Trails of Evidence: How Forensic Science Works
Overview
About
Trailer
01: Using Science—Crime Scene to Courtroom
Professor Murray opens the course by discussing her participation in a multifaceted homicide case that illustrates the many factors that go into a forensic investigation. Learn how the scientific method is rigorously applied in the field, and survey the topics you will cover in the course.
02: Crime Scenes and Forensic Evidence
Locard’s exchange principle holds that every contact leaves a trace. Starting with this rule, discover how a forensic scientist approaches a crime scene. Professor Murray suggests an experiment you can perform to understand the difficulty of finding evidence in an unfamiliar setting.
03: Fingerprint Science—Hands-Down ID
Explore the science of fingerprint analysis, which has been a tool of forensic investigators since the late 1800s. Learn the different coding systems for classifying fingerprints, the techniques for recovering prints where they appear absent, and the innovation of computerized matching.
04: Telltale Marks—Tools, Guns, and Ammunition
Many people know that a gun leaves telltale marks on the bullets it fires. But firearms evidence is only part of a much broader field called toolmark analysis. Examine the ways forensic scientists match a tool to the impressions it leaves on a surface it contacts.
05: Good Impressions—Shoes, Tires, and Skin
Continue your study of the crime scene by looking at the importance of forensic photography and the marks made by shoes, tires, and textiles. Professor Murray describes a case in which crucial clothing impressions on a body showed a death was accidental.
06: Forensics of Fibers, Paint, and Glass
Turn to examples of trace evidence that can clinch a case in court—as long as samples are properly handled and analyzed. Fibers, paint, and glass fragments sometimes have a vivid story to tell about their origin and the events that left them on a victim or at a crime scene.
07: Traces of Hair and Fur
Hair is one of the most commonly analyzed forms of trace evidence and may contain DNA that can pin down its source. Discover that the difficulty of DNA testing makes hair more often used to rule out suspects, since hair has distinctive characteristics that are easily observable.
08: Soil, Protist, Plant, and Animal Traces
Enter the field of wildlife forensics, which involves not just attacks by animals on people but the many ways that evidence from nature is used to solve crimes. Soils, wood, pollen, and animal traces can all connect a person or object to a crime scene.
09: Serology—Blood and Other Body Fluids
What does an investigator do when a murder scene has been scrubbed spotlessly clean by the perpetrator? TV dramas often get the facts wrong. Survey the arsenal of tests for body fluids that can uncover a hidden crime.
10: The Forensic Analysis of DNA
Learn how DNA profiling became the gold standard in both victim and perpetrator identification, even though humans have more than 99% of their DNA in common. Professor Murray discusses the landmark case in the United Kingdom that was the first to use DNA to convict a killer.
11: Forensic Toxicology of Drugs and Poisons
Enter the toxicology lab to learn how drugs and poisonous substances are detected, even in minute quantities. Trace the path of drugs through the bloodstream and understand their effects. Then see how forensic scientists use sophisticated tests to identify chemicals in a victim’s body.
12: The Forensics of Substance Abuse
In one recent year, drug overdoses accounted for 26,000 deaths in the United States. Focus on the forensics of this serious social problem. How are drugs of abuse classified? How do they affect the body? And which regulated substances are more commonly analyzed in the forensic chemistry lab, since they’re the most frequently encountered on the street?
13: Handwriting and Forgery Analysis
Examine the field of questioned documents, which involves both handwriting analysis and the more scientifically conclusive procedures of materials examination. Learn the tip-offs that someone is trying to duplicate the handwriting of another, and explore the ways that some famous fakes were unmasked.
14: Computer Forensics and Digital Evidence
Learn how forensic investigators extract evidence from computers, cell phones, and other electronic devices. Discover the importance of slack space on a hard drive, and review how GPS tracking solved one murder that ultimately led officials to link that killer to another murder over a decade earlier.
15: Structure Failure—Forensic Engineering
Whenever a bridge, building, or other structure fails, forensic engineers are called in to determine what went wrong, which may show whether a crime was committed. Focus on cases such as Boston’s deadly Great Molasses Flood in 1919 and the collapse of the World Trade Center Twin Towers in 2001.
16: Forensic Analysis of Vehicle Accidents
Apply Newton’s laws of motion to automobile accidents, discovering what skid marks, front-end damage, and other clues reveal about the cause of a collision. Close by considering two other types of vehicle accidents: an airline crash in 1994 and the Space Shuttle Challenger disaster in 1986.
17: Fire Science and Explosion Forensics
Probe the ashes of a smoldering building to find the telltale traces that can point to arson. Even the aftermath of a violent explosion leaves clues about what caused it. But first, it’s important to understand the physics of fire and explosives—and the motives of those who light the fuse.
18: Blood Evidence—Stains and Spatters
Even when a body is absent, blood leaves distinctive patterns that can tell investigators the nature of an injury, the type of weapon that made it, and sometimes the degree of culpability of the person who caused it. Review the role of blood evidence in the infamous Sam Sheppard murder trial.
