Note
"Supported by grant ... awarded to the Center for Research in Law and Justice, University of Illinois at Chicago Circle, ..."
On cover: Research report.
Summary
This report describes the findings of a study on the uses of physical evidence in criminal investigations in four US cities, the effects of such evidence on the solution of crimes and on the apprehension and prosecution of offenders. The study was based on 1,600 investigations in which physical evidence was collected and examined and on 1,100 cases where physical evidence was not used. The authors explain the process that controls the recognition, collection, and examination of physical evidence and describe evidence from the 1,600 sample cases. They identify the most frequently collected types of evidence and discuss variables (such as the time lapse between discovery of the crime and its report to the police) that affect evidence gathering. Characteristics of criminal incidents that help to explain the types and quantities of evidence collected are discussed, and rates of clearance, charging, and conviction are compared in the presence of absence of physical evidence. Evidence is shown to have a substantial effect on robberies (when there are no witnesses and no suspects) and burglaries (when a witness is located, but there are no suspects), but a negligible effect on assaults. Policy recommendations for police agencies are provided. (NCJRS)
Contents
1. Project background and overview. -- 2. Physical evidence and the investigation of crimes: a brief summary of the literature. -- 2.1.Physical evidence and crime laboratory studies. -- 2.2. Investigative studies. -- 2.3. Judicial outcomes of arrests. -- 3. Characterizing offenses where physical evidence is collected and examined. -- 3.1. Introduction. -- 3.2. The criminal offense and its report to police. -- 3.3. Taking the preliminary report. -- 3.4. The decision to investigate. -- 3.5. Search of the scene for evidence. -- 3.6. Submission of physical evidence: procedures and purposes. -- 3.7. Case outcome. -- 4. The investigative uses of physical evidence. -- 4.1. Introduction. -- 4.2. Decision to examine the evidence. -- 4.3. The results of laboratory testing. -- 4.4. Feedback and value of the scientific results to users. -- 5. Physical evidence and laboratory results. -- 6. The role of scientific evidence in the clearance and prosecution of criminal cases. -- 6.1. Introduction. -- 6.2. The evidence and no-evidence samples. -- 6.3. Physical evidence and clearance rates. -- 6.4. Disposition of arrests. -- 6.5. Plea bargaining and charge reduction. -- 6.6. Utility of fingerprint evidence in burglaries. -- 6.7. The role of physical evidence in drug cases. -- 6.8. Homicides, rapes and arson. -- 7. Estimating the effects of physical evidence on clearance and conviction using log-linear analysis. -- 7.1. Introduction. -- 7.2. The effects of physical evidence on clearance. -- 7.3. The effects of physical evidence on conviction. -- 8. Conclusions, policy recommendations and future research.