Cooper said they had and proceeded to test several of them.

He read the computer screen. “No cotton and no soda, sulfite, or sulfate.”

These were chemicals added to the pulping process in making high-quality paper.

“It’s cheap paper. And the dye’s water soluble. There’s no oil-based ink.”

“So,” Rhyme announced, “it’s not money.”

“Probably recycled,” Cooper said.

Rhyme magnified the screen again. The matrix was large now and the detail lost. He was momentarily frustrated and wished that he was looking through a real compound ’scope eyepiece. There was nothing like the clarity of fine optics.

Then he saw something.

“Those yellow blotches, Mel? Glue?”

The tech looked through the microscope’s eyepiece and announced, “Yes. Envelope glue, looks like.”

So possibly the key had been delivered to the Dancer in an envelope. But what did the green paper signify? Rhyme had no idea.

Sellitto folded up his phone. “I talked to Ron Talbot at Hudson Air. He made a few calls. Guess who leases that hangar where the Dancer waited.”

“Phillip Hansen,” Rhyme said.

“Yep.”

“We’re making a good case,” Sachs said.

True, Rhyme thought, though his goal was not to hand the Dancer over to the AG with a watertight case. No, he wanted the man’s head on a pike.

“Anything else there?”

“Nothing.”

“Okay, let’s move on to the other scene. The sniper’s nest. He was under a lot of pressure there. Maybe he got careless.”

But, of course, he hadn’t been careless.

There were no shell casings.

“Here’s why,” Cooper said, examining the trace through the ’scope. “Cotton fibers. He used a dish towel to catch the casings.”

Rhyme nodded. “Footprints?”

“Nope.” Sachs explained that the Dancer’d worked his way around the patches of exposed mud, staying on the grass even when he was racing to the catering van to escape.

“How many FRs you find?”

“None at the sniper’s nest,” she explained. “Close to two hundred in the two vans.”

Using AFIS—the automated fingerprint identification system that linked digitalized criminal, military, and civil service fingerprint databases around the country—a cold search of this many prints would be possible (though very time consuming). But as obsessed as Rhyme was with finding the Dancer, he didn’t bother with an AFIS request. Sachs reported that she’d found his glove prints in the vans too. The friction ridge prints inside the vehicles wouldn’t be the Dancer’s.

Cooper emptied the plastic bag onto an examining tray. He and Sachs looked over it. “Dirt, grass, pebbles . . . Here we go. Can you see this, Lincoln?” Cooper mounted another slide.

“Hairs,” Cooper said, bent over his own ’scope. “Three, four, six, nine . . . a dozen of ’em. It looks like a continuous medulla.”

The medulla is a canal running through the middle of a strand of some types of hair. In humans, the medulla is either nonexistent or fragmented. A continuous medulla meant the hair was animal. “What do you think, Mel?”

“I’ll run them through the SEM.” The scanning electron microscope. Cooper ran the scale up to 1500X magnification and adjusted dials until one of the hairs was centered in the screen. It was a whitish stalk with sharp-edged scales resembling a pineapple’s skin.