19: The Science of Death
Begin a series of lectures on death and its aftermath by studying the end stages of life. Seldom as simple as portrayed on TV, death is a cascade of failures rather than a single event. Explore some of the many routes to this inevitable end.
20: Death Investigation—Algor, Livor, and Rigor
How can an investigator inspect a body and estimate the time of death? Follow the steps that the body’s systems take after life ends, including algor mortis, livor mortis, and rigor mortis. Each of these processes can help signal when death occurred and also the likely circumstances.
21: Autopsy—Cause and Manner of Death
Step into the morgue to understand why and how a forensic autopsy is performed. The purpose is to determine the cause and manner of death, and often to identify the victim. Much like exploratory surgery, no two autopsies are the same.
22: Decomposition—From Bugs to Bones
When bodies are in a state of advanced decomposition, forensic entomologists use knowledge of insect life cycles to estimate the time since death. Discover that a research center known informally as the Body Farm has turned this gruesome subject into a science.
23: Forensic Anthropology—Skeleton Stories
Study the science behind skeletons, learning how investigators read the clues in bones for signs of age, sex, ancestry, and trauma. Human skeletons vary widely, even in the number of bones in an individual. The standard textbook figure—206—is only an average.
24: Forensics of Teeth and Bite Marks
Forensic odontologists are dentists trained to use their knowledge of teeth in two ways: to identify unknown persons and to interpret bite mark evidence on victims. Learn how dental patterns can be compelling evidence and led to the murder conviction of serial killer Ted Bundy in 1979.
25: Police Sketches and Facial Reproductions
From wanted posters in the Old West to today’s digital face reconstructions, forensic art is an enduring tool of law enforcement. Explore the techniques artists use to create a recognizable human likeness based on limited information, and learn about the careful approaches these artists must take when interviewing witnesses.
26: Interview, Interrogation, Intelligence
Turn to a key component of police work that underlies all forensic investigations: evidence provided by people. Learn the differences between interviewing, interrogating, and gathering intelligence. Effective interrogation is a far less adversarial process than is portrayed on TV.
27: Forensic Profiling—Who, How, and Why?
Explore one of the most controversial aspects of forensics: personality profiling. Profiling can greatly narrow the field of potential suspects and aid in capturing criminals. Review cases in which this technique proved spectacularly successful and also tragically misguided.
28: Human Memory and Eyewitness Accounts
Eyewitness testimony carries enormous weight in court. But how reliable is it? Professor Murray describes a “crime” that she stages in front of her students to test their reliability as witnesses. Her experiences in the classroom match the unsettling findings of studies.
29: Criminal Minds—Psychology and Psychiatry
Dealing with human behavior is at the root of the legal system. Delve into forensic psychology and forensic psychiatry by studying the disturbing case of serial killer Jeffrey Dahmer. Then look at how the criminal justice system evaluates insanity pleas, separating frauds from the genuinely mentally ill.
30: When Forensic Evidence Is on Trial
Forensic evidence must be collected, prepared, and analyzed with care, since it may wind up in court. What happens when it does? Review the history of scientific evidence, its changing acceptance by the courts, and efforts today to develop uniform standards in forensics that apply throughout the country.
31: Forensic Scientists and Expert Testimony
Both sides in a legal dispute have the right to good science, and Professor Murray has testified for both the prosecution and defense in different trials. Hear some of her experiences, and examine the many career pathways to becoming a forensic expert.
32: Comparing Crimes and Crime Labs
Turn to the subject of crime itself, exploring the different categories of homicide, assault, and property offenses. The disparity in technology around the world means that forensic science practices vary. Close by looking at a typical high-tech crime lab and the types of evidence that move through it.
33: Crimes—Nobody’s Supposed to Get Hurt
Get practical forensic experience by learning how to calculate when an individual is over the alcohol limit for drunk driving. Then explore the role of forensics in cases of identity theft, arson, and a famous kidnapping in which an astute victim laid the foundation for snaring his captors.
34: Crimes—Killers of One, Killers of Many
Analyze four tragic cases that were solved with the help of forensic evidence: the killing of eight-year-old Sarah Payne in England, the Jeffrey MacDonald triple-murder case, a 17-year string of hospital killings that appeared to be natural deaths, and the BTK (“Bind, Torture, Kill”) murder spree in Wichita, Kansas.
35: Applications—Mass-Disaster Forensics
What is the experience of a forensic investigator in the aftermath of a mass disaster? Professor Murray recounts her role in the analysis of the 1994 crash of American Eagle Flight 4184. Learn how mass disasters are like monumental crime scenes, in which many forensic techniques come into play.
36: Applications—Identification Matters
One of the most emotionally satisfying aspects of Professor Murray’s work is identifying deceased unknown persons, helping to bring answers to a victim’s family. Finish your study of forensic science with examples of her work in this area, including a nearly 40-year-old cold case that she helped solve.