The Burning Wire (Lincoln Rhyme 9)

"We know that."

"But the perp had to get the codes from inside headquarters in Queens. Either him or an accomplice. They're kept in hard copies and on a random code generator that's isolated from networks."

"So," the criminalist summarized, just to make sure, "no outside hackers, domestic or international."

"Next to impossible. I'm serious, Lincoln. Not a single rootkit--"

"Got it, Rodney. Any trace on his line from the coffee shop?"

"Prepaid cell connecting through a USB port. Went through a proxy in Europe."

Rhyme was tech enough to know that this meant the answer to his question was no.

"Thanks, Rodney. How do you get any work done with that music?"

The man chuckled. "Call me anytime."

The raucous hammering disappeared with the disconnecting click.

Cooper too was on the phone. He hung up and said, "I've found somebody in Materials Analysis at HQ. She's got a geology background. She knows a lot of the schools that have regular exhibits for the public. She's checking on volcanic ash and lava."

Pulaski, poring over the door, squinted. "Got something here, I think."

He pointed to a portion of the door near the top latch. "It looks like he wiped it off." He grabbed the magnifying glass. "And there's a burr of metal. Sharp . . . I think he cut himself and bled."

"Really?" Rhyme was excited. There's nothing like DNA in forensic work.

Sellitto said, "But if he cleaned it off, does it still do us any good?"

Before Rhyme could offer anything, Pulaski, still hunched over his find, mused, "But what would he have to clean it off with? Maybe spit. That's as good as blood."

This was going to have been Rhyme's conclusion. "Use the ALS."

Alternative light sources can reveal bodily fluids like traces of saliva, semen and sweat, all of which contain DNA.

All law enforcement agencies were now taking samples of DNA of suspects in certain types of offenses--sex crimes, for instance--and many were going further than that. If their UNSUB had committed a swabbable offense, he'd be in the Combined DNA Index System database, CODIS.

A moment later Pulaski, wearing goggles, paused the wand over a portion of the access door where he'd spotted the smear. There was a tiny yellowish glow. He called, "Yessir, got something. Not much."

"Rookie, you know how many cells are in the human body?"

"Well . . . no, I don't."

"Over three trillion."

"That's a lot of--"

"And do you know how many are needed for a successful DNA sample?"

He said, "According to your book, Lincoln, about a hundred."

Rhyme lifted an eyebrow. "Impressive." Then he added, "You think you have a hundred cells there in that massive smear?"

"Probably, I would think."

"You sure do. Sachs, looks like your swimming expedition wasn't in vain. If the battery had blown, it would have destroyed the sample. Okay, Mel, show him how to collect it."

Pulaski ceded the tricky task to Cooper.