The influence of forensic evidence on the case outcomes of homicide incidents

ObjectiveIn spite of the growth of forensic science services little published research exists related to the impact of forensic evidence on criminal case outcomes. The present study focused on the influence of forensic evidence on the case processing of homicide incidents.Materials and MethodsThe study utilized a prospective analysis of official record data that followed homicide cases in five jurisdictions from the time of police incident report to final criminal disposition.ResultsThe results showed that most homicides went unsolved (34.5% conviction rate). Only 55.5% of the 400 homicide incidents resulted in arrest of which 77% were referred to the district attorney. On the other hand, 94% of cases referred to the district attorney were charged. Cases were more likely to have arrests, referrals, and charges when witnesses provided information to the police. Suspects who knew their victims were more likely to be arrested and referred to the district attorney. Homicides committed with firearms were less likely to be cleared. The most noteworthy finding was that none of the forensic evidence variables significantly influenced criminal justice outcomes.ConclusionsThe study results suggest that forensic evidence is auxiliary and non-determinative for homicide cases.

Research Highlights►Ninety-seven percent of homicide incidents had physical evidence collected from the crime scenes. ►Only half of the 400 homicide incidents were cleared by arrest. ►The overall conviction rate was 34.5%. ►Forensic evidence variables did not have any influence on any stage of criminal case processing. ►Homicides committed with firearms were less likely to be cleared by arrest.