Innocence After Guilt Episode 1: An Introduction to Post-Conviction DNA Testing – ISHI News

Jun 29 2023

Innocence After Guilt Episode 1: An Introduction to Post-Conviction DNA Testing


According to the National Registry of Exonerations, there have been 3,337 exonerations since 1989 accounting for more than 29,500 years lost. In our quest for justice, how do we work to eliminate wrongful convictions? What has history taught us? What role has forensic DNA played since its emergence? In this video series we delve into the role of DNA testing in the United States in post-conviction work to exonerate the innocent and reassert convictions of the guilty.


In this series, we meet John Collins (an authoritative leadership and expertise coach in forensic science), Tiffany Roy (a forensic DNA expert), Michael Ware (Executive Director for the Innocence Project of Texas), and Peter Valentin (Chair of the Forensic Science Department at the University of New Haven).


They delve into the role and importance of post-conviction DNA testing and why it should be embraced by those in the justice system instead of avoided by sharing their own experiences on working post-conviction cases.





One such case is that of Johnny Pinchback, who was sentenced to life in prison for an aggravated sexual assault that he did not commit. After 27 years, he was exonerated thanks to the Innocence Project of Texas.


On March 22, 1984, two teenage girls were confronted by a man with a gun as they walked along Illinois Avenue in Dallas. The man took them to a nearby vacant lot where he sexually assaulted them. The man fled on foot and the victims went to a nearby home and called police.


A few days later, the two were at the apartment where one of them lived when they noticed a man in the parking lot who they believed was the man who attacked them. They recorded the license plate number of the man’s car and called the police.


Police spoke with the owner of the vehicle who said he had loaned the car to 28-year-old Johnny Pinchback. When Johnny learned that the police were looking for him, he went to authorities. After briefly questioning him, Johnny was released. On April 4, police presented a photo line-up to the two girls, who both identified Johnny as their attacker.


On October 5, 1984, Johnny was convicted based almost solely on the identifications of the victims. He was found guilty of two counts of aggravated sexual assault and was sentenced to 99 years in prison.


After his conviction, Johnny learned the name of a man that his friends claimed had confessed to committing the sexual assaults. A motion for a new trial was filed based on newly discovered evidence but was rejected. Johnny lost his appeals and in October 2007 wrote a letter to the Innocence Project of Texas (IPTX). In May 2009, IPTX launched an investigation of his case.


On July 13, 2010, the Dallas County District Attorney’s Office joined with IPTX to request DNA tests of remaining physical evidence. The testing found a small amount of seminal fluid and isolated a male DNA profile from the fluid that was different from Johnny’s, proving that he was not the rapist. On May 12, 2011, Johnny was released from prison.


Today, Johnny is a board member for the Innocence Project of Texas, helping others who have been wrongfully convicted. The science that was used to retest evidence in his case did not exist in 1984, underscoring the importance of post-conviction DNA testing and those who perform this work.


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