Understanding the Impact of Forensic Evidence on Homicide Clearance: An Analysis of Los Angeles Homicide Cases, 1990-2010

Homicide clearance rates have dropped considerably between the 1960s and 1990s, a period called the Great Decline. Recently researchers have argued that one of the factors leading to the Great Decline was the increase in prosecutors demand for forensic evidence to proceed with prosecution. Using a unique sample of 4,111 homicide investigator case files, or “murder books,” from 1990 to 2010 compiled and digitized by the Los Angeles Police Department, this research examines the impact of forensic evidence on homicide clearance. Forensic evidence had an independent impact on homicide clearance after controlling for victim characteristics, homicide circumstances, and contextual variables. The collection of fingerprints and gun casings was associated with increased odds of clearance. Other contextual, victim, and circumstance variables on homicide clearance remained important for predicting clearance and are discussed.