The Nail Collector

HOW DO YOU CATCH A KILLER ALREADY BEHIND BARS?

A woman lies dead in the green grass of the Common. A woman Detective Arla Baker used to know....
The finger points to a sadistic maniac from many years ago. A killer that Arla Baker put behind bars. He swore revenge back then.
As women around Arla begin to die, she knows time is running out. She has to act soon, to stop the past from destroying her life. Because this time, it seems the killer is back for her.
But there's one puzzle she can't solve. How can she get to a criminal who's already in prison?