A recent survey, conducted by the authors, of approximately 200 FBI National Academy (NA) attendees found that 95% of those who investigated homicides often or always review the related 911 calls. These law enforcement officers stated that the calls provide a valuable starting point as the first witness statements for a case and allow investigators to review the demeanor and reactions of the caller. The calls also capture additional information that may help later, such as the voices of other people on the scene.
Officers may analyze voice modulation — change in tone or pitch — to interpret the veracity behind a caller’s description of an event. Is this a reliable measure of deception? What about minimization — an individual’s attempt to downplay culpability in an incident? Can investigators accurately decipher modulation and minimization from 911 calls?
While many factors go into the analysis of a 911 call, these two characteristics are typically recommended for investigators to analyze.1 In this article, the authors review the literature on voice modulation and minimization in 911 calls as deception indicators and then offer suggestions on using these calls to support homicide investigations.
Read more at FBI Law Enforcement Bulletin
