Derrick Hamilton, center, walks among a group of men wearing caps reading "wrongfully convicted," after he was exonerated on Friday, Jan. 9, 2015, in New York. Hamilton's 1991 murder conviction was vacated after prosecutors told a New York City judge that the state's key witness had lied about who did it. The decision at the hearing cleared Hamilton, who had served 21 years in prison before being paroled in 2011. (AP Photo/Bebeto Matthews), APTOPIX