As the science around DNA testing advances and becomes more commonplace in courts it reveals weaknesses in other forms of forensic evidence and expert testimony that impact convictions in Arizona and around the nation.
According to the Innocence Project, there have been 330 post-conviction exonerations related to DNA evidence in the United States since 1989 and 263 since 2000. Twenty of the 330 exonerated persons had served time on death row.
While DNA evidence led to the exoneration of 330 wrongfully convicted people it also led to the identification of 162 people who were found to be the actual perpetrators of the crimes, the project said.
The Innocence Project concludes the leading causes to the 330 post-conviction DNA exonerations were eyewitness testimony, a factor in 70 percent of cases, non-validated or improper forensic science, a factor in 47 percent of cases, and informants, a factor in 15 percent of cases.
A fourth cause was identified as false confessions. It was a factor in about 28 percent of the cases but when only focusing on homicide cases, false confessions played a factor in 63 percent of the cases.
The percentages total more than 100 percent since a single case may contain more than one factor that led to a wrongful conviction.
In 2002, Ray Krone was exonerated for the 1991 murder of Kim Ancona in Phoenix. His exoneration was due to a 2001 law that allowed for the testing of DNA in past convictions. Krone would become the 100th person in the United States to be exonerated after having been sentenced to death since 1976.
The then Maricopa County prosecutor, Noel Levy, presented bite mark evidence and an expert witness as the proof of his guilt.
“He testified that the marks on the body matched my teeth, that my teeth were unique as a result of that car accident, that those marks happened at the time of her death and that made me, Ray Krone, without a doubt the murder,” Krone said. ” I was called the snaggletooth killer in the papers.”
Later investigations showed the state paid the bite mark expert $50,000 to testify while the state appointed private attorney representing Krone was only given $5,000 to mount his defense.
In 2002 he was exonerated after DNA testing excluded him from the sample while at the same time identifying Kenneth Phillips who is now serving time for the murder of Ancona.
With post conviction DNA testing showing the fallibility of expert and eyewitness testimony as well as the disparity between private and public defender cases, the reliability of past convictions and current convictions without the use of DNA have become increasingly questioned by legal advocates.
Carrie Sperling, an associate professor of law at the University of Wisconsin and co-director of the Wisconsin Innocence Project, credits much of the questioning for previously relied on forensic evidence to the results of DNA testing.
“I really do believe that their idea of using DNA in that way has created, if not, fueled a revolution in the criminal justice system that can’t be understated,” Sperling said. “It is the foundation for questioning all the rest of the forensic sciences.”
One report has become a source of contention between the two sides of the judicial process. Defense attorneys and their advocates look to the 2009 National Academy of Sciences report as a document that questions the ability of using some non-DNA evidence in convictions and some in prosecution look on the document as a politically motivated report with questionable findings.
The NAS report does claim advances in DNA technology, as well as other areas, have shown some forensic sciences to be a useful tool for investigations and is the reason many unsolved cases have been able to identify a perpetrator.
It also claims the same advances have shown where forensic science analysis may have led to the wrongful conviction of innocent people.
“This fact has demonstrated the potential danger of giving undue weight to evidence and testimony derived from imperfect testing and analysis,” the report said. “Moreover, imprecise or exaggerated expert testimony has sometimes contributed to the admission of erroneous or misleading evidence.”
“What do we do now, now that the National Academy of Sciences has said that almost every one of the forensic sciences is unreliable or invalid in matching a bit of evidence to a particular person or perpetrator,” Sperling said. “What do we do in the criminal justice system about this, what do we do knowing that thousands and thousands and thousands of convictions have relied on that kind of evidence.
“What do we do knowing that there’s not DNA in many of the cases that we have, either it doesn’t exist or it doesn’t play a role in the case,” Sperling asked.
The conclusions Sperling drew from the NAS report were countered by Kathleen A. Mayer, chief legislative liaison, Pima County Attorney’s office, and Thomas L. Bohan, past president of the American Academy of Forensic Sciences.
“I would point out that the NAS report is vastly overstated in its conclusions and is a very political document in my judgment,” Mayer said.”There has been a criticism of forensic science for 20 years and it comes largely from law professors … and other academics who do not and have never set foot in a forensic science laboratory.”
For Bohan the disagreement is the idea that the evidence from forensic science is not valid or reliable.
“The report does not say these techniques are invalid, the report said they have not been validated and that’s a very important distinction,” Bohan said. “The fact is that the people who are true scientists who work in this field, and I consider myself one of them, were not surprised because we knew this.
“They had not been validated in the sense of what we consider validation in science,” Bohan said.
Sperling would later agree it would be more accurate to say the report claims the forensic sciences in question have not yet been validated rather than invalid, she said.
In response to the problem of wrongful convictions, a few prosecution offices around the nation have set up Conviction Integrity Units designed to find and correct past convictions of innocent people through reinvestigation of new and credible evidence. A major from of evidence being previously untested DNA evidence.
In October 2014, Pima County established a Conviction Integrity Unit that is tasked with reviewing legitimate claims of innocence and reinvestigating cases that meet their criteria.
To this date, Pima County has the only integrity unit in Arizona. None of the cases reviewed by the county’s Integrity Unit has resulted in exoneration.
The use of DNA evidence has become a key factor in exonerating those who have been convicted through forms of evidence that has falsely linked people to crimes they did not commit. This important new tool in post-conviction review is highlighted by Sperling.
“For goodness sake, we thought bite mark evidence was, you know, you could say it was a match,” Sperling said. “The only reason we don’t think that anymore is because of DNA testing.
“The only reason we don’t believe a lot of things we used to believe in trials — hair analysis, blood analysis, in different cases, all sorts of finger prints — is because of that work of using DNA to go back in and look at old convictions,” Sperling said.
Jorge Encinas here is a reporter for Arizona Sonora News, a service from the School of Journalism with the University of Arizona. Contact him at email@example.com