Forensics For Dummies. Douglas P. LyleЧитать онлайн книгу.
you can find out about many but not all of its concerns. You may use this book as a reference and as a springboard for further investigation. The next time you see a news report, read a mystery novel, or watch a movie involving a crime, you can turn to this book to obtain a better understanding of the science behind the story.
Part I
Cracking Open the Case
In this part …
✔ Discover how forensic science works.
✔ Find out who makes up the forensics team and what they do.
✔ Figure out how to properly collect and protect evidence at a crime scene.
✔ Understand the inner workings of a criminal mind.
Chapter 1
Understanding the World of Forensic Science
In This Chapter
▶ Defining forensic science and checking out its origins
▶ Understanding why the principle of evidence exchange is important
▶ Unveiling how forensic science is organized
▶ Revealing what services a crime lab offers
Turn on the TV any night of the week, and you’ll find crime scene investigators, or criminalists, tracking down criminals, crime lab technicians evaluating evidence, and even forensic pathologists conducting autopsies on shows detailing cases real or imagined. I don’t think this newfound interest in all things forensic stems from some macabre fascination with death or a guilty enchantment with the criminal world. If you ask me, people simply are curious by nature and have a strong appetite for scientific knowledge. Remember everyone’s fascination with the space program not too many years ago? The cool tools and magical feats of forensic science, such as making fingerprints appear from nowhere, identifying suspects by their shoeprints, sniffing out a forger by the unique signature of a laser printer, and finding even the most obscure poisons, are proving equally fascinating.
In this chapter, you get your feet wet with the basic definitions and organizational elements of the field of forensic science. Most of the topics that I touch on here are explored further in the chapters that follow.
If you lived in ancient Rome, you’d head to the forum when you wanted to discuss the news of the day. The town forum was a community meeting place for merchants, politicians, scholars, and citizens that doubled as a center for public justice. Steal your neighbor’s toga, and the case would be tried at the forum.
The same tools and principles that drive scientific research in universities and identify cures in hospitals are used by forensic scientists to reveal how a victim died and, ideally, who was responsible. In the same way modern hospital laboratories employ professionals to deal with pathology (the study of diseases of the human body), toxicology (the study of drugs and poisons), and serology (the study of blood), modern forensic laboratories employ experts in forensic pathology, forensic toxicology, and forensic serology, all of whom use the principles and testing procedures of their medical specialties to help resolve legal issues and answer questions like
✔ When and how did the victim die?
✔ Does the suspect’s blood match the blood found at the crime scene?
✔ Was a suspect’s unusual behavior caused by drug use?
Integrating science into the practice of law
Not long ago identifying, capturing, and convicting criminals depended primarily upon eyewitnesses and confessions. The world was smaller, communities more closely knit, and the extent of travel basically only as far as you could walk. Whenever anyone witnessed a crime, he likely knew the perpetrator. Case closed.
Trains, planes, and automobiles changed all that. Criminals can now rapidly travel far and wide, and with this newfound mobility they are less and less likely to be recognized by an eyewitness. Besides, eyewitness evidence these days frequently is proven to be unreliable (see Chapter 3).
For law enforcement to keep pace with these changes, other techniques for identifying criminals had to be developed. Science came to the rescue with methods that depend less on eyewitnesses to identify perpetrators or at least link them to their victims or crime scenes. Fingerprinting (Chapter 5), firearms identification and gunshot residue analysis (Chapter 18), hair and fiber studies (Chapter 17), blood typing (Chapter 14), DNA analysis (Chapter 15), and many other scientific techniques now help solve crimes that would’ve remained unsolved in the past.
The marriage of science and law hasn’t been without its setbacks. Many scientific breakthroughs are viewed with suspicion, if not downright hostility, until they become widely accepted. And before a science can ever enter the courtroom, it must be widely accepted. It should come as no surprise that before forensic science could develop, science in general had to reach a certain level of maturity.
Drawing from other sciences
✔ The invention of the microscope enabled criminalists to analyze even the smallest bits of evidence and to see details in evidence that never before were imagined.
✔ The development of photography gave criminalists a crystal-clear representation of the crime scene without relying on memory or the slow process (and far less detailed results) of making drawings.
✔ The understanding of the physics of ballistic trajectories gave criminalists a much clearer idea of where a bullet may have come from, which, in turn, made crime-scene reconstruction more accurate.
✔ The discovery of blood typing and DNA analysis made matching suspect to crime scene far more exact.
✔ The expansion of our knowledge in basic chemistry allowed scientists to identify chemicals and poisons, particularly arsenic, and led to the development of forensic toxicology.
You witness a burglar sneaking away from a store late at night. You call the police, and when they arrive, you identify the thief as someone you know. That person is arrested. However, fingerprints from the store’s broken window, cracked safe, and tools used to open the safe don’t match those of the person you’ve identified. Instead, they match the fingerprints of a known safecracker. What do you think police, prosecutors, and more importantly, the jury are going to believe? After all, it was dark and raining, you were 100 feet away, you caught only a glimpse of the thief, and you’d just left a bar where you’d had a couple of drinks with friends. The fingerprints, on the other hand, match those of a known thief in each and every detail, meaning they came from him and only him. Which bit of evidence, the fingerprints or your eyewitness account, is more reliable?
This scenario represents what forensic science does, or at least attempts