Let the Devil Sleep by John Verdon

The most decorated homicide detective in NYPD history, Dave Gurney is still trying to adjust to his life of quasi-retirement in upstate New York when a young woman who is producing a documentary on a notorious murder spree seeks his counsel. Soon after, Gurney begins feeling threatened: a razor-sharp hunting arrow lands in his yard, and he narrowly escapes serious injury in a booby-trapped basement. As things grow more bizarre, he finds himself reexamining the case of The Good Shepherd. Mocked even by some who'd been his supporters, Dave realizes the killer is too clever to ever be found. The only gambit that may make sense is also the most dangerous - to make himself a target and get the killer to come to him.