“Thank you.” Frock nodded.
“In it, do you apply the ‘Gambler’s Ruin’ scenario to your theory of evolution? I always thought that backed up your hypothesis rather well, especially if you assume most genera start out close to the absorbing boundary.”
Frock sat up in his wheelchair. “Well, ah, I was planning to make certain references to that in my next book.” He seemed at a loss for words.
Pendergast nodded to the officers, who readjusted the barrier. “I need your help, Dr. Frock,” he said in a lower tone.
“Certainly,” Frock said amiably. Margo was amazed at how quickly Pendergast had won Frock’s cooperation.
“I must ask, first of all, that this discussion be kept among ourselves for the time being,” said Pendergast. “May I have your assurance? And that of Ms. Green?”
“Of course,” said Frock. Margo nodded.
Pendergast motioned to one of the officers, who brought forward a large plastic bag marked EVIDENCE. From it he removed a small, dark object, which he handed to Frock.
“What you’re holding,” he said, “is the latex cast of a claw found embedded in one of the children that were murdered last weekend.”
Margo leaned forward for a closer look. It was about an inch long, perhaps a little less, curved and jagged.
“A claw?” Frock said, bringing the object close to his face and examining it. “Very unusual. But I’d guess it’s a fake.”
Pendergast smiled. “We haven’t been able to identify its source, Doctor. But I’m not sure it’s a fake. In the root canal of the claw we found some matter, which is now being sequenced for DNA. The results are still ambiguous, and our tests are continuing.”
Frock raised his eyebrows. “Interesting.”
“Now this,” said Pendergast, reaching into the bag and withdrawing a much larger object, “is a reconstruction of the instrument that raked the same child.” He handed it to Frock.
Margo looked at the cast with disgust. At one end, the latex was mottled and uneven, but at the other, details were clear and well-defined. It ended in three hooked claws: a large central claw, and two shorter talons on either side.
“Good heavens!” said Frock. “This looks saurian.”
“Saurian?” asked Pendergast dubiously.
“Dinosaurian,” said Frock. “Typical ornithischian forelimb, I should say, with one difference. Look here. The central digital process is thickened enormously, while the talons themselves are undersized.”
Pendergast raised his eyebrows in mild surprise. “Well, sir,” he said slowly, “we’d been leaning toward the big cats, or some other mammalian carnivore.”
“But surely you know, Mr. Pendergast, that all mammalian predators have five digits.”
“Of course, Doctor,” said Pendergast. “If you would indulge me for a moment, I’d like to describe a scenario to you.”
“Certainly,” said Frock.
“There is a theory that the murderer is using this—” he hefted the forelimb—“as a weapon to rake his victims. We feel that what I’m holding might be the impression of an artifact of some kind, something made by a primitive tribe out of, say, a jaguar or lion forelimb. The DNA appears to be degraded. It may be an old artifact, collected by the Museum a long time ago, then stolen.”
Frock’s head lowered until his chin was on his chest. The silence stretched out, broken only by the shuffling of the policemen by the barricade. Then Frock spoke.
“The guard who was killed? Did his wounds show evidence of a broken or missing claw?”
“Good question,” Pendergast said. “See for yourself.” He slid his hand into the plastic bag and removed a heavy plaque of latex, a long rectangle with three jagged ridges down its middle.
“This is a cast of one of the guard’s abdominal wounds,” Pendergast explained. Margo shuddered. It was a vile-looking thing.
Frock peered at the deep ridges intently. “The penetration must have been remarkable. But the wound shows no indication of a broken claw. Therefore, you are suggesting that two such artifacts are in use by the murderer.”
Pendergast looked a little uncomfortable, but nodded.
Frock’s head sank once more. The silence went on for minutes. “Another thing,” he suddenly said, quite loudly. “Do you see how the claw marks draw together slightly? How they are farther apart at the top than at the bottom?”
“Yes?” said Pendergast.
“Like a hand clenching into a fist. That would indicate flexibility in the instrument.”