The Steel Kiss (Lincoln Rhyme 12)

"Never heard of it."

"Number of uses, dyes, pesticides, for instance. But the number one: explosives."

Sachs pointed to the chart from the murder scene itself, the construction site where Unsub 40 beat Todd Williams to death near the club a couple of weeks ago. "Ammonium nitrate."

Fertilizer--and the major explosive ingredient in homemade bombs, like the one that destroyed the Oklahoma City federal building in the '90s.

"So," Pulaski said slowly, "you think there's more to it than a robbery? The unsub was, I don't know, buying bomb ingredients near Forty Degrees North or the construction site and Williams saw it?" He tapped the computer screen. "And look at this." In trace collected near a footprint at the mall loading dock was a small amount of motor oil.

The second ingredient in a fertilizer bomb.

Sachs sighed. Were there terrorist dimensions to this unsub? Though the murder had occurred at a jobsite, these chemicals would not have been used for commercial demolition. "Keep going."

"More phenol. Like we found at the first murder scene."

"If it's shown up twice it's significant. What's that used for?"

Pulaski called up a profile of the chemical. "Phenol. A precursor in making plastics, like polycarbonates, resins and nylon. Also in making aspirin, embalming fluid, cosmetics, ingrown toenail cures."

Forty had big feet. Maybe nail problems.

"Then this." He was transcribing a long list of other chemicals onto a whiteboard evidence chart.

"Mouthful," she said.

"Profiles as makeu

p. Cosmetics. No idea of the brand."

"Need to know who makes it. Have somebody in HQ track it down."

Pulaski sent the request.

Then they returned to the evidence. He said, "Have a tiny shaving of metal. From the footprint in the hallway leading to the loading dock."

"Let me see it."

Pulaski called up the photos.

Hard to make out to the eye--whether naked or stylishly covered with drugstore-bought reading glasses, which Sachs had had to resort to lately.

She cranked up the magnification and studied the shiny bit. Then turned to the second laptop, typed her way into an NYPD database of metal trace, which, as it turned out, Lincoln Rhyme had established several years earlier.

Together they scanned the database. "Something similar there," said Pulaski, standing over her shoulder, as he pointed at one of the photos.

Yes, good. The tiny fleck was from the process of sharpening a knife, scissors or razor.

"It's steel. He likes a sharp blade." He'd beaten the victim to death outside 40deg North but that didn't mean he wasn't interested in dispatching victims with other weapons as well.

On the other hand, he might recently have done nothing more than carved up the family's chicken dinner with a knife he'd just dramatically edged first, tableside.

Pulaski continued, "And some sawdust. Want to see?"

She looked at the microscopic images. The grains were very fine.

"From sanding, you think?" she mused. "Not sawing?"

"I don't know. Makes sense."