How Wrongful Convictions Happen and How They Get Undone

Leonard Mack was convicted in 1976 of rape and weapons charges in Westchester County, New York, and served about seven and a half years in prison. On September 5, 2023, his conviction was vacated after new DNA testing produced a database hit to another man, who, according to the Innocence Project, then confessed. The Innocence Project says Mack's is the longest wrongful conviction to be overturned on new DNA evidence that it knows of: 47 years.

Mack's case had the most common ingredient in the DNA exoneration record, an eyewitness who identified the wrong man. Here is what the numbers show about how wrongful convictions happen, who works to undo them, and how long it takes.

The Innocence Project

The Innocence Project was founded in 1992 by attorneys Barry Scheck and Peter Neufeld as part of a law clinic at the Benjamin N. Cardozo School of Law in New York. It started with cases where DNA testing could prove innocence and now also litigates cases built on other kinds of evidence. It says it has helped free more than 250 people.

No one knows how many innocent people are in prison. The Innocence Project cites studies estimating between 2.3 and 5 percent of U.S. prisoners. A 2014 study in the Proceedings of the National Academy of Sciences estimated that if everyone sentenced to death stayed under that sentence indefinitely, at least 4.1 percent would eventually be exonerated, and its authors called that a conservative estimate.

What 375 DNA exonerations show

The Innocence Project tracked every DNA exoneration in the United States from the first one, in 1989, until the count reached 375 in 2020. Those 375 people served an average of 14 years. Twenty-one had served time on death row. Forty-four had pleaded guilty to crimes they did not commit.

The causes repeat. Eyewitness misidentification was involved in 69 percent of the 375 cases. Misapplied forensic science was involved in 43 percent and false confessions in 29 percent. In 42 percent of the misidentification cases, the witness had identified someone of a different race.

The race of the people convicted is part of the record too. Of the 375, 225, or 60 percent, were African American, and 29, or 8 percent, were Latino.

DNA can also point toward someone else. As of August 2018, the Innocence Project counted 180 DNA exonerations, about half, in which the actual perpetrator had been identified.

The wider count

DNA cases are only part of the picture. The National Registry of Exonerations, now a project of the University of California, Irvine, counts exonerations based on any kind of new evidence. As of October 2026, its site lists 3,863 exonerations since 1989 and more than 36,191 years lost. Its annual report, published April 6, 2026, recorded 97 exonerations in 2025, the lowest yearly total in its annual reports since 2013. Official misconduct was present in at least 70 of them, and mistaken witness identification in 23 percent.

Eyewitnesses, confessions and informants

Eyewitness error leads the DNA cases because a confident witness is persuasive and memory is not a recording. In Mack's case, the Innocence Project describes the identification procedures as highly suggestive. False confessions and jailhouse informants are the other recurring problems. Informants are often offered something in return for testimony, such as a lighter sentence, which gives them a reason to say what investigators want to hear.

Evidence that was withheld

Government misconduct includes failing to turn over evidence favorable to the defense, which prosecutors are required to disclose. Michael Morton was convicted in Texas in 1987 of murdering his wife and spent nearly 25 years in prison before DNA testing cleared him. He was released on October 4, 2011, and officially exonerated on December 19, 2011. His trial prosecutor, Ken Anderson, faced proceedings over evidence that had not been disclosed. In November 2013, Anderson entered a plea to criminal contempt, agreed to serve a 10-day jail sentence, resigned as a district judge and permanently surrendered his law license.

Ryan Ferguson was convicted in 2005 in the 2001 killing of Kent Heitholt, a sports editor at the Columbia Daily Tribune in Missouri. Both witnesses against him later recanted. On November 5, 2013, the Missouri Court of Appeals vacated his conviction, ruling that prosecutors had failed to disclose evidence showing that a key witness had lied at trial. The state declined to retry him, and he was released that month. His lawyer was Kathleen Zellner.

The Innocence Network

The New York organization is one member of the Innocence Network, a coalition of independent groups that provide free legal and investigative help to people trying to prove their innocence. The Indiana Innocence Project became the network's 74th member in September 2025. The network's members operate across the United States and in a dozen other countries, and say they have collectively exonerated more than 850 people since 2005.

Some exonerees go on to do the work themselves. Jarrett Adams was convicted of sexual assault in Wisconsin at 17 and sentenced to 28 years. With the Wisconsin Innocence Project's help, he won a unanimous reversal from the federal Seventh Circuit Court of Appeals on June 30, 2006, on the ground that his trial lawyer had been ineffective. The charges were dismissed in 2007. He graduated from Loyola University Chicago School of Law in 2015 and in 2016 became the first exoneree hired as a staff attorney by the Innocence Project.

Decades lost

Glenn Ford, a Black man, was sentenced to death by an all-white jury in Shreveport, Louisiana, for the 1983 killing of a jeweler. His court-appointed lead lawyer had never tried a case to a jury. He spent about 30 years on death row at Angola before his release on March 10, 2014, after the state revealed it had information, never disclosed to the defense, that another man originally charged in the case had confessed.

Archie Williams was convicted in Louisiana in 1983 of attempted murder, aggravated rape and aggravated battery and sentenced to life without parole. DNA testing the Innocence Project won in 2007 did not clear him. A fingerprint did. In March 2019, unidentified prints from the victim's bedroom were run through the FBI's Next Generation Identification system, and examiners concluded some of them belonged to a man who had pleaded guilty to other sexual assaults in the same neighborhood and died in prison in 1996. He was never questioned about this attack. Williams's convictions were vacated on March 21, 2019, 36 years after his arrest.

Perry Lott was convicted in Oklahoma in 1988 of rape, burglary and other charges and sentenced to 350 years. DNA testing sought by the Innocence Project in 2017 found two male profiles, neither his. He was released in July 2018 after more than 30 years, under a deal that required him to drop his challenge, and on October 10, 2023, a judge vacated his convictions and dismissed the case. Anthony Wright was convicted in Philadelphia in 1993 of a 1991 rape and murder, and avoided a death sentence by a 7-to-5 jury vote. DNA testing pointed to another man, and in August 2016 a jury acquitted Wright at a retrial after he had served 25 years.

Several of these cases turned on evidence that had been sitting in a police file, a lab freezer or a fingerprint card for years. The record does not show that the system usually gets it wrong. It shows that when it does, the mistake is hard to find and slow to fix.

Sources

1. Hit in DNA database proves Leonard Mack's innocence after 47 years of wrongful conviction (Innocence Project)
2. About the Innocence Project (FAQ: founding, estimates of innocent prisoners)
3. DNA Exonerations in the United States (1989-2020) (Innocence Project)
4. 2025 Annual Report (National Registry of Exonerations, April 6, 2026)
5. Ryan Ferguson (National Registry of Exonerations)
6. Rate of false conviction of criminal defendants who are sentenced to death (Gross et al., PNAS, 2014)
7. Michael Morton (Innocence Project case page)
8. Archie Williams (Innocence Project case page)
9. Glenn Ford Is Exonerated and Released After 30 Years on Louisiana's Death Row (Equal Justice Initiative)
10. Indiana Innocence Project accepted into global anti-wrongful conviction network (WFYI/IPM, September 9, 2025)
11. Jarrett M. Adams (Wikipedia)

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