A US man who served seven and a half years in prison for a rape he did not commit has been cleared nearly five decades later thanks to new DNA evidence, authorities said Tuesday.

Leonard Mack, now 72, was arrested in 1975, in Greenburgh, New York state, after the rape of a teenage girl, who had been walking home from school with another girl.

Police announced a search for a Black suspect in the mostly white neighborhood and shortly after picked up Mack, who is African American.

After a campaign by the Innocence Project, DNA evidence not available at the time has "conclusively excluded 72-year-old Mr Mack as the perpetrator and identified a convicted sex offender, who has now confessed to the rape," the Westchester County prosecutor's office said in a statement.

"This is the longest wrongful conviction in US history known to the Innocence Project to be overturned by DNA evidence," the district attorney's office said, citing Mack's "unwavering strength fighting to clear his name for almost 50 years."

According to the National Registry of Exonerations, 575 wrongly convicted people have been cleared based on new DNA tests since 1989 -- 35 of them while waiting for execution.

Researchers say that Black suspects are far more likely to be the subjects of wrongful convictions than innocent white people.

Although Black people account for only 13.6 percent of the total US population, more than half of the 3,300 people whose convictions were overturned between 1989 and 2022 were Black, the National Registry of Exonerations said.

Reacting to his exoneration, Mack said: "I am finally free."