I agree that his crime was disgusting, and that he should have taken his punishment back in the 1970s, but in this case, the U.S refused to provide the Swiss with information they needed to fully justify the extradition (namely, the testimony of the prosecutor that Polanski's legal team accused of impropriety). Perhaps there is something in the prosecutor's old statements that support Polanski's claims and might prove embarrassing to the U.S judicial system if it were released. In any event, if the U.S wanted Polanski so badly, it should have given all of the relevant documents. Its failure to do so makes one wonder if the U.S really wants him back after all.
One student killed, three wounded at Arizona campus during fight (a)
from the article: Switzerland decides not to extradite Roman Polanski to U.S.