Douglas P. Lyle

Ever wonder just how prevalent various crimes are? Or about what you should do if you witness a crime? This Cheat Sheet covers that and more, such as how investigators approach a crime scene and the tools they bring to bear in their search for clues, as well as how the medical examiner or coroner determines the cause, mechanism, and manner of death.

For those interested in digging deeper into the science and techniques of forensic science and criminal investigation, here are some excellent resources for further study. The Writers' Forensics Blog This is DP Lyle, MD's blog. Though originally geared toward writers of crime fiction, this blog is followed by forensics industry professionals and those who have an interest in crime and forensic science.

The medical examiner (ME), when dealing with death, is charged with determining the cause and manner of death. The cause is what actually led to the death; the manner is by whose hand and for what purpose the death occurred. These manners can be natural, accidental, suicidal, homicidal, or undetermined, the latter being designated when the ME can't assign the death to one of the other manners with any degree of certainty.

Forensic analysis of most physical and biological evidence is conducted for two purposes: identification and comparison. Identification determines what exactly a particular item or substance is. Is that white powder cocaine? Is that brown stain dried blood? After testing, a forensic examiner may state that the substance in question is present, not present, or that testing was inclusive and the presence of the substance can't be ruled in or ruled out.

Many criminals attempt to damage, alter, or remove their fingerprints to avoid identification or connection to prints found at a crime scene. From John Dillinger to more "common" criminals, these efforts are usually unsuccessful. Still, if, after leaving prints at a scene, the perpetrator successfully alters or damages his prints, the fingerprint examiner may not be able to make a reliable match.

On April 5, 1994, the body of Kurt Cobain, singer/songwriter for the grunge rock group Nirvana, was found in an over-the-garage apartment at his home. His wife, Courtney Love, was in another state at the time of his death, so he was home alone. Or at least it appeared that way. He was found lying on his back, with a shotgun resting on his chest, and an obvious shotgun blast beneath his chin was the cause of death.

The most important function of the medical examiner in any death investigation is determining the cause, mechanism, and manner of death. Here are definitions of each of these terms: Cause of death: The disease or trauma that directly caused the victim's death. Examples include a heart attack, a gunshot wound to the head, or a drug overdose.

Crime is a common occurrence in the United States. The FBI maintains a database of all reported crimes throughout the country. It's called the Uniform Crime Reporting (UCR) Program. During 2013, nearly 10 million criminal acts were reported. These crimes consisted of the categories and numbers shown in the following table.