Carlton settled back with a dubious grunt.
“This brings us to the cross.” The next slide came up. “Our art expert has identified this as a rare example of a seventeenth-century Tuscan cross, commonly worn by the noble classes. It is made of gold and silver, layered, fused, and hand-chased to produce a rather interesting effect known as lamellés fines. It was then set in wood, which has largely burned away.”
“How much’s it worth?” Carlton said, asking an intelligent question for a change.
“Given the precious stones, eighty, perhaps one hundred thousand dollars. Undamaged, that is.”
Carlton whistled.
“The cross was found around the neck of the victim, touching his skin. Here is a photograph of it at the scene of the crime, still around the victim’s neck.”
The next slide came up, prompting noises of disgust and disbelief.
“As you can see, the cross heated to the point of melting, deeply burning the skin where it lay. But observe that the surrounding flesh is not scorched or even reddened. Something—and I really can’t say what—selectively heated the cross without heating the surrounding skin. The cross then partially melted and burned itself into the victim’s flesh in situ.
“And here”—he brought up the next image—“is an electron micrograph at 3,000x, showing this extraordinary pitting along the silver—but not the gold—surface of the cross. I can’t account for this, either. I suspect it might have been caused by an intense and prolonged dose of radiation that seems to have stripped off the top layers of electrons and vaporized part of the metal. It acts much more strongly on silver than on gold. Again, I have no idea why.”
Carlton was on his feet. “Can we have this in plain English?”
“Of course,” Dienphong said dryly. “Something heated up and melted the cross without heating up anything around it. I guess it must have been some kind of radiation that was taken up by metal more strongly than flesh.”
“Like maybe the same radiation that burned the hoofprint?”
Carlton, Dienphong had to admit, was not as stupid as he pretended to be.
“A good possibility.”
Pendergast raised a finger.
“Agent Pendergast?”
“Were there any signs of radiation burns or heating in any other surfaces in the room?”
An even better question. “Yes, in fact, there were. The bedposts, which were varnished pine, showed signs of heat stress, as did the wall behind the bed, which was painted pine. In some areas, the paint had softened and bubbled.”
He moused his way through the on-screen menu and pulled up another image. “Here’s a cross section of the wall, showing four layers of paint. Now here’s yet another small mystery: only the lowest layer of paint seems to have heated up and bubbled. The others were undisturbed and remained chemically unaltered.”
“Did you analyze all four layers of paint?” Pendergast asked.
Dienphong nodded.
“Was the bottom layer a lead-based paint?”
Dienphong felt a sudden surprise. He quickly saw where the line of questioning would lead, and it was something that he had not thought of. “Let me check the book.” He flipped through the lab reports, organized and categorized in a three-ring binder labeled Brimstone. All FBI investigations get a nickname, and this was the one he had given this case. Melodramatic, perhaps, but appropriate.
He looked up from the binder. “Yes, as a matter of fact it was lead-based.”
“And the rest were not?”
“That’s correct.”
“Further proof that we are dealing with some kind of radiation.”
“Very good, Agent Pendergast.” It was the first time in his career that an FBI agent had beaten him to a conclusion. This Pendergast was living up to his reputation. Dienphong cleared his throat. “Any other questions or comments?”
Carlton sat down again, raised a weary hand.
“Yes?”
“I’m missing something. How could something affect the bottom layer of paint and not the upper ones?”
Pendergast turned. “It was the lead in the paint that reacted, like the metal in the cross. It absorbed the radiation more strongly. Was there any radioactivity present at the site, Doctor, during follow-up investigation?”
“None whatsoever.”
Carlton nodded. “Check into that, Sam, will you?”
“Of course, sir,” one of the junior agents replied.
Dienphong went to the next image. “Here’s the final image: a close-up of a section of the cross. Note the very localized melting, completely inconsistent with a convective source of heat. Again an indication that radiation played a role.”
“What type of radiation would selectively heat metal more than flesh?” Pendergast asked.
“X-rays, gamma rays, microwave, far infrared, certain wavelengths in the radio spectrum, not to mention alpha radiation and a flux of fast neutrons. This is not very unusual. What is unusual is the intensity.”