The Burial Hour (Lincoln Rhyme 13)

Ercole said, "Beatrice has provided a chemical chart here. Should we write that down?"

Rhyme glanced at the molecular diagram. "No, not necessary. We've got what we need. Triacylglycerols--or triglycerides."

"What are they?" Spiro asked.

"Fat basically. They're energy reserves for living things. Molecules that contain glycol and three fatty acid chains. Hence, tri-glyceride. They're found in both plants and animals. But animal fats tend to be saturated."

"What does that mean?" Rossi made this inquiry.

"In a nutshell, saturated fats--the bad ones, if you listen to the health-minded--are so named because their carbon chains are saturated with hydrogen. This makes them more solid than unsaturated fats, which have less hydrogen." He nodded at the diagram. "These are missing some hydrogen and therefore it is a plant fat."

"But what kind?" Ercole asked.

"The sixty-four-thousand-dollar question."

"The...what? I am not understanding," Beatrice said.

"American cultural reference from a long time ago, fifty, sixty years or so."

The officer translated for Beatrice, who gave a rare smile and said something, which Ercole translated: "She said that is not so 'long ago,' compared with cultural references in Italy."

Sachs laughed.

Rhyme said, "We need to find out what plant. Is there a database of plants in the Scientific Police?"

Beatrice's response was that there was one in Rome. She would go online and search it. She typed and spoke to herself as she did so. "Allora. A triglyceride molecule, unsaturated, una hydrocarbon chain, twenty-two carbon atoms in way of length. Dark green, the pigment. What plant, what plant...?" Finally she nodded. "Bene. I have gotten it. But helpful, I am not thinking so much. It is olive oil."

Rhyme sighed, then glanced at Rossi. "How much olive oil would you say is produced in Italy?"

The inspector, in turn, handed off to Ercole. This would be, of course, his area of expertise. The young officer answered, "About four hundred and fifty thousand tons every year. We're the world's second-largest producer." He grimaced and added defensively, "But we are closing in on Spain."

How helpful is this? Rhyme thought, irritated. It could have come from anywhere in the country. "Hell."

This was the most frustrating occurrence in forensic work, struggling to discover a clue, only to learn that while it probably did have some connection with the perpetrator, the substance was so common that it was useless forensically.

Then Ercole said something to Beatrice and she stepped away, returning a moment later with some photographs.

He studied them carefully.

"What, Ercole, you see something?" Rhyme asked.

"I believe I do, Capitano."

"And?"

"The reference on the chart--to the organic material. Bits of solids. Look at the photo."

Rhyme glanced at the images. He could see hundreds of tiny dark fragments.

Ercole added, "Since we now know about the olive oil, I would say that this trace is not olive oil alone. It is pomace. That is the paste left over after the pressing of the olives."

Spiro said, "So this might have come not from a restaurant or someone's home but from a producer?"

"Yes."

Narrowing things down some. But how much? He asked, "Do you have a lot of producers here?"

"In Campania, our region, we don't have as many as in Calabria, farther south. But still many, many, yes."