A New Orleans man spent 36 years in prison for a 1986 rape he did not commit before he was finally released Thursday.

Sullivan Walter, 53, was exonerated Thursday, more than three-and-a-half decades since he was mistakenly identified as the perpetrator of a 1986 home invasion and rape, which occurred in a dark room, according to Innocence Project New Orleans (IPNO), a nonprofit that helps the wrongfully convicted.

"This is not just about individuals and their choices, but the systems that let them happen," Walter’s attorney, IPNO Legal Director Richard Davis, said in a Thursday statement posted to Facebook.

The nonprofit called Walter's conviction the "longest known wrongful incarceration of a juvenile in Louisiana history and the 5th in U.S. history."

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Sullivan Walter holds a shirt near Elayn Hunt Correctional Center in St. Gabriel, Louisiana

Sullivan Walter, 53, was wrongfully convicted of raping a woman in 1986 when he was 17 years old. (Travis Spradling/The Advocate)

The perpetrator of the 1986 rape was allegedly wearing a hat and face covering at the time of the crime, and the victim identified Walter, who was 17 at the time, seven weeks later, according to INPO. 

A serological test conducted in the 1980s did not identify Walter as the suspect in the case, but a jury convicted him, not knowing the results of the test, after a day-long trial. INPO, which brought the case forward to the Orleans Parish District Attorney’s Office Civil Rights Division, said Walter's trial attorney did not elicit the serological evidence from witnesses, "and the police officer analyst misrepresented the results of his testing."

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Judge Darryl Derbigny expressed anger that blood and semen evidence that could have cleared him never made it to the jury.

"To say this was unconscionable is an understatement," Derbigny told Walter, according to The Associated Press.

Walter's case could highlight more wrongful convictions, according to the nonprofit.

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A report attached to a request to vacate Walter's conviction states that there were "systematic deficiencies" in serological testing performed by the New Orleans Police Department and Coroner’s Office in the 1980s and early 1990s, prompting potential reviews "of every case in Orleans Parish in which ABO/secretor test findings and testimony may have figured in the conviction of a defendant," INPO said in its Facebook post.

Attorneys said the victim in the rape is now deceased. Emily Maw, an attorney with Williams’ office, said in court that authorities had reached out to the victim's son, who was not present, and that he had expressed regret on behalf of his mother about the wrongful conviction.

The Associated Press contributed to this report.