Forensics For Dummies. Douglas P. LyleЧитать онлайн книгу.
in this book is designed to either identify perpetrators or connect them to the crime.
Starting out small: Basic forensic services
Properly identifying, collecting, documenting, and storing evidence are at the heart of the forensic services offered by virtually all law enforcement agencies, from village cops to major metropolitan police departments. They need the basic services in the list that follows to be able to investigate and solve crimes and to convict the criminals who commit them:
✔ Evidence collection unit: This crime-scene investigation unit collects and preserves evidence from the crime scene and transports it to the lab. Regardless of whether they’re individual police officers or highly trained professionals, members of this unit expose and lift latent fingerprints (Chapter 5), collect hair and fibers (Chapter 3), and gather any other articles of evidence at the scene.
✔ Photography unit: The photography unit takes pictures of the crime scene, all evidence, and the body (whenever one is present). These photos are crucial, serving as blueprints for crime-scene reconstruction and an excellent format for presenting evidence in the courtroom. Turn to Chapter 3 to find out more about photographing a crime scene.
✔ Evidence storage: A secure place for storing and preserving the evidence is essential. Evidence usually is stored in a locked room with restricted access that is housed at your local police station or sheriff’s department. Evidentiary materials are kept in storage for years or even decades, and the chain of custody (see Chapter 3) must remain unbroken throughout that time, or the evidence can be compromised, losing its value.
Looking at physical forensic science
Tracking down trace evidence, checking the characteristics of bullets fired from a gun, examining the penmanship of a signature on an important document, and evaluating the swirling ridges of fingerprints under a microscope all are part of the physical side of forensic science.
✔ Trace evidence: Any small item of evidence, such as hair, fiber, paint, glass, or soil, for example, that places the suspect at the scene of the crime or in direct contact with the victim is considered trace evidence. Matching glass fragments found on the victim of a hit-and-run motor-vehicle accident to glass from the broken headlamp of the suspect’s car is a prime example. Find out more in Chapter 17.
✔ Firearms examination: Firearms examination deals with the identification of weapons and the projectiles they fire, including ammunition, fired bullets, shell casings, and shotgun shells. Firearms experts use a microscope and various types of chemical analysis to identify the type of weapon used to commit a crime and match any bullets fired from that weapon or shell casings to a suspect weapon. I cover firearms examination in Chapter 18.
✔ Document examination: Whenever an important written document’s age or authenticity is in doubt, a document examiner uses handwriting analysis to match handwriting samples to questioned documents or signatures. Document examination also may include analyzing the physical and chemical properties of papers and inks or exposing indented writing (the impressions made on the page beneath one that was written on). Typewritten or photocopied documents that may have been altered also fall under the document examiner’s area of expertise. Check out Chapter 19 for the details.
✔ Fingerprint examination: Fingerprint examiners match prints to the fingers, palms, or soles of the people who left them at the crime scene. A print found at a crime scene can be compared with another taken from a database or from a suspect, victim, or bystander. Chapter 5 tells you all about fingerprint examination.
Delving into biological forensic science
Forensic science deals not only with physical evidence but also with biological evidence, which may take the form of a corpse, skeletal remains, drugs and poisons, teeth, bite marks, insects, and plant materials, to name a few. It also includes analysis of the criminal mind. Biological evidence is often what makes or breaks a case.
For example, an autopsy (postmortem examination of the body, which is discussed in Chapter 9) may reveal the nature and cause of any injuries, the presence of any poisons, and ultimately why and how the victim died. These findings alone may lead to the perpetrator. Blood and DNA analysis can positively identify suspects and link them to crimes. DNA and dental pattern records can be used to identify an unidentified corpse, and plant and insect evidence can reveal the time of death and link a suspect to the crime scene. Find out more about these sciences and the people who specialize in them in Chapter 2.
Although they use much of the same equipment and follow similar research procedures, forensics (crime) labs are quite different from medical (clinical) labs. The latter deal with the living by carrying out testing aimed at diagnosing and treating the sick. On the other hand, forensics labs are geared toward testing evidence with the hope of establishing links between a suspect and a crime.
Creating the first crime lab
In 1932, Goddard helped the Federal Bureau of Investigation (FBI) establish a national forensics laboratory that offered virtually every forensic service known to law enforcement across the United States. It, too, served as a model for future state and local labs. Now many states have networks of regional and local labs that support law enforcement at all levels.
During the height of Prohibition, gang warfare raged over control of the illegal alcohol trade that sprang up in many U.S. cities. None was bloodier than the war between Chicago rivals Al “Scarface” Capone and George “Bugs” Moran.
On the night of February 14, 1929, seven of Moran’s men were waiting for a shipment of hijacked liquor in a warehouse on Chicago’s Clark Street. Unbeknownst to them, the shipment was a setup orchestrated by Capone in an attempt to kill his chief rival, Bugs Moran. Moran was supposed to be at the warehouse, but he arrived late. When he got there, he saw a police car pull up and five officers enter the warehouse. Moran retreated and heard machine gun fire, then saw the five cops come out and drive away.
The real police arrived and found that each of the seven men had been shot numerous times. They recovered 70 shell casings. Bullets later were recovered from the victims. Cardiologist Dr. Calvin Goddard, who became famous during the Sacco and Vanzetti case (see Chapter 20), was called in because of his expertise in firearms identification. He determined that the shell casings were from Thompson submachine guns. Using the newly developed comparison microscope, he tested casings from Thompsons belonging to police and determined that none of them were the murder weapons. Goddard’s findings