Here's a list of more than 150 men and women who were sentenced to death and exonerated before their date of execution since 1973. Innocence: List of Those Freed From Death Row | Death Penalty Information CenterIf you click on their names you can read about their cases.

So roughly, for every 10 people put to death in the last 40 or so years, one was later found to be unjustly sentenced.