“First, I’ll take a baseline reading of the witness—see how he acts when he’s answering things that we know are truthful—name, address, job, things like that. I’ll note his gesturing, posture, word choice and the substance of what he says.

“Once I have the baseline I’ll start asking questions and find out where he exhibits stress reactions. Which means he’s either lying or has some important issues with the topic I’m asking him about. Up until then, what I’ve been doing is ‘interviewing’ him. Once I suspect he’s lying, then the session will become an ‘interrogation.’ I start to whittle away at him, using a lot of different techniques, until we get to the truth.”

“Perfect,” said Baker. Although Rhyme was apparently in charge, Dennis Baker, Dance deduced, was from headquarters; he had the belabored look of a man on whose shoulders an investigation like this ultimately—and politically—rested.

“You have a map of the area we’re talking about,” Dance said. “I’d like to know the geography of the area involved. You can’t be an effective interrogator without it. I like to say I need to know the subject’s terrarium.”

Lon Sellitto gave a fast laugh. Dance smiled in curiosity. He explained, “Lincoln says exactly the same about forensics. If you don’t know the geography, you’re working in a vacuum. Right, Linc?”

“Sorry?” the criminalist asked.

“Terrarium, you like that?”

“Ah.” His polite smile was the equivalent of Dance’s son saying, “Whatever.”

Dance examined the map of lower Manhattan, memorizing the details of the crime scene and of Ari Cobb’s afterwork schedule the previous day, as Sachs and a young patrol officer, named Pulaski, pointed them out.

Finally she felt comfortable with the facts. “Okay, let’s get to work. Where is he?”

“A room across the hall.”

“Bring him in.”

Chapter 7

A moment later an NYPD patrol officer brought in a short, trim businessman wearing an expensive suit. Dance didn’t know if they’d actually arrested him but the way he touched his wrists told her that he’d been in cuffs recently.

Dance greeted the man, who was uneasy and angry, and nodded him to a chair. She sat across from him—nothing between them—and scooted forward until she was in a neutral proxemic zone, the term referring to the physical space between a subject and an interviewer. This zone can be adjusted to make the subject more or less comfortable. She was not too close to be invasive but not so far away as to give him a sense of security. (“You push the edge of edgy,” she’d say in her lectures.)

“Mr. Cobb, my name’s Kathryn Dance. I’m a law enforcement agent and I’d like to talk to you about what you saw last night.”

“This is ridiculous. I already told them”—a nod at Rhyme—“everything I saw.”

“Well, I just arrived. I don’t have the benefit of your previous answers.”

Jotting responses, she asked a number of simple questions—where he lived and worked, marital status, and the like—which gave her Cobb’s baseline reaction to stress. She listened carefully to his answers. (“Watching and listening are the two most important parts of the interview. Speaking comes last.”)