Former Inmate Glenn Ford
Glenn Ford was imprisoned for 30 years, for something he did not do. Youtube

A US man who was freed last year after three decades on death row for a crime he did not commit has died of cancer.

Glenn Ford, from Shreveport, Louisiana, died in New Orleans aged 65, his lawyer said. He was diagnosed with lung cancer shortly after leaving the Angola State Penitentiary in March last year.

Supporters told he died "surrounded by friends, loved ones and family in recent days".

Hours after his passing, his case was cited by a Supreme Court judge in a dissenting opinion urging caution when handing death sentences.

"In Glenn Ford's case, the prosecutor admitted that he was partly responsible for Ford's wrongful conviction, issuing a public apology to Ford and explaining that, at the time of his conviction, he was 'not as interested in justice as [he] was in winning'," justice Steven Breyer wrote, The Guardian reported.

"To some degree, it must be because the law that governs capital cases is more complex. To some degree, it must reflect the fact that courts scrutinize capi­tal cases more closely. But, to some degree, it likely also reflects a greater likelihood of an initial wrongful convic­tion."

Sentenced to death in 1983 over the killing 56-year-old jeweller Isadore Rozeman, Ford always maintained his innocence.

He was eventually proved right and released after clocking the undesirable record of longest-serving death row inmate in the US.

The decision came as the state prosecutor said Louisiana could no longer stand by the conviction after new information supporting his innocence had come to light.