In an inspired if somewhat misguided bid at camouflage, the task force’s chemical surveillance truck had been painted to look like an exterminator’s vehicle, complete with a giant mouse cowering from a man wearing a respirator. Fisher thought Kowalski had posed for both images, though the mask made it difficult to tell.

“You’re a barrel of fucking laughs,” said the DIA agent, who was wearing a hazmat suit and standing in Mrs. DeGarmo’s kitchen. Two specially trained investigators were downstairs going over the basement with chemical detection gear. Two others were working upstairs in Faud Daraghmeh’s apartment.

“Listen, if you’re not going to do anything, why don’t you go and start interviewing some of the neighbors,” suggested Kowalski.

“Waste of time,” said Fisher. He got up and poured himself another cup of coffee.

“How do you know it’s a waste of time?” asked Kowalski.

Fisher shrugged.

“You ought to be wearing a suit,” said Kowalski.

“I am wearing a suit,” said Fisher.

“You know what I mean.” He began fiddling with the respirator unit.

“This is one hundred percent natural fibers,” said Fisher, pulling at his sleeve. “Protects against anything. I could pour this cup of coffee on the pants and never even feel it.”

“Go right ahead,” said Kowalski.

He was just pulling on the mask when one of the two men who’d been upstairs came down through the front hallway.

“Nothin’,” said the expert.

“Shit,” said Kowalski.

“What’d you expect?” asked Fisher.

“What’d I expect? You’re the one who called the team in. Jesus, Fisher.”

Expecting Kowalski to process more than one piece of information at a time clearly violated the principle of chemical osmosis.

“Well, let me take a look,” Fisher told him, starting for the hallway.

“Don’t screw up the place. We need photos first,” said the DIA agent.

“What for, a spread in House and Garden?”

Fisher found the other investigator in the bathroom, where he was reinstalling the trap under the sink.

“I’ll be out of here in a minute,” the man told Fisher.

“Take your time,” the FBI agent told him. He went to the medicine cabinet. Mrs. DeGarmo’s tenant was a Gillette man and preferred Bayer over the generic brands. Faud Daraghmeh couldn’t seem to settle on an allergy medicine, however: He had a dozen, from generic store brands to Sudafed. No prescription medicines, though. And nothing more revealing.

“They find anything in the basement?” the investigator asked as Fisher closed the medicine cabinet.

“Not that I heard. How about you?”

“Used ammonia to clean.”

“That mean anything?”

“Not particularly. I did think of one thing.”

“What’s that?” asked Fisher.

“He didn’t brush his teeth.”

“Maybe he just took his toothbrush,” said Fisher. He went back to the medicine cabinet. “He shaved.”

“Yeah?”

“You found hairs around?”

“Oh, yeah.”

The bedroom had a small, single bed with a pair of sheets and a thin blanket. A small desk and chair were the only other pieces of furniture; the drawers were empty except for a paperback dictionary. The closet had a few shirts and pants in it, and two suits that looked as if they’d come from a thrift shop. There were no papers that Fisher could find in any of them.

“Damn it, Fisher. I told you we want to photograph the place,” said Kowalski. He was still wearing his suit but carried the respirator and face shield in his hand. “And we’re going to dust for fingerprints. Don’t touch anything.”

Fisher resisted the temptation to smear the doorknobs and walked back out through the apartment. The living room furniture-it was included in the $1,093 a month rent, according to Mrs. DeGarmo-consisted of a pre-World War II couch, a marble coffee table that had once moved around on miniature wheels but was now propped off the floor with matchbooks, and a two-year-old thirty-two-inch Sony television. The lab people had taken the cushions off the sofa: The foam in them was so old it was degenerating into formaldehyde.

A phone line ran along the front wall. It had been cut open, slit as if for a splice, though Fisher couldn’t see any or a box for an outlet. He bent down to the floor, looking at the line.

“What are you doing?” Kowalski asked.

“Matchbooks,” said the agent, pointing to them.

“Clues, huh?” Kowalski scowled. He went to the coffee table and lifted it. “Sucker’s heavy.”

“I’ll bet,” said Fisher, standing up.

“Jesus, Fisher, aren’t you grabbing the matchbooks?”

“Nah.”

“But you just said they were important.”

“No, I just pointed them out. Once upon a time, the person who lived here smoked. Or had access to a smoker.”

Kowalski pushed the coffee table a few inches from its spot and put it down with a thud. He picked up the matchbooks, which bore Marlboro logos.

“So he was a smoker,” said the DIA agent triumphantly. “All scumbags are.”

“Those are the landlady’s,” said Fisher. “And they’re at least five years old. Why do you think he shaved?”

The men working in the basement had several possible hits on two small saucers that had been placed near the boiler.

“Something like strychnine, probably,” one of the men told Fisher after they’d finished going over the place.

“Like strychnine.”

“We’re going to have to do tests back at the lab. But it makes sense. Rat poison. She had a rat problem, right? Or mice.”

“So you don’t really know what it was?”

“Not until the tests.”

“And you checked the sink?” asked Fisher.

“Cleaned thoroughly. Bleach.”

“Bleach?”

The expert pointed to a set of bottles under the large tub. “It all checks out. Clorox. We’ll double-check.”

Fisher walked to the back of the long, narrow room; there was an outside door leading to a small garden courtyard. A crime scene technician was just setting up to see if he could get prints from the door and doorknob.

“Mind if I go outside?”

“Hang on a second,” said the man.

Fisher stepped to the side, looking at the shelves of stacked flowerpots. There was a bag on the floor of potting soil.

“You check the dirt?” he asked the chemical expert.

“Yeah. It’s dirt.”

Fisher looked at the bag. Unlike the pots, it was very new.

“Could you use the dirt for lab work?” he asked the expert.

“Nah.”

Fisher took the bag with him outside. While there had obviously been a garden here once, it was now overgrown with weeds. He emptied the bag of dirt on the small strip of concrete once used as a patio next to the house.

“Whatcha looking for?” Macklin asked, coming out from the basement.

“Here he is, the Homeland Security commander himself,” said Fisher, “come to oversee the troops.”

“So, what are you doing?”

“I always like to find the dirt in a case,” said Fisher. He looked for something to sift through the soil with, but there was nothing nearby. He went back inside to the shelves where the pots were; an old watering can with tools sat on the floor. It was dark in the corner; he brought the tools out with him and sifted through the dirt with a small hand cultivator, a three-pronged tool that looked a bit like a cross between a miniature rake and a claw.

“Something?” asked Macklin.

“Nada,” said Fisher. He started to toss the cultivator back into the can, then got another idea and dumped it out on the ground.

In the pile of shovels and sticks lay two new and loaded autoinjectors.

“Now, those are worth dusting,” said Fisher, pointing to them. “And then we have to figure out what they are.”