“No.”

“No rumors? Nothing?”

“Don’t think so.”

“What about Joey?” I ask, referring to Sean’s partner, Detective Joey Guercio. “Has he blabbed to anybody?”

A millisecond’s hesitation. “No way. Look, just be cool like you always are. Except for last time. You feeling okay about that? Your nerves or whatever?”

I close my eyes. “I was until you asked.”

“Sorry. Just hurry down here. I’m going back in.”

A rush of anxiety blindsides me. “You can’t wait for me?”

“Probably better if I don’t.”

Better for you “¦”Fine.“

Focus on the case, I tell myself, checking the house numbers on Prytania to be sure where I am. They expect you to know your business.

The facts are simple enough. In the past thirty days, three men have been shot by the same gun, bitten by the same set of teeth, and-in two cases-marked by the saliva of a man whose DNA shows him 87 percent likely to be a Caucasian male. The NOPD crime lab did the ballistics that matched the bullets. The state police crime lab did the mitochondrial DNA match. And I matched the bite marks.

This is much more difficult than it appears to be on television. To explain my job to homicide detectives, I often tell them about the forensic researcher who used an articulated set of teeth to try to create perfectly matched bite marks on a corpse. He couldn’t do it. The lesson is clear, even to street cops. If matching two bite marks known to have come from the same set of teeth can be difficult, then matching marks that might have been made by any teeth among millions is next to impossible. Even comparing bite marks on a corpse with the teeth of a small group of suspects is more problematic than many odontologists pretend.

Saliva left in a bite mark by a killer can simplify things enormously, by providing DNA to compare against that of suspects.