Corrupted, by Lise Scottoline

Bennie Rosato is asked by a former client to defend him on a murder charge.  Because she feels that she let him down when he was put in juvenile hall by a corrupt judge, Bennie agrees to defend him. Because she got involved at the time with the uncle of the murdered man, Bennie plays it all very close to the vest. She figures it out, of course.  Pretty weak and improbable.