Lonely Hearts. Natalie Dvorak Mysteries, #22

Natalie Dvorak #22:Detective-Sergeant Natalie Dvorak has a new boss at the State Police barracks. He's young, enthusiastic, and a nuisance to the established team of investigators. Natalie's colleagues Sharon Fallon and Harry Wainwright are already working the case of a man who finds his victims in the local paper's personal ads. Sharon meets the physical type and becomes the bait when the police place their own ad.
The potential physical danger for Sharon is complicated by personal feelings after a breakup with Sharon's own fiancé. Meanwhile, a snitch tips the lieutenant about a drug buy going down and Natalie joins the operation against a father and son criminal team. But it all goes wrong and a police mistake touches off a bloody multiple homicide. Natalie is sure she knows who the killers are but can she prove it?