As the aide did, Rhyme blurted, "Thom, we're going to deputize you. Give him a shiny badge or something, Lon."
"Lincoln," he muttered.
"We need you. Come on. Haven't you always wanted to be Sam Spade or Kojak?"
"Only Judy Garland," the aide replied.
"Jessica Fletcher then! You'll be writing the profile. Come on now, get out that Mont Blanc you're always letting stick vainly out of your shirt pocket."
The young man rolled his eyes as he lifted his Parker pen and took a dusty yellow pad from a stack under one of the tables.
"No, I've got a better idea," Rhyme announced. "Put up one of those posters. Those art posters. Tape it up backwards and write on the back in marker. Write big now. So I can see it."
Thom selected a Monet lily pads and mounted it to the wall.
"On the top," the criminalist ordered, "write 'Unsub 823.' Then four columns. 'Appearance. Residence. Vehicle. Other.' Beautiful. Now, let's start. What do we know about him?"
Sellitto said, "Vehicle . . . He's got a Yellow Cab."
"Right. And under 'Other' add that he knows CS--crime scene--procedures."
"Which," Sellitto added, "maybe means he's had his turn in the barrel."
"How's that?" Thom asked.
"He might have a record," the detective explained.
Banks said, "Should we add that he's armed with a .32 Colt?"
"Fuck yes," his boss confirmed.
Rhyme contributed, "And he knows FRs. . . ."
"What?" Thom asked.
"Friction ridges--fingerprints. That's what they are, you know, ridges on our hands and feet to give us traction. And put down that he's probably working out of a safe house. Good job, Thom. Look at him. He's a born law enforcer."
Thom glowered and stepped away from the wall, brushing at his shirt, which had picked up a stringy cobweb from the wall.
"There we go, folks," Sellitto said. "Our first look at Mr. 823."
Rhyme turned to Mel Cooper. "Now, the sand. What can we tell about it?"
Cooper lifted the goggles onto his pale forehead. He poured a sample onto a slide and slipped it under the polarized-light 'scope. He adjusted dials.
"Hmm. This is curious. No birefringence."
Polarizing microscopes show birefringence--the double refraction of crystals and fibers and some other materials. Seashore sand birefringes dramatically.
"So it isn't sand," Rhyme muttered. "It's something ground up. . . . Can you individuate it?"
Individuation . . . The goal of the criminalist. Most physical evidence can be identified. But even if you know what it is there are usually hundreds or thousands of sources it might have come from. Individuated evidence is something that could have come from only one source or a very limited number of sources. A fingerprint, a DNA profile, a paint chip that fits into a missing spot on the perp's car like a jigsaw-puzzle piece.
"Maybe," the tech responded, "if I can figure out what it is."
"Ground glass?" Rhyme suggested.
Glass is essentially melted sand but the glassmaking process alters the crystalline structure. You don't get birefringence with ground glass. Cooper examined the sample closely.