Nationwide, 14 percent of open homicide cases and 18 percent of open rape cases contain forensic evidence that has not been sent to a crime lab for analysis, according to a new study conducted by RTI International for the Office of Justice Programs' National Institute of Justice.

The national survey of more than 2,000 state and local police agencies also found that fewer than half of police departments (43 percent) have computerized systems in place for tracking forensic evidence inventory.

Among the reasons cited for not submitting forensic evidence for analysis were:

* 44 percent reported that evidence is not submitted for analysis unless a suspect has been identified

* 15 percent of law enforcement agencies reported that they may not submit forensic evidence to a lab if the analysis was not requested by a prosecutor

* 11 percent said they did not submit evidence because they felt the lab was not able to produce timely results

* The survey also revealed that evidence retention policies and practices vary widely from jurisdiction to jurisdiction.

The "Survey of Law Enforcement Forensic Evidence Processing" was conducted by RTI International and funded by the National Institute of Justice, the research, technology and evaluation component of the Department of Justice.