"He must be wearing some kind of glove," Cooper said, "with fake friction ridges on them. Never seen that before."
Who the hell was this perp?
The results from the chromatograph/spectrometer popped onto a computer screen. "Okay, I've got pure latex . . . and what's this?" he pondered. "Something the computer identifies as an alginate. Never heard of--"
"Teeth."
"What?" Cooper asked Rhyme.
"It's a powder you mix with water to make molds. Dentists use it for crowns and dental work. Maybe our doer'd just been to the dentist."
Cooper continued to examine the computer screen. "Then we have very minute traces of castor oil, propylene glycol, cetyl alcohol, mica, iron oxide, titanium dioxide, coal tar and some neutral pigments."
"Some of those're found in makeup," Rhyme said, recalling a case in which he'd placed a killer at the scene after the man wrote obscene messages on the victim's mirror with a touch-up stick, smears of which were found on his sleeve. Running the case, he'd made a study of cosmetics.
"Hers?" Cooper asked Sachs.
"No," the policewoman answered. "I took swabs of her skin. She wasn't wearing any."
"Well, put it on the board. We'll see if it means anything."
Turning to the rope, the murder weapon, Mel Cooper looked up from his slump over a porcelain examining board. "It's a white sheath of rope around a black core. They're both braided silk--real light and thin--which is why it doesn't look any thicker than a normal rope even though it's really two put together."
"What's the point of that? Does the core make it stronger?" Rhyme asked. "Easier to untie? Harder to untie? What?"
"No idea."
"It's getting mysteriouser," Sachs said with a dramatic flair that Rhyme would have found irritating if he hadn't agreed with her.
"Yup," he confirmed, disconcerted. "That's a new one to me. Let's keep going. I want something familiar, something we can use."
"And the knot?"
"Tied by an expert but I don't recognize it," Cooper said.
"Get a picture of it to the bureau. And . . . don't we know somebody at the Maritime Museum?"
"They've helped us with knots a few times," Sachs said. "I'll upload a picture to them too."
A call came in from Tobe Geller at the Computer Crimes Unit at New York's FBI headquarters. "This is fun, Lincoln."
"Glad we're keeping you amused," Rhyme murmured. "Anything helpful you might be able to tell us about our toy?"
Geller, a curly-haired young man, was impervious to Rhyme's edge, especially since there was a computer product involved. "It's a digital audio recorder. Fascinating little thing. Your unsub recorded something on it, stored the sounds on a hard drive then programmed it to play back after some delay. We don't know what the sound was--he built in a wiping program so that it destroyed the data."
"It was his voice," Rhyme muttered. "When he said he had a hostage it was just a recording. Like the chairs. It was to make us think he was still in the room."
"That makes sense. It had a special speaker--small but excellent bass and midtone range. It'd mimic a human voice pretty well."
"There's nothing left on the disk?"
"Nope. Gone for good."
"Damn. I wanted a voiceprint."
"Sorry. It's gone."
Rhyme sighed in frustration and rolled back to the examination trays; it was left to Sachs to tell Geller how much they appreciated the help.