NCJ Number
215985
Journal
FBI Law Enforcement Bulletin Volume: 75 Issue: 10 Dated: October 2006 Pages: 12-19
Date Published
October 2006
Length
8 pages
Annotation
This second of two articles on factors in failed criminal investigations identifies types of probability errors in investigative decisions and organizational traps that can undermine investigations, followed by recommendations for investigators.
Abstract
The direction of an investigation is determined by a series of decisions by investigators and forensic scientists regarding what they believe to be true. Probability errors occur when investigative decisions are believed to be based on absolutes rather than probabilities. The probability that an investigative decision is correct must be weighted according to the volume and strength of data and evidence on which the decision is based. Among the types of probability errors are failing to take into account the probability that a coincidence has occurred in a combination of events rather than cause-and-effect based on criminal planning. Another type of probability error is to "double count" the weight of evidence that points toward a particular suspect; for example, when more than one person provides information that comes from the same source, this does not multiply the weight of the evidence. Other probability errors are to impose general patterns of behavior or offender characteristics on a specific case or to decide that there is only one logical conclusion from a set of evidence when there may be other equally or more probable explanations. Organizational traps that can undermine investigations pertain to inflexible, unexamined, media-responsive organizational subcultures that emphasize rapid resolution of cases with limited resources. Six strategies are suggested for avoiding investigative failures, including encouraging the members' investigative teams to offer and test multiple alternatives that might explain evidence in a case. 23 notes