Read one of the cases of people on the Innocence Project web page who have been exonerated, each one of them was convicted and sentenced to prison. Since 1989 329 people have been exonerated by DNA evidence. As a result of these exonerations and media portrayals of them, nearly 40 states have changed their laws to allow for appellate or post-conviction review on the grounds of actual innocence.
Should there be judicial review of convictions on the basis of evidence that may exonerate someone?
https://www.innocenceproject.org/cases/