Cheat Sheet

Forensics For Dummies

From Forensics For Dummies by Douglas P. Lyle

Using science to help solve crime is what forensics is all about. Science and safety rule everything from how a law enforcement officer approaches a crime scene to what to put into a forensic toolbox. Forensics comes into play when civilians witness a crime as well as when a professional medical examiner determines cause of death. And, because forensics is about solving crime, knowing current crime statistics from the FBI can help focus on the most common ones.

How to Approach a Crime Scene to Protect Forensic Evidence

Forensics, which is basically the practice of applying science to crime, dictates that certain procedures be followed at the scene of a crime. The first officer to arrive at a crime scene must take certain steps to preserve life and evidence. Only after these duties are performed can analysis of the scene begin. These steps include:

  1. Assuring his or her personal safety and that of any fellow officers, victims, suspects, and witnesses.

  2. Offering first aid to any injured persons and calling for medical help.

  3. Calling for backup and any ancillary personnel, such as detectives, crime-scene investigators, coroner’s office personnel, and firefighters, that are deemed necessary.

  4. Cordoning off the scene to protect the integrity of any evidence.

  5. Detaining and separating any suspects or witnesses whenever possible.

  6. Establishing a security log for any and all persons who enter or leave the crime scene.

What to Do if You Witness a Crime

Part of forensics is gathering reports from eyewitnesses, and who knows, you may be an eyewitness to a crime. You could be going to the store or a movie, dropping the kids off at school, or sitting at your desk at work, and it happens — a crime occurs right before your eyes. Follow the tips in this list if you witness a crime:

  • Protect yourself. Run, call for help, or hide. Do what is necessary to keep yourself out of harm’s way.

  • Help others. Offer first aid to anyone who’s injured.

  • Call for help. As soon as possible dial 911 to report the crime and to summon medical help.

  • Don’t touch or move anything. Remember that anything you touch or move can damage or contaminate critical evidence.

  • Pay attention. Take a deep breath, relax, and look around. Notice people, what they look like, what they’re wearing, any distinguishing marks they have, and what they’re doing. Notice vehicle make, model, and license number, or any other distinguishing details, if possible.

  • Wait for the police. When the police arrive, direct them to the crime and to any injured parties. Tell them exactly what you witnessed and answer all questions truthfully. Be careful to relate only what you know and don’t attempt to help by filling in any gaps with what you believe should be true.

FBI Crime Statistics

Without crime, you’d have no scope for your interest in forensics, although, being an upstanding citizen, you’d trade your forensics skills for a crime-free country in a heartbeat, right? Given human nature, you’ll never have to make that trade. Crime is a common occurrence in the United States, and the FBI maintains a database of all reported crimes throughout the country. The most recent complete-year figures for 2008 are shown in the following table:

Crime Number of Criminal Acts
Violent Crime 1,382,012
  Murder/Manslaughter   16,272
  Rape   89,000
  Aggravated assault   834,885
  Robbery   441,855
Property Crime 9,767,915
  Burglary   2,222,196
  Larceny-theft   6,588,873
  Auto Theft   956,846

Source: Federal Bureau of Investigations, “2008 Crime in the United States”

How to Stock a Forensics Toolbox

Crime scene investigators and forensics specialists are called to all types of crime scenes and at all hours. If you’re an investigator, you need certain tools and equipment to perform your duties, and a well-stocked toolbox that contains the items you most often need is a necessity.

The box may literally be a tool or tackle box, but can be anything you can easily carry to the scene of a crime. Your toolbox should contain the items in the following list:

  • Crime-scene tape to cordon off the area

  • A flashlight

  • Latex gloves and paper shoe covers

  • A magnifying glass and tweezers for collecting trace evidence

  • A pen, logbook, and sketchpad

  • Measuring tapes and rulers

  • A camera with black & white and color film and several different lenses

  • An assortment of paper, plastic, and glass containers to store collected materials

  • Sealable evidence bags

  • Portable alternative light sources — laser, ultraviolet, and infrared

  • Basic fingerprint kit with powders and lifting tape

  • Casting kit for three-dimensional shoe and tire impressions.

  • Gunshot residue detection kit

  • Chemicals to locate occult bloodstains — such as Luminol

  • Serology kit for sampling blood and other biological fluids

  • Rape kit

Forensic Duties of a Medical Examiner

In the case of murder, the medical examiner (ME) may be the person who puts forensics to its purest use. An ME uses science to determine the cause, mechanism, and manner of death to help the investigation and solution of a murder. The ME determines

  • Cause of Death: What disease or trauma directly caused the victim’s death. Examples may be a heart attack, a gunshot wound to the head, or a drug overdose.

  • Mechanism of Death: What specific physiological effect of the cause of death actually led to the cessation of life. For example, a heart attack victim could die from a deadly change in heart rhythm or from severe damage to the heart muscle, leading to shock. Here the cause of death is a heart attack, but the mechanism is a cardiac arrhythmia or cardiogenic shock, respectively.

  • Manner of Death: How the cause of death came about. The five manners of death are: natural, accidental, suicidal, homicidal, and undetermined. A gunshot wound (the cause of death) may have been accidental, suicidal, or homicidal, for example. Only deaths from disease are natural.

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