“How long ago did you say Ms. Edgerton vanished?” he asked.

“It was twenty-five years ago,” said Jane.

“And does that period of time account for the current condition of her body?”

“We know this is Lorraine Edgerton, based on the dental records.”

“And we also know it doesn’t take centuries to mummify a body,” added Frost.

“Yes, but could she have been killed far more recently than twenty-five years ago?” said Zucker. “You said she was kept alive long enough for her bullet wound to begin healing. What if she was kept a prisoner for far longer? Could you turn a body into a mummy in, say, five years?”

“You think this perp could have kept her captive for decades?”

“I’m merely speculating, Detective Frost. Trying to understand what our unknown subject gets out of this. What could drive him to perform these grotesque postmortem rituals. With each of the three victims, he went to a great deal of trouble to keep her from decaying.”

“He wanted them to last,” said Lieutenant Marquette, chief of the homicide unit. “He wanted to keep them around.”

Zucker nodded. “Eternal companionship. That’s one interpretation. He didn’t want to let them go, so he turns them into keepsakes that will last forever.”

“So why kill them at all?” asked Detective Crowe. “Why not just keep them as prisoners? We know he kept two of them alive long enough for their fractures to start healing.”

“Maybe they died natural deaths from their injuries. From what I read in the autopsy reports, there are no definitive answers as to cause of death.”

Jane said, “Dr. Isles was unable to make that determination, but we do know that the Bog Lady…” She paused. Bog Lady was the new victim’s nickname, but no detective would ever say it in public. No one wanted to see it splashed across the newspapers. “We know that the victim in the trunk suffered fractures of both legs, and they may have become infected. That could have caused her death.”

“And preservation would be the only way to keep her around,” said Marquette. “Permanently.”

Zucker looked down, once again, at the photo. “Tell me about this victim, Lorraine Edgerton.”

Jane slid a folder across to the psychologist. “That’s what we know about her so far. She was a graduate student working in New Mexico when she vanished.”

“What was she studying?”

“Archaeology.”

Zucker’s eyebrow shot up. “Do I sense a theme here?”

“It’s hard not to. That summer, Lorraine was working with a group of students at an archaeological dig in Chaco Canyon. On the day she vanished, she told her colleagues that she was going into town. She left on her motorbike in the late afternoon and never came back. Weeks later, the bike was found miles away, near a Navajo reservation. From what I gather about the area, there’s not much in the way of population. It’s mostly open desert and dirt roads.”

“So there are no witnesses.”

“None. And now it’s twenty-five years later, and the detective who investigated her disappearance is dead. All we have is his report. Which is why Frost and I are flying out to New Mexico to talk to the archaeologist who was director of the dig. He was one of the last people who saw her alive.”

Zucker looked at the photos. “She appears to have been an athletic young woman.”

“She was. A hiker, a camper. A woman who spent a lot of time with a shovel. Not the kind of gal who’d give up without a fight.”

“But there was a bullet in her leg.”

“Which may have been the only way this perp could control his victims. The only way he could bring down Lorraine Edgerton.”

“Both of Bog Lady’s legs were broken,” Frost pointed out.

Zucker nodded. “Which certainly makes the case that the same unsub killed both women. What about the bog victim? The one found in the trunk?”

Jane slid him the folder for Bog Lady. “We have no ID on her yet,” she said. “So we don’t know if she’s linked in any way to Lorraine Edgerton. NCIC is running her through their database, and we’re just hoping that someone, somewhere reported her missing.”

Zucker scanned the autopsy report. “Adult female, age eighteen to thirty-five. Excellent dentition, orthodontic work.” He looked up. “I’d be surprised if her disappearance wasn’t reported. The method of preservation must tell you what part of the country she was killed in. How many states have peat bogs?”

“Actually,” Frost said, “a lot of them. So that doesn’t narrow it down a great deal.”

“Get ready,” Jane warned with a laugh. “Detective Frost is now Boston PD’s official bog expert.”

“I spoke to a Dr. Judith Welsh, a biologist over at University of Massachusetts,” said Frost. He pulled out his notebook and flipped it open to the relevant pages. “Here’s what she told me. You can find sphagnum wetlands in New England, Canada, the Great Lakes, and Alaska. Anywhere that’s both temperate and wet. You can even find peat bogs in Florida.” He glanced up. “In fact, they found bog bodies not far from Disney World.”

Detective Crowe laughed. “Seriously?”

“Over a hundred of them, and they’re probably eight thousand years old. It’s called the Windover Burial Site. But their bodies weren’t preserved. They’re just skeletons, really, not like our Bog Lady at all. It’s hot down there so they decomposed, even though they were soaking in peat.”

“That means we can eliminate any southern bogs?” said Zucker.

Frost nodded. “Our victim’s too well preserved. At the time of her immersion, the water had to be cold, four degrees Celsius or lower. That’s the only way she’d come out looking as good as she does.”

“Then we’re talking about the northern states. Or Canada.”

“Canada would present a problem for our perp,” Jane pointed out. “You’d have to bring a dead body over the border.”

“I think we can eliminate Alaska as well,” said Frost. “There’s another border crossing. Not to mention a long drive.”

“It still leaves a lot of territory,” Zucker said. “A lot of states with bogs where he could have stashed her body.”

“Actually,” said Frost, “we can narrow it down to ombrogenous bogs.”

Everyone in the room looked at him. “What?” said Detective Tripp.

“Bogs are really cool things,” said Frost, launching enthusiastically into the topic. “The more I find out about them, the more interesting they get. You start off with plant matter soaking in stagnant water. The water’s so cold and low in oxygen that the moss just sits there not decaying, piling up year after year till it’s at least a couple of feet deep. If the water’s stagnant, then the bog’s ombrogenous.”

Crowe looked at Tripp and said drily, “A little knowledge is a dangerous thing.”

“Is any of this really relevant?” asked Tripp.

Frost flushed. “Yeah. And if you’d just listen, maybe you’d learn something.”

Jane glanced at her partner in surprise. Rarely did Frost show irritation, and she hadn’t expected him to do so over the subject of sphagnum moss.

Zucker said, “Please continue, Detective Frost. I’d like to know exactly what makes a bog ombrogenous.”

Frost took a breath and straightened in his chair. “It refers to the source of water. Ombrogenous means it doesn’t get any water from streams or underground currents. Which means it gets no added oxygen or nutrients. It’s entirely rain-fed and stagnant, and that makes it superacidic. All the characteristics that make it a true bog.”

“So it isn’t just any wet place.”

“No. It has to be fed only by rainwater. Otherwise they’d call it a fen or a marsh.”

“How is this important?”

“Only real bogs have the conditions you need to preserve bodies. We’re talking about a specific kind of wetland.”

“And would that limit where this body was preserved?”

Frost nodded. “The Northeast has thousands of acres of wetland, but only a small fraction of them are true bogs. They’re found in the Adirondacks, in Vermont, and in northern and coastal Maine.”