It's not like he's the only one. 208 people so far have been freed by DNA evidence by the Innocence Project.
"The Innocence Project was established in the wake of a landmark study by the United States Department of Justice and the United States Senate, in conjunction with Columbia Law School. Among the study's estimates are a 5% failure rate in the U.S. justice system, which suggests as many as 100,000 falsely convicted prisoners. Other reports place the estimate as high as 10%. 75% of wrongful convictions are caused by eyewitness misidentification."