Death row inmate Damon Thibodeaux walked free after 15 years behind bars after DNA evidence showed he had been wrongfully convicted of the rape and murder of his cousin, authorities said.

The 38-year-old was released from the Louisiana State Penitentiary in the early afternoon on Friday, Pam Laborde, communications director for the Louisiana Department of Public Safety and Corrections told AFP.

Thibodeaux is the 18th death row inmate released due to DNA evidence in the United States, according to the Death Penalty Information Center (DPIC). The first was Kirk Bloodsworth, who was freed in 1993 after being wrongfully convicted of the rape and murder of a nine-year-old girl.

"It takes a long time to find these cases," DPIC executive director Richard Dieter told AFP.

"If executions are rushed and accelerated then we are going to miss these cases," he added. "It underscores the fundamental problems that the death penalty could actually kill innocent people."

According to the Innocence Project, Thibodeaux is the 300th person to be exonerated of a wrongful conviction by DNA evidence in the United States.

Thibodeaux started his time on death row on October 24, 1997 for the rape and murder a year earlier of his 14-year-old cousin. His execution date had not been set, according to Laborde.

His conviction and death sentence was based solely on a confession made after a nine-hour interrogation that was proven wrong after a investigation involving DNA, forensic evidence, and a number of interviews, the American Civil Liberties Union, said in a statement.

Since 2000, six people have been exonerated from Louisiana's death row, compared to three executions, according to the ACLU.

"The people of Louisiana should demand a moratorium on executions until they can be assured there are no more miscarriages of justice like the one that occurred in this case," Denise LeBoeuf, director of the ACLU Capital Punishment Project, who has represented Thibodeaux since 1998, said in the statement.

"Hopefully this case can serve as a model to other district attorneys around the country who are interested in developing conviction integrity units to review old cases," added Barry Scheck, co-director of the Innocence Project, in the same statement.