Ballistics
A study by Dr. William King and colleagues led to changes in the way police process ballistic evidence in crime labs.
Using data from 2012, the study found that ballistics imaging rarely contributed to identifying, arresting or sentencing of suspects because of lengthy delays in processing and the lack of detailed information immediately available to investigators. Ballistics imaging is a potentially powerful forensic tool that can help link crimes involving the same firearm using microscopic comparisons of cartridge casings.
However, the study based on 2012 data from 65 gun-related violent crime investigations in nine U.S. police agencies, found that ballistics reports took an average of 181 days to complete and required additional research by investigators to find relevant information. It also found that half of the suspects had been identified and one-third were arrested before a ballistics report was produced. Investigators said that ballistics reports contributed to identifying suspects in about 10 percent of cases, arresting a suspect in nearly 2 percent of cases and obtaining a plea bargain in about 5 percent of cases.
“Our results indicate that in 2012, the utility of ballistics imaging reports for investigators was limited, and investigators did not often use these reports during the course of an investigation,” said William King, a professor in the College of Criminal Justice at Sam Houston State University.
Following the preliminary publication of the study’s findings in 2013, many local agencies and crime labs began to collaborate to shorten processing times for ballistics evidence. “There is evidence that currently, labs and police agencies are utilizing ballistics imaging results to solve violent crimes, in part because of our study results,” said King.
The study suggested that improvements in people, processes and technology may help to speed up results. In the meantime, investigators use ballistics reports as one piece of information in complex cases.
“As one robbery detective stated, ‘When I work an investigation, it's like I'm hopping down a bunny trail. I want to gather as much information from anyone and anywhere as I can. Anything might prove helpful It may be that investigators like hit reports because of the possibility of illumination, not because the hit reports ‘crack the case’ or yield a tremendous insight,” said King.
Forensic Evidence and Criminal Investigations: The Impact of Ballistics Information on the Investigation of Violent Crime in Nine Cities by King, Bradley A. Campbell, Matthew C. Matusiak and Charles M. Katz, was published in the Journal of Forensic Science.
