Pulaski gave a laugh. "You know that, Lincoln? Where'd you learn about wires?"

"It's printed on the side, Rookie."

"Oh. I didn't notice."

"Obviously. And our perp cut it to this length, Mel. What do you think? Not machine cut."

"I'd agree." Using a magnifying glass, Cooper was examining the end of the metal cable that had been bolted to the substation wire. He then focused the video on the cut ends. "Amelia?"

Their resident mechanic looked it over. "Hand hacksaw," she offered.

The split bolts were unique to the power industry, it turned out, but they could have come from dozens of sources.

The bolts affixing the wire to the bus bar were similarly generic.

"Let's get our charts going," Rhyme then said.

Pulaski wheeled several whiteboards forward from the corner of the lab. On the top of one Sachs wrote, Crime Scene: Algonquin Substation Manhattan-10, West 57th Street. On the other was UNSUB Profile. She filled in what they'd discovered so far.

"Did he get the wire at the substation?" Rhyme asked.

"No. There wasn't any stored there," the young man said.

"Then find out where he did get it. Call Bennington."

"Right."

"Okay," Rhyme continued. "We've got metalwork and hardware. That means tool marks. The hacksaw. Let's look at the wire closely."

Cooper switched to a large-object microscope, also plugged into the computer, and examined where the wire had been cut; he used low magnification. "It's a new saw blade, sharp."

Rhyme gave an envious glance toward the tech's deft hands, moving the focus and the geared stage of the 'scope. Then he returned to the screen. "New, yes, but there's a broken tooth."

"Near the handle."

"Right." Before people began to saw, they generally rested the blade on what they were about to cut, three or four times. Doing this, especially in soft aluminum like the wire, could reveal broken or bent saw teeth, or other unique patterns that could link tools found in the perp's possession to the one used in a crime.

"Now, the split bolts?"

Cooper found distinctive scratch marks on all the bolts, suggesting that the perp's wrench had probably left them.

"Love soft brass," Rhyme muttered. "Just love it… So he's got well-used tools. More and more, looking like he's an insider."

Sellitto disconnected his call. "Nothing. Maybe somebody saw somebody in a blue jumpsuit. But it might've been an hour after it happened. When the whole friggin' block was crawling with Algonquin repair crews wearing friggin' blue jumpsuits."

"What've you found out, Rookie?" Rhyme barked. "I want sources for the wire."

"I'm on hold."

"Tell 'em you're a cop."

"I did."

"Tell 'em you're the chief cop. The big cheese."

But Rhyme's attention was already on something else: the iron bars forming the grate that barred entrance to the access tunnel.

"How he'd cut through them, Mel?"

A careful look revealed he hadn't used a hacksaw but a bolt cutter.

Cooper examined the ends of the bars through a microscope fitted with a digital camera and took pictures. He then transferred the shots to the central computer and assembled them onto one screen.

"Any distinctive marks?" Rhyme asked. As with the broken hacksaw tooth and scratches on the bolts and nuts, any unusual marking on the cutter would link its owner to the crime scene.

"How's that one?" Cooper asked, pointing at the screen.

There was a tiny crescent of scratch in roughly the same position on the cut surfaces of several of the bars. "That'll do. Good."

Then Pulaski cocked his head and readied his pen as somebody at Bennington Wire picked up the phone to speak to the young cop in his new capacity as the emperor of the New York City Police Department.

After a brief conversation he hung up.

"What the hell's with the cable, Pulaski?"

"First of all, that model cable's real common. They-"

"How common?"

"They sell millions of feet of it every year. It's mostly for medium-voltage distribution."

"Sixty thousand volts is medium?"

"I guess so. You can buy it from any electrical supply wholesaler. But he did say that Algonquin buys it in bulk."

Sellitto asked, "Who there would order it?"

"Technical Supplies Department."

"I'll give 'em a call," Sellitto said. He did so and had a brief conversation. He disconnected. "They're going to check to see if anything's missing from inventory."

Rhyme was gazing at the grating. "So he climbed through the manhole earlier and into the Algonquin work space under the alley."

Sachs said, "He might've been down the steam pipe manhole to do some work and seen the grating that led to the tunnel."

"Definitely suggests it's an employee." Rhyme hoped this was the case. Inside jobs made cops' work a lot easier. "Let's keep going. The boots."

She said, "Similar boot prints in both the access tunnel and near where the wire was rigged inside the substation."

"And any prints from the coffee shop?"

"That one," Pulaski responded, as he pointed to an electrostatic print. "Under the table. Looks like the same brand to me."

Mel Cooper examined it and concurred. The young officer continued, "And Amelia had me check the boots of the Algonquin workers who were there. They were all different."

Rhyme turned his attention to the boot. "What's the brand, do you think, Mel?"

Cooper was browsing through the NYPD's footwear database, which contained samples of thousands of shoes and boots, the vast majority of which were men's shoes. Most serious felonies involving physical presence at the scene were committed by men.

Rhyme had been instrumental in creating the expanded shoe and boot database years ago. He worked out voluntary arrangements with all the major manufacturers to have scans of their lines sent into the NYPD regularly.

After returning to forensic work, following his accident, Rhyme had stayed involved in maintaining the department's product and materials databases, including this one. After working on a recent case involving data mining he'd come up with an idea that was now used in many police departments around the country: He'd recruited (well, bullied) the NYPD into hiring a programmer to create computer graphics images that depicted the sole of each shoe in the database in different stages of wear-new, after six months, one year and two years. And then to show images of the soles of shoes worn by people who had splayed feet or were pigeon-toed. He'd also gotten the computer guru to indicate wear patterns as a function of height and weight.

The project was expensive but took surprisingly little time to get online and resulted in nearly instantaneous answers to the questions of the brand and age of shoe, and the height, weight and stride characteristics of the wearer.

The database had already helped in the identification of three or four perps.

His fingers flying over the keys, Cooper said, "Got a match. Albertson-Fenwick Boots and Gloves, Inc. Model E-20." He perused the screen. "Not surprising, they've got special insulation. They're for workers who have regular contact with live electrical sources. They meet ASTM Electrical Hazard Standard F2413-05. These're size eleven."

Rhyme squinted as he looked them over. "Deep treads. Good." This meant they would retain significant quantities of trace material.

Cooper continued, "They're fairly new so there're no distinctive wear marks that tell us much about his height, weight or other characteristic."

"I'd say he walks straight, though. Agree?" Rhyme was looking at the prints on his screen, broadcast from a camera over the examining table.

"Yes."

Sachs wrote this on the board.

"Good, Sachs. Now, Rookie, what's the invisible evidence you found?" Gazing at the plastic envelope labeled Coffee Shop Opposite Blast-Table Where Suspect Was Sitting.