Say Goodbye (FBI Profiler #6) by Lisa Gardner

If he's coming for you, there's no chance to say goodbye . . .

Young women are disappearing. Girls no one will notice are gone: prostitutes, runaways, high-risk teens. One night they exist, next morning they've vanished.

But FBI Special Agent Kimberly Quincy has noticed. And when eighteen-year-old Delilah Rose claims to have inside information on the case, she will only talk to Kimberly. After all, they have something in common: they are both pregnant.

Their only lead is a man who gets his kicks in the creepiest of ways. And as she hunts a twisted sadist with a brutal past, Kimberly soon realises there's only one way to halt the bloody killings. She must become the prey.