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Misconduct by government officials is a factor in 54% of wrongful convictions, study finds

(CNN) Ronnie Long walked out of a North Carolina prison late last month after serving 44 years for a crime he had long said he didn't commit.

The 64-year-old Black man was convicted in 1976 of raping a White woman and burglary. But that conviction was recently vacated by a federal judge, who cited a "troubling and striking pattern of deliberate police suppression of material evidence," including semen samples and fingerprints from the crime scene that did not match Long's.

A study published September 1 finds that Long is far from alone, and that misconduct by government officials has contributed to 54% of false convictions of defendants who were later exonerated in the past three decades, with police misconduct being a factor in 35% of such cases.

The report was produced by the National Registry of Exonerations, a joint project by the University of Michigan Law School, Michigan State University College of Law and the Newkirk Center for Science & Society at University of California Irvine that tracks exonerations in the United States.

The 185-page study examined 2,400 exonerations in the registry dating back to 1989. It grouped officials' misconduct into five categories, including witness tampering, misconduct in interrogations, fabricating evidence, concealing exculpatory evidence and misconduct at trial.

In Long's case, the ruling vacating his conviction did not declare his innocence and left that question up to a lower court to decide. But he maintains his innocence, and according to the National Registry of Exonerations, the charges were dismissed by the district attorney's office and he was exonerated, in part due to misconduct by government officials.

In addition to police, prosecutors committed misconduct in 30% of the cases examined, the study says. Misconduct by forensic analysts was a factor in 3% of cases, while misconduct by child welfare workers was a factor in 2% of cases.

Most cases involved more than one type of misconduct, the study says. Sometimes the misconduct by officials was purposeful, like lying in court. But other times the misconduct was unintentional.

The study says that Black defendants were most impacted by officials' misconduct. Among cases involving Black exonerees, the rate of misconduct was 57%, compared to 52% among White exonerees. Misconduct was committed in 87% of cases against Black exonerees who were sentenced to death, compared to 68% of their White counterparts.

Ninety-three innocent defendants were sentenced to death, in part, due to misconduct by officials, the study says.

As to why this type of misconduct might be occur in the first place, the study concludes that it's a "systemic" issue. It points to "pervasive practices that permit or reward bad behavior," a lack of resources and "ineffective leadership by police commanders, crime lab directors and chief prosecutors."

CNN's Harmeet Kaur contributed to this report.