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.

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.

If you need to find out how a victim died or identify a piece of a plant found at a crime scene, you call on a forensic scientist trained in pathology or botany, respectively. Professionals who work in the various forensic biological sciences are among the most highly trained and skilled members of the forensics team.

Staging is when someone who's committed a crime attempts to make the scene look like something that it isn't. The most common staging scenario occurs when someone tries to make a murder look like a suicide or an accident. The suspect may move the body or clean certain areas. Say, for example, a husband strikes his wife in the head with a blunt object, killing her.

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.

No body means no crime, right? Maybe so, but more often it means a body was well hidden. When a body (and the critical evidence it provides) can't be found, investigators rely on a few time-tested techniques for unearthing it. This branch of forensics is a particularly interesting one, and it's growing all the time.

Because forensics is such a hot topic these days, millions of viewers are becoming armchair experts on that subject. But is Hollywood reliable? Sometimes yes, sometimes no. The quick death A gun is shot or a knife is thrown and down goes one of the bad guys, perhaps clutching his chest or taking one last dramatic breath, but either way, he's instantly a goner.

Locating evidence can be straightforward: Someone calls the police to report a burglary, and when the police arrive the victim invites them in and shows them the location of the pried-open window, the family safe, and the perpetrator's escape route. But, in other cases, the probable location of the evidence is not always associated with a crime scene, and police are not invited into the area where the evidence may be located.