“And yes, Alex, arsenic is introduced into drinking water through the dissolution of minerals and ores on the earth’s surface. Sometimes aggravated by industrial waste. It’s in a lot of the fish and meat you eat. But if Grooten was exposed to a supply of contaminated water, where she worked or where she lived, she wouldn’t be the only one getting sick. The whole neighborhood would have been in bad shape after a while.”

“What are you figuring, blondie? She drank too much tap water, fell into a limestone box and the lid dropped on it?”

“You know Battaglia’s going to ask me if there’s any chance her death could have been accidental. I’m just trying to rule out the obvious.”

“Of course there have been accidental poisonings. We had a case last year where a guy who did professional woodworking breathed in the fumes from some chemically treated lumber. Absorbed the stuff through his mucous membranes because he was just too stubborn to use a mask on wood that had been coated with an arsenic compound. You can inhale it, absorb it, and ingest it. None of those methods are recommended.”

“Does it manifest any symptoms over time?”

“Sure. If it were just a mild poisoning, I’d expect the patient to complain of nausea, chills, loss of appetite, intestinal upset, apathy. Small doses would make you sick, but they wouldn’t necessarily kill you. The more acute cases begin to show skin lesions, chronic headaches, the metallic taste which results in that garliclike odor, the liver damage apparent here at autopsy.”

“Can you give me any idea how long this was going on, doc?”

“The hair sample should be a big help with that. It will give us a poisoning time line.”

“How so?”

“Figure that the average growth rate for human hair is one and a half centimeters a month. Every millimeter sample represents about two days’ growth. I’d expect to be able to tell when Grooten was exposed to her first significant dose of arsenic once we get that result. And from the looks of things today, we’ll probably find a much greater concentration-five or six times as much-in the hair closest to her scalp.”

“Did you find any trace evidence on the body or inside the coffin, anything that might link us to the guy who did this?”

“I’ve saved the linen binding. Has some age to it. Probably was taken off some other antiquity and wrapped around Grooten. So you’re likely to have some transfer material or residue from the first subject. More likely that than from the killer.”

“Prints?”

“I never thought of you as an optimist, Mike. The lab can look it over. I’d think whoever had this much time to deal with a corpse had latex gloves on. You don’t have to be a doctor. Every drug and hardware store sells them.”

“And where do you shop for arsenic?” I asked.

“It’s in insecticides like Paris green. It’s in poison gases. Have you confirmed that she had a connection at the Metropolitan Museum, like you thought yesterday?”

“Yeah.”

“Arsenic is a very common ingredient in pigments, Alex. Any art museum would have a surprisingly good supply of deadly poisons. Lye and white lead and arsenic make for brilliant colors but a lousy diet, and they’re likely to be in any serious artist’s stash of pigments.” Kestenbaum turned to Chapman. “I’ve bagged her clothes for you, Mike.”

He tossed us each a pair of latex gloves and pointed at a bunch of brown paper bags standing on the far end of the table at which we were seated.

I stood up and opened the first of them, removing a bra. It was old and worn thin, and the writing on the label had been bleached off after many washings. It was a small size. The second bag held the deceased’s panties. Like the bra, they were a dingy shade of off-white, from age and repeated cycles of laundering. The third bag contained a pair of women’s slacks, size 6, poorly made of a coarse plaid wool. They were worn around the bottom of the pant legs and had pilling all over the seat. The brand name was that of one of the cheap mailorder companies.

The fourth bag held a woman’s crewneck sweater.

“What’s so fascinating, Coop?”

“It doesn’t belong to the same shopper who bought the other pieces.”

“How come?”

“First of all, it’s cashmere. It’s also not her size.” I held the sweater up to examine it. It was much larger than the small-boned Grooten would have worn.

“Third, the label is one of the most expensive shops on Madison Avenue. Where’s your Polaroid?”

Kestenbaum pointed to the door. “Turn right, there’s one in the supply closet at the end of the hallway.”

“Submit all this to the lab, but I want to do some checking on the sweater. Maybe we can find out whether she bought it herself, or if someone gave it to her as a gift.” I handed it to Mike to photograph, to record the detail of the cable stitching and the style of the collar and cuffs. The item had not been mass-produced. It was doubtful that many of these pale peach-colored knits had been sold. “This probably retailed for more than five hundred dollars.”

“On a museum intern’s salary? I don’t think my entire wardrobe between the time I was born and the age of thirty cost that much,” Mike said.

Kestenbaum picked up a white letter-sized envelope from his desk. “You’ll want to voucher this, too. I found it in the pocket of her slacks. Maybe it will tell you where Ms. Grooten left her belongings when she went for her last meal.”

I lifted the flap and took out a square red ticket, one inch in size, bearing the number 248. It looked like the stub of a receipt from a coat-check concession, somewhere between the morgue and Cairo.

“See any Hessians?” Mike Chapman called out to Mercer Wallace, who was leaning against the massive granite stones that formed a wall bordering the grouping of monasteries that had been moved from Europe to this rocky cliff three-quarters of a century ago. It was shortly after twelve on a sunny May afternoon, and we climbed the circular walk to join Mercer on the ledge overlooking the Hudson River.

“You are standing, my friends, on the highest piece of land on the island of Manhattan, accessible by the deepest subway station in the city-not that you would give a thought to any form of public transportation, Coop,” Mike continued. “Almost lost to the Brits in the affair of the outposts.”

Mercer turned to listen to the military history of this extraordinary piece of open public land on the northern end of Manhattan, his huge frame posed against the wide stretch of water below.

“General Washington left the garrison here and headed north, while Cornwallis surrounded this place with warships, Highlanders, British troops, and Hessians. They took the fort, killed most of the Americans, and were encamped here until these heights were refortified. That’s why the Long Hill outwork was renamed for William Tryon, the last English governor of New York.”

The Cloisters Museum stood on a spectacular hilltop in Fort Tryon Park, the last of the New York City parklands designed by Frederick Law Olmsted. John D. Rockefeller had given the city the buildings and more than sixty acres of unique urban land, with paved walks, terraces, and rocky terrain covering the area from the old ramparts of the original fort to the peak on which the imported ruins had been reset and enclosed in a contemporary setting.

My eyes swept the vista, leaving the river to follow the pathway that led directly down from our perch through the densely wooded area. Katrina Grooten had set off from the museum along one of those sloping walks on an evening last June, into the hands of a modern-day highwayman who had pulled her into the thickets that shielded them from view while he assaulted her.

“Hiram Bellinger is waiting for us inside.” Mercer led us around the impressive structure and down to the entrance that faced the parking lot. The Romanesque-style doorway, adorned with animals and birds, both real and imaginary, led to a series of arched steps. We were among only a handful of visitors, and I felt as though I had stepped back a few centuries into a medieval church as I made my way upward, passing the occasional window framed with tiny panes of leaded glass.