Murder case challenges longstanding ballistic tests
CHICAGO — When Illinois jurors convicted Patrick Pursley of murder, they relied on an expert’s assurance the scratches and dents on bullets and shell casings from the crime scene proved they could only have come from Pursley’s gun.
More than two decades later, technological advances have eroded confidence in ballistic experts, and the analyst who testified against Pursley is no longer so sure of his findings. Now Pursley is awaiting a new trial, and the case could become the first in which a database used to help put countless criminals behind bars sets someone free. The issue could also pave a new path for other convicts to challenge convictions.
“I knew that this could exonerate me because there would be no bias. It would just be a computer algorithm saying it is or it isn’t,” said Pursley, who was convicted in 1994.
Now 51, Pursley represented himself for more than a decade and convinced Illinois legislators to update the law to let him retest the evidence using a more advanced system that links shell casings to guns — a tool that became available five years after his conviction.
A judge agreed the results from the Integrated Ballistic Identification System cast doubt on the trial expert’s conclusions. Pursley was granted a new trial in March.
The system known as IBIS compares high-resolution, multidimensional images of shell casings to find markings unique to a specific weapon. In Pursley’s case, it failed to match the gun police took from him to the bullets that killed 22-year-old Andy Ascher on April 2, 1993, in Rockford, northwest of Chicago.
It’s not clear how many cases like Pursley’s exist. So far, Illinois is the only state that allows the system to be used in appeals. Pursley is the first to use the 2007 law, “which could set an important precedent for others,” said Andrew Vail, an attorney at the law firm representing Pursley for free along with Northwestern University’s Center on Wrongful Convictions.
Steven Drizin, the assistant dean at the center, said he’s hopeful other states will update their laws.
“This is pretty much uncharted territory and it shouldn’t be,” Drizin said.
The images placed into IBIS are stored in the National Integrated Ballistic Information Network managed by the Bureau of Alcohol, Tobacco, Firearms and Explosives. Since 1999, the 2.8 million images entered into the database have helped investigators identify suspects in countless homicides nationwide, according to the ATF, which lists success stories on its website .
Winnebago County prosecutors are appealing the judge’s ruling for a new trial. They maintain Pursley was the man who approached Ascher and his girlfriend while they sat in a car and demanded money. Ascher’s girlfriend told police she was looking for cash in her purse when she heard two shots and saw Ascher slouch down in the driver’s seat. The gunman wore a blue ski mask and black gloves, according to Ascher’s girlfriend, but police never found either item.