The Vanished Man

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 ahorse 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,