lab; Bullet Trajectory Lab – CSI Blood Certification Exam; CSI Ballistics Certification Exam
V. TOXICOLOGY & DRUG IDENTIFICATION
- Types of controlled substances
- Signs and symptoms of ingestion/overdose of various drugs
- Drug identification
Labs/Activities: OTC Drug Analysis Lab; Urinalysis Simulation – CSI Toxicologist Certification Exam
VI. QUESTIONED DOCUMENTS
- Handwriting Analysis
- Questioned Documents Analysis (Forgery)
- Currency Anti-counterfeiting Features
Labs/Activities: Handwriting Analysis; Chromatography Lab; Ransom Note Lab; US Currency Lab – CSI QD Certification Exam
VII. DEATH AND EXAMINATION OF HUMAN REMAINS
- Manners of Death
- Changes in Body Composition & Temperature
- Autopsies
- Insect Colonization and Development
- Human Characteristics from Skeletons
Labs/Activities TOD Using Rigor Mortis Activity; Insect Study; TOD Insect Analysis Lab; Age of Skull Activity; Male Vs. Female Bones Activity; Missing Romanovs Activity; Medical Examiner Activity; Cadaver Lab Field Trip – CSI Coroner Assistant Certification Exam
VIII. SOIL & GLASS
- Soil Composition & Chemistry
- Soil Collection & Analysis
- Types and Properties of Glass
- Refractive Index of Glass
- Fracture Patterns
Labs/Activities Soil Profile; Chemical & Physical Analysis of Sand; Glass Fracture Pattern Activity; Glass Density Lab; Refractive Index Activity; Submersion Test Lab – CSI Soil & Glass Certification Exam
IX. COURTROOM TESTIMONY
- Preparation of Reports
- Courtroom Dress and Demeanor
- Testimony and Cross-Examination
FINAL PROJECT - Mock Crime Scene CSI Team Investigation & Mock Trial (Cross-Content project with Street Law) – CSI LEAD INVESTIGATOR Certification Exam
COURSE RESOURCES
Forensic Science: Fundamentals & Investigations – Anthony J. Bertino – Cengage Learning
Crime Scene Investigations (Second Edition) – Adams; Caddell & Krutsinger; Prentice Hall
Top Shelf Forensics – Deslich & Funkhouser; Walch Publishing
Crime Scene Investigation & Reconstruction – Ogle; Pearson Prentice Hall
Basic Laboratory Exercises for Forensic Science – Saferstein; Pearson Prentice Hall
Forensic Science Strategies Workshop Handbook – Bureau of Education & Research (BER)
Investigating Chemistry: A Forensic Science Perspective – Johll; Freeman & Company
SAMPLE FORENSICS LAB
Analysis of Glass as Forensic Evidence
Background/Introduction
Glass fragments can be used to place a suspect at a scene. The fragments may be found in a suspect’s clothing or embedded in shoes as a result of breaking a window; or may be found on a victim of a hit and run; or at a traffic accident scene. If the fragments can be pieced together; like the pieces of a jigsaw puzzle; the evidence can be individualized. More frequently; glass shatters into so many fragments that piecing them together is impossible; so it must be considered class evidence.
Forensic scientists use as many physical properties of glass as possible to characterize the fragments and associate the fragments from the crime scene to a suspect. Also; by studying the fracture patterns of glass; a sequence of events can be deduced to aid in the reconstruction of a crime.
WHAT IS GLASS?
Glass is a common material found in our environment. It is a hard amorphous material; usually transparent; composed primarily of silica (SiO2) and various amounts of oxides. It is brittle and exhibits conchoidal fracture. Glass can be classified into families similar to many other materials previously studies. The families differ widely in chemical composition and physical properties . There is far less variation of properties within the families.
Many of the properties of glass cannot be measured from small fragments and are not of great concern to the forensic scientist. Most important are density and refractive index. Color; thickness; fluorescence and; of course; any extraordinary markings such as striations or dimples may be helpful. Modern instrumentation allows routine determination of trace elements in glass.
Part I – Examination of Glass Pieces
Materials
- glass samples of various sizes
-stereomicroscope
- UV light
- ruler
Safety Precautions – handle glass pieces with care; as they may be sharp. Long-wave UV light sources may cause eye damage over long exposure – do not look directly into the beam of light. Shortwave UV light is extremely hazardous and can cause loss of vision and cataracts.
Procedure
- In your lab notebook; brainstorm with your lab group and list as many possible sources of glass as you can (write neatly). Consider all the materials made of glass and possible uses for glass.
- Examine known samples of glass. Record your observations in your notebook. Place samples on stereomicroscope – draw/record observations in your notebook.
- Use both longwave and shortwave UV lights on each glass sample – note fluorescence and color if appropriate.
Part II – Measuring Density of Glass Fragments
The simplest way to determine density of a glass fragment is called the flotation method. It is based on the observation that a solid particle will float in a medium of greater density; sink in a liquid of lower density; or remain suspended in a liquid of equal density. However; the density of most types of glass is relatively high; requiring a very dense liquid. Another method requires the investigator to calculate density by determining its two components – mass and volume – and calculating the final density. This method will be used in the lab today.
