"Radiation causes leukemia," Morse said assertively. "You don't have to be a genius to give someone cancer."

She's right, Chris realized. Many initial survivors of Hiroshima died of leukemia in the aftermath of the atomic bomb, as did many "survivors" of the Chernobyl disaster. Marie Curie died of leukemia caused by her radium experiments. You could cause sophisticated genetic damage with a metaphorically blunt instrument. His mind instantly jumped to the issue of access to gamma radiation. You'd have to consider physicians, dentists, veterinarians-hell, even some medical technologists had access to X-ray machines or the radioactive isotopes used for radiotherapy. Agent Morse's theory was based on more than wild speculation. Yet the basic premise still seemed ludicrous to him.

"It's been done before, you know," Morse said.

"What has?"

"During the late 1930s, the Nazis experimented with ways of sterilizing large numbers of Jews without their knowledge. They asked subjects to sit at a desk and fill out some forms that would take about fifteen minutes. During that time, high-energy gamma rays were fired at their genitals from three sides. The experiment worked."

"My God."

"Why couldn't someone do the same thing to an unsuspecting victim in a lawyer's office?" Morse asked. "Or a dentist's office?"

Chris pedaled harder but said nothing.

"You know that researchers purposely cause cancer in lab animals all the time, right?"

"Of course. They do it by injecting carcinogenic chemicals into the animals. And chemicals like that are traceable, Agent Morse. Forensically, I mean."

She gave him a skeptical look. "In an ideal world. But you said yourself, it takes time to die from cancer. After eighteen months, all traces of the offending carcinogen could be gone. Benzene is a good example."

Chris knit his brow in thought. "Benzene causes lung cancer, doesn't it?"

"Also leukemia and multiple myeloma," she informed him. "They proved that by testing factory workers with minor benzene exposure in Ohio and in China."

She's done her homework, he thought. Or someone has. "Have you done extensive toxicological studies in all these deaths?"

"Almost none of them."

This stunned him. "Why not?"

"Several of the bodies were cremated before we became suspicious."

"That's convenient."

"And in the other cases, we couldn't get permission to exhume the bodies."

"Again, why not?"

"It's complicated."

Chris sensed that he was being played. "I don't buy that, Agent Morse. If the FBI wanted forensic studies, they'd get them. What about the families of these alleged victims? Did they suspect foul play? Is that how you got into this case? Or was it your sister's accusation that started it all?"

Two big touring motorcycles swept around a long curve ahead, their lights illuminating the rain.

"The families of several victims suspected foul play from the beginning."

"Even though their relatives died of cancer?"

"Yes. Most of the husbands we're talking about are real bastards."

Big surprise. "Had all of these alleged victims filed for divorce?"

"None had."

"None? Did the husbands file, then?"

Morse looked over at him again. "Nobody filed."

"Then what the hell happened? People consulted this lawyer but didn't file?"

"Exactly. We think there's probably a single consultation-maybe two visits, at most. The lawyer waits for a really wealthy client who stands to lose an enormous amount of money in his divorce. Or maybe the client stands to lose custody of his kids. But when the lawyer senses that he has a truly desperate client-a client with intense hatred for his spouse-he makes his pitch."

"That's an interesting scenario. Can you prove any of it?"

"Not yet. This lawyer is very savvy. Paranoid, in fact."

Chris gazed at her in disbelief. "You can't even prove that any murders have occurred, much less that anyone specific is involved. You've got nothing but speculation."

"I have my sister's word, Doctor."

"Spoken on her deathbed, after a severe stroke."

Morse's face became a mask of defiant determination.

"I'm not trying to upset you," Chris said. "I'm very sorry for your loss. I see that kind of tragedy week in and week out, and I know what it does to families."

She said nothing.

"But you have to admit, it's a pretty elaborate theory you've developed. It's Hollywood stuff, in fact," he said, recalling Foster's words. "Not real life."

Morse did not look angry; in fact, she looked mildly amused. "Dr. Shepard, in 1995, a forty-four-year-old neurologist was arrested at the Vanderbilt Medical Center with a six-inch syringe and a four-inch needle in his pocket. The syringe was filled with boric acid and salt water. I'm sure you know that solution would have been lethal if injected into a human heart."

"That's about the only thing a four-inch needle's good for," Chris thought aloud.

"The neurologist was planning to murder a physician who'd been his supervisor when he was a resident there. When police searched a storage unit he owned, they found books on assassination and the production of toxic biological agents. They also found a jar containing ricin, one of the deadliest poisons in the world. The neurologist had planned to soak the pages of a book with a solvent mixture that would promote the absorption of ricin through the skin." Morse looked over at Chris with a raised eyebrow. "Is that elaborate enough for you?"

Chris shifted down two gears and pedaled ahead.

Morse quickly rode alongside him again. "In 1999, a woman in San Jose, California, was admitted to the hospital with nausea and blinding headaches. They gave her a CAT scan and found nothing. But a technician had laid the woman's earrings down next to a stack of unexposed X-ray film. When they were developed, the tech saw an apparent defect on each of the films. It was very distinctive. He finally figured out that one of the woman's earrings had exposed the films."

"The earrings were radioactive?"

"One of them was. The woman's husband was a radiation oncologist. The police called in the Bureau, and we discovered that her cell phone was as hot as a piece of debris from Chernobyl. Turned out her husband had hidden a small pellet of cesium inside the phone. Of course, by that time he'd put the pellet back into its lead-lined case at his office. But the traces were still there."

"Did she develop cancer?"

"She hasn't yet, but she may. She absorbed hundreds of times the permissible exposure."

"What happened to the radiation oncologist?"

"He's in San Quentin now. My point is, doctors aren't immune to homicidal impulses. And they're capable of very elaborate plans to carry them out. I could cite dozens of similar cases for you."

Chris waved his right hand. "Save your breath. I know some stone-crazy doctors myself." Despite his casual retort, he was sobered by Morse's revelations.

"There are four and a half thousand doctors in Mississippi," she said. "Add to that about five thousand dentists. Then you have veterinarians, med techs, university researchers, nurses-a massive suspect pool, even if you assume the killer is from Mississippi. And I've only been onto this theory for seven days."

As Morse spoke, Chris realized that the apparent enormity of the task was illusory; it only existed because of a lack of baseline information. "You've got to find the cause of death in these people-or rather the cause of the cause, the etiology of these blood cancers. If it is radiation, you could start narrowing your suspect pool pretty quickly."

Her voice took on an excited edge. "An expert I talked to says radiation is the surest and simplest method."

"But you don't have forensic evidence? No radiation burns, or strange symptoms noted long before the cancer was diagnosed?"