Exploring the use of DNA evidence in homicide investigations: Implications for detective work and case clearance

Since the 1960s there has been a consistent gradual decline in national homicide clearance rates and the trend continued throughout the 1990s and into the 21st century, despite the development of DNA evidence. Although the media portrays DNA testing as an investigative "super weapon" for police, there is little empirical research examining its actual use by detectives or its impact on case clearance. This article examines New York Police Department (NYPD) case files for Manhattan homicides between 1996 and 2003 to investigate how often detectives used DNA evidence in the course of their investigations, as well as how its use influenced the likelihood of case clearance. Results suggest that DNA evidence was rarely used by NYPD detectives and that it was not related to case clearance. These findings suggest that NYPD detectives used DNA evidence as a "tool of last resort," relying on it only when all other investigative means had been exhausted. The authors conclude that the explanation for these findings is complex and that the diffusion framework may be helpful in understanding detectives' use of DNA evidence in New York and elsewhere.