Materials
- sensitive balance
- 10 mL graduated cylinder
- glass samples
Procedure
- measure the mass of each glass sample using the sensitive balance – record to 0.01 grams
- Add 5-6 mL of water to the graduated cylinder – record the exact volume to 0.1 mLs
- Slowly add the glass sample to the cylinder using a pair of tweezers (don’t splash) – record the new volume to 0.1 mLs
- find the difference between the two volumes; then divide the mass by the difference between the two volumes – the density of each glass. Record this value in your notebook.
Part III – Measuring Refractive Index of Glass
Light travels in straight lines until it encounters a material to interact with. When it strikes the surface of a glass object; it can be reflected; absorbed or transmitted. When it passes from one medium into another; it changes direction and speed – this is called refraction. The refractive index is a comparison of the speed of light in a vacuum (the absence of all matter) to the speed of light when traveling through another substance.
If a clear material such as glass is immersed in a liquid with the SAME refractive index; both the glass and the liquid will bend light at the same angle and the glass will seem to disappear.
Materials
- LED flashlight - liquids of various refractive indices
- protractor - forceps/tweezers
- calculator (for sine calculations) - hand lens
- various glass samples - alcohol
- ruler
- sharpie
- white paper
- page protector
- overhead marker
Procedure
- On a piece of white paper; draw a set of axes (x and y) using a ruler and a Sharpie – place inside the page protector.
- Place a glass sample so its edge is along the x axis and it is centered on the y axis – trace the outline of the sample with the overhead marker.
- Place the light source below and to the left of the sample – shine the light so it passes through the sample. Trace the light path from the light source; then through the sample (but not where it comes out the other side).
- Remove the sample. Measure the angle between the path of the light from emitted from the source and the y axis (angle of incidence) – record in notebook. Measure the angle between the path of light through the object and the y axis (angle of refraction). Record in notebook.
- Calculate the refractive index by finding the sine of the angle of incidence and divide by the sine of the angle of refraction – record in notebook.
- Clean off the page protector and repeat with the remaining glass samples.
- Take the glass fragments to the refractive index liquids station. Immerse first sample in first liquid – observe closely with hand lens to determine if the glass seems to “disappear” or is still visible – record in your notebook. Remove the fragment with tweezers; rinse with alcohol and blot dry. Immerse in next liquid – repeat until fragment has been immersed in all liquids. Repeat process with each glass sample.
- Use the table of refractive indices below to determine the refractive index of each piece of glass by matching it with the liquid where it most seemed to “disappear” – record that index in your notebook.
REFRACTIVE INDICES OF SOME LIQUIDS
LIQUID REFRACTIVE INDEX
Methanol 1.329
Water 1.333
Isopropanol 1.377
Olive Oil 1.467
Glycerin 1.473
Castor Oil 1.482
Clove Oil 1.543
Cinnamon Oil 1.619
PART IV – Fracture Patterns
Information about the events of a crime scene can sometimes be constructed by fracture patterns of glass. How the cracks are formed; what shape they have; whether or not the breakage was caused on the inside or outside; are clues to what happened.
Glass is slightly flexible; but when forced to its elastic limit; it will break or fracture. Studying the break or fracture patterns will provide information on the force and direction. When glass is broken with a projectile; such as a bullet or rock; it will form two distinct types of fractures; radial and concentric. When a projectile first hits the glass; the glass will be stretched; causing tension on the back side directly behind the projectile – this causes compression around the point of tension. The radial cracks begin on the opposite side of the force at the point where the projectile hits the glass and radiate outward from the origin of the impact. The concentric cracks begin on the same side as the force; where the tension occurs.
Visible at the edge of the broken glass are stress marks shaped like arches with the perpendicular at the surface where the crack originated. Thus; examination of the edges of a glass fragment that can be fitted into the mosaic of a broken window allows determination of the direction of impact. Also; a high velocity projectile always leaves a hole wider at the exit side of the glass. The size of the hole itself is not necessarily indicative of the size of the projectile. Also; a second fracture will always terminate when it meets an existing line of fracture; which allows for determination of sequence of events if more than hole is made in a piece of glass.
Materials
- pane of glass with holes
Procedure
- Carefully examine the pane of glass. Determine a) which side of the glass was struck by the projectiles and b) which hole was created first.
- Record your answers and justify them in your notebook.
APPLICATION OF KNOWLEDGE SCENARIO
A burglary has been committed by breaking the window in the back door of a house to allow the thief to reach in and unlock the door. The back hallway has no carpet. A suspect is apprehended and his living quarters searched. A few small glass fragments are found embedded in the soles of his sneakers. The suspect works in a body shop and explains that there is always broken headlight glass on the shop floor. The small fragments of glass recovered from the suspect’s shoes may be associated to the crime scene or the body shop by comparing physical properties of the glass.
Your CSI team receives an envelope of evidence containing three containers; each containing glass evidence. The first is from the scene of the burglary; the second from the body shop where the suspect works; and the third from the soles of the suspect’s shoes.
In your notebook; describe how you will determine whether the glass evidence connects the suspect to the burglary. Carry out the tests and record the results in your notebook.
Complete your Crime Report paperwork and Expert Witness document. Make sure you define the following terms in your document so a jury will understand them.
a) fluorescence
b) density
c) specific gravity
d) refractive index
e) class evidence
Submit your notebook to determine if you will receive your Glass Evidence Certificate of Competence.

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• LINT
• Integrated science

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Online / Virtual