It ends with her
(Book)

FBI special agent Clarke Sinclair doesn't give up easily. She has spent years tracking serial killer Simon Cross, forced to follow his twisted clues and photographs across the country. Clarke knows that Cross selects only redheaded women and that he doesn't target another victim until Clarke discovers the previous one. He has never broken the pattern, until now. A girl has already gone missing in upstate New York when a second is kidnapped, a blond. The killer's MO has changed, sending Clarke back to the drawing board.