Finally he ordered that the sample be bombarded by the nit-yag, slang for a garnet laser that was state-of-the-art in raising otherwise invisible prints. Cooper was looking at the image under the ’scope while Rhyme examined it on his computer screen.

Rhyme gave a short laugh, squinted, then looked again, wondering if his eyes were playing tricks on him.

“Is that? . . . Look. Lower right-hand corner!” Rhyme called.

But Cooper and Sachs could see nothing.

His computer-enhanced image had found something that Cooper’s optical ’scope had missed. On the lip of metal that had protected the timer from being blown to smithereens was a faint crescent of ridge endings, crossings, and bifurcations. It was no more than a sixteenth of an inch wide and maybe a half inch long.

“It’s a print,” Rhyme said.

“Not enough to compare,” Cooper said, gazing at Rhyme’s screen.

There are a total of about 150 individual ridge characteristics in a single fingerprint but an expert can determine a match with only eight to sixteen ridge matches. Unfortunately this sample didn’t even provide half that.

Still, Rhyme was excited. The criminalist who couldn’t twist the focus knob of a compound ’scope had found something that the others hadn’t. Something he probably would have missed if he’d been “normal.”

He ordered the computer to load a screen capture program and he saved the print as a .bmp file, not compressing it to .jpg, to avoid any risk of corrupting the image. He printed out a hard copy on his laser printer and had Thom tape it up next to the crash-site-scene evidence board.

The phone rang and, with his new system, Rhyme tidily answered the call and turned on the speakerphone.

It was the Twins.

Also known by the affectionate handle “the Hardy Boys,” this pair of Homicide detectives worked out of the Big Building, One Police Plaza. They were interrogators and canvassers—the cops who interview residents, bystanders, and witnesses after a crime—and these two were considered the best in the city. Even Lincoln Rhyme, with his distrust of the powers of human observation and recall, respected them.

Despite their delivery.

“Hey, Detective. Hey, Lincoln,” said one of them. Their names were Bedding and Saul. In person, you could hardly tell them apart. Over the phone, Rhyme didn’t even try.

“What’ve you got?” he asked. “Find the cat lady?”

“This one was easy. Seven veterinarians, two boarding services—”

“Made sense to hit them too. And—”

“We did three pet-walking companies too. Even though—”

“Who walks cats, right? But they also feed and water and change the litter when you’re away. Figured it couldn’t hurt.”

“Three of the vets had a maybe, but they weren’t sure. They were pretty big operations.”

“Lotsa animals on the Upper East Side. You’d be surprised. Maybe you wouldn’t.”

“And so we had to call employees at home. You know, doctors, assistants, washers—”

“That’s a job. Pet washer. Anyway, a receptionist at a vet on Eighty-second was thinking it might be this customer Sheila Horowitz. She’s mid-thirties, short dark hair, heavyset. Has three cats. One black and the other blond. They don’t know the color on the third one. She lives on Lexington between Seventy-eighth and Seventy-ninth.”