The Deliveryman (Lincoln Rhyme 11.50)

"I was thinking. Locard was talking about 'material' or 'dust'?" A glance toward Juliette in the front row, center. An attractive woman, long hair, straight and the color of polished mahogany.

"Correct."

"Couldn't there also be a psychological transference?"

"How do you mean?"

"Say the perp threatens to torture the victim before he kills him. The victim has a look of terror on his face. We can infer that the perp was a sadist. Add that to the psychological profile. Maybe narrow down the field of suspects."

Proper use of infer, Rhyme noted. Often confused with the transitive imply. He said, "A question. Did you enjoy that series of books? Harry Potter? Movies too, right?" As a rule, cultural phenomena didn't interest him much--not unless they might help solve a crime, which happened, more or less, never. But Potter was, after all, Potter.

The young man squinted his dark eyes. "Yeah, sure."

"You do know that it was fiction, right? That Hogworths doesn't exist?"

"Hogwarts. And I'm pretty aware of that, yes."

"And you concur that casting spells--like voodoo, ghosts, telekinesis and your theory of the transfer of psychological elements at crime scenes--"

"Are hogwash, you're saying?"

Drawing laughs.

Rhyme's brows veed, though not at the interruption; he liked insolence (and in fact the pun was rather clever). It was a substantive complaint. "Not at all. I was going to say that all of those theories have yet to be empirically proven. You present me with objective studies repeatedly duplicating incidents of your purported psychological transference, including a valid sampling size and controls, and I'll consider the question. I myself wouldn't use it. Focusing on more subjective aspects of an investigation distracts from the important task at hand. Which is?"

"The evidence." Juliette Archer again.

"Crime scenes change like a dandelion under a sudden breath. Those three ligands started out as a million only a minute earlier. A drop of rain can wash away a speck of the killer's DNA, which happens to be in the CODIS database, identifying him by address, phone number, social and shirt size." A look over the room. "Shirt size was a joke." People tended to believe everything that Lincoln Rhyme said.

The hipster cop nodded, unconvinced. Rhyme was impressed. He wondered if the student would in fact look into the subject. There might actually be something to it.

"We'll speak more about Monsieur Locard's dust--that is, trace evidence--in a few weeks. Today our subject will be making sure that we have dust to analyze. Preserving the crime scene. You will never have a virgin crime scene. That does not exist. Your job will be to make sure your scenes are the least contaminated they can be. Now, what is the number one contaminant?" Without waiting for a response he said, "Yes, fellow cops, often the brass. How we control that...and still keep our jobs?"

The laughter died down and Rhyme began his lecture.

An hour later he noted the time and dismissed the class. He wheeled to the ramp that led off the low stage (the school was totally compliant with the Americans with Disabilities Act, and then some).

All the students filed out, except one.

Juliette Archer, whom he estimated to be in her mid-thirties, about ten years younger than he, was still in the first row. Her eyes were quite remarkable, Rhyme had noted when he'd seen her for the first time, in class last week. There are no blue pigments in human iris or aqueous humor; that shade comes from the amount of melanin in the iris pigment epithelium, combined with the Rayleigh scattering effect. Archer's were rich cerulean.

He wheeled up to her. "Locard. You did some supplemental reading. My book. That was the language you paraphrased." He hadn't assigned his own textbook to the class.

"Needed some reading material to go with my wine and dinner the other day."

"Ah."

She said, "Well?"

Nothing more by way of explanation was necessary.

Her eyes remained steadily on his. "I'm just not sure it would be that good an idea."

"Not a good idea?"

"Not helpful, I mean. For you."

"I disagree."