"Scope 'em."

The tech lifted them off with a pair of tweezers and mounted them on slides. He put them under the stereo-binocular microscope – the preferred instrument for analyzing fibers – and then hit a button. The image he was looking at through the eyepiece popped onto the large flat-screen computer monitor for everyone to see.

The fibers appeared as thick strands, grayish in color.

Fibers are important forensic clues because they're common, they virtually leap from one source to another and they can be easily classified. They fall into two categories: natural and man-made. Rhyme noted immediately that these weren't viscous rayon or polymer-based and therefore had to be natural.

"But what kind specifically?" Mel Cooper wondered aloud.

"Look at the cell structure. I'm betting it's excremental."

"Whatsat?" Sellitto asked. "Excrement? Like shit?"

"Excrement, like silk. It comes from the digestive tract of worms. Dyed gray. Processed to a matte finish. What's on the other slides, Mel?"

He ran these through the scope too and found they were identical fibers.

"Was the perp wearing gray?"

"No," Sellitto reported.

"The vic wasn't either," Sachs said.

More mysteries.

"Ah," Cooper said, peering into the eyepiece, "might have a hair here."

On the screen a long strand of brown hair came into focus.

"Human hair," Rhyme called out, noting hundreds of scales. An animal hair would have at most dozens. "But it's fake."

"Fake?" Sellitto asked.

"Well," he said impatiently, "it's real hair but it's from a wig. Obviously. Look – at the end. That's not a bulb. It's glue. Might not be his, of course, but it's worth putting on the chart."

"That he's not brown-haired?" Thom asked.

"The facts," Rhyme said tersely, "are all we care about. Write that the unsub is possibly wearing a brown wig."

"Okay, bwana."

Cooper continued his examination and found that two of the adhesive squares revealed a minuscule bit of dirt and some plant material.

"Scope the plant first, Mel."

In analyzing crime scenes in New York, Lincoln Rhyme had always placed great importance on geologic, plant and animal evidence because only one-eighth of the city is actually on the North American mainland; the rest is situated on islands. This means that minerals, flora and fauna tend to be more or less common to particular boroughs and even neighborhoods within them, making it easier to trace substances to specific locations.

A moment later a rather artistic image of a reddish twig and a bit of leaf appeared on the screen.

"Good," Rhyme announced.

"What's good about it?" Thom asked.

"It's good because it's rare. It's a red pignut hickory. You hardly ever find them in the city. The only place I know of are Central and Riverside Parks. And… oh, look at that. That little blue-green mass?"

"Where?" Sachs asked.

"Can't you see it? It's right there!" Feeling painfully frustrated that he couldn't leap from his chair and tap the screen. "Lower right-hand corner. If the twig's Italy then the mass is Sicily."

"Got it."

"What do you think, Mel? Lichen, right? And I'd vote for Parmelia conspersa."

"Could be," the tech said cautiously. "But there're a lot of lichens."

"But there aren't a lot of blue-green and gray lichens," Rhyme replied dryly. "In fact, hardly any. And this one is most abundant in Central Park… We've got two links to the park. Good. Now let's look at the dirt."

Cooper mounted another slide. The image in the microscope – grains of dirt like asteroids – wasn't forensically revealing and Rhyme said, "Run a sample through the GC/MS."

The gas chromatograph/mass spectrometer is a marriage of two chemical-analysis instruments, the first of which breaks down an unknown substance into its component parts with the second determining what each of those parts is. White powder that appears uniform, for instance, might be a dozen different chemicals: baking soda, arsenic, baby powder, phenol and cocaine. The chromatograph has been compared to a horse race: the substances start out moving through the instrument together but they progress at different rates, becoming separated. At the "finish line" the mass spectrometer compares each one with a huge database of known substances to identify it.

The results of Cooper's analysis showed that the dirt Sachs had recovered was impregnated with an oil. The database, though, reported only that it was mineral-based – not plant or animal – and couldn't identify it specifically.

Rhyme commanded, "Send it to the FBI. See if their lab people've run across it." Then he squinted into a plastic bag. "That's the black cloth you found?"

Might be a clue, might be nothing…

She nodded. "It was in the corner of the lobby where the victim was strangled."

"Was it hers?" Cooper wondered.

"Maybe," Rhyme said, "but for the time being let's go on the assumption it's the killer's."

Cooper carefully lifted out the material. He examined it. "Silk. Hemmed by hand."

Rhyme observed that even though it could be folded into a tiny wad it opened up to be quite large, about six-by-four feet.

"We know from the timing he was waiting for her in the lobby," Rhyme said. "I'll bet that's how he did it: hid in the corner with that cloth draped over him. He'd be invisible. He probably would've taken it with him except the officers showed up and he had to get away."

What the poor girl must've felt when the killer materialized as if by magic, cuffed her and strung the rope around her neck.

Cooper found several flecks adhering to the black cloth. He mounted them on a slide. An image soon popped up on the screen. Under magnification the flecks resembled ragged pieces of flesh-colored lettuce. He touched one with a fine probe. The material was springy.

"What the hell is that?" Sellitto asked.

Rhyme suggested, "Rubber of some kind. Shred of balloon – no, too thick for that. And look at the slide, Mel. Something smeared off. Flesh-colored too. Run it through the GC."

While they waited for the results the doorbell rang.

Thom stepped out of the room to open the door and returned with an envelope.

"Latents," he announced.

"Ah, good," Rhyme said. "Fingerprints are back. Run them through AFIS, Mel."

The powerful servers of the FBI's automated fingerprint identification system, located in West Virginia, would search digitized images of friction ridges – fingerprints – throughout the country and return the results in hours, possibly even minutes if the latents team had found good, clear prints.

"How do they look?" Rhyme asked.

"Pretty clean." Sachs held up the photos for him to see. Many were just partials. But they had a good print of his whole left hand. The first thing Rhyme noticed was that the killer had two deformed fingers on that hand – the ring and little fingers. They were joined, it seemed and ended in smooth skin, without prints. Rhyme had a working knowledge of forensic pathology but couldn't tell whether this was a congenital condition or the result of an injury.

Ironic, Rhyme thought, gazing at the picture, the unsub's left ring finger is damaged; mine is the only extremity below my neck that can move at all.

Then he frowned. "Hold off on the scan for a minute, Mel… Closer, Sachs. I want to see them closer."

She stepped next to Rhyme and he examined the prints again. "Notice anything unusual about them?"

She said, "Not really… Wait." She laughed. "They're the same." Flipping through the pictures. "All his fingers – they're the same. That little scar, it's in the same position on every one of them."

"He must be wearing some kind of glove," Cooper said, "with fake friction ridges on them. Never seen that before."