Chapter 13 - Beyond reasonable doubt: how to think like an expert detective

Abstract

The success of criminal investigations depends to a great extent on investigators' ability to make the correct decisions at the correct time. Unfortunately, investigators face a number of obstacles to optimal decision-making, including time pressure, emotional involvement, and expediency-promoting occupational norms, all of which have been shown to debilitate investigators' ability to objectively process case-relevant information and evidence. A particular challenge, amplified by the aforementioned factors, is to resist going from the process of “suspect identification” to “verification” at a too early stage of the investigation. That is, although an investigation with potential for prosecution must at some point start building a case against a suspected offender, doing so prematurely may be extremely harmful as evidenced by numerous miscarriages of justice. First of all, an expert detective has to acknowledge and counteract the inherited risk of verification bias we all are subjected to and which is found to be somewhat institutionalized at all stages of the criminal justice process. Next, detectives have to methodologically operationalize the fundamental legal threshold in criminal cases—guilt should be proven beyond reasonable doubt. In cases of some complexity, this can only be done by adhering to a method and a mind-set based on progressive attempted elimination of explanations consistent with innocence, very much like proposed by the fictional mastermind Sherlock Holmes. Thirdly, based on knowledge of how hard is it to consistently uphold such a deliberate mind-set for a human brain which Daniel Kahneman calls “a conclusion-jumping machine” expert detectives are in constant need of support from facilitating systems as well as cultures.