A gurney had been rolled up the drive. On it lay a black body bag, unzipped, ready. Beside it were the same CSS techs who’d worked the site less than twenty-four hours earlier. One held a video camera, the other a Nikon.

Slidell and I got out. The sky had morphed to a foggy gray. The color of Ajax’s lonely rooms, I thought.

The air was cool and damp. The frost-coated lawn pulsed red and blue. As Slidell and I crossed it, my insides felt like a lump of granite.

Larabee stood in the space between the Hyundai and the garage wall. Beside him was Joe Hawkins, an investigator with the MCME. On the floor between them was the metal death scene kit. Hawkins was shooting pics.

The driver’s door was open. Through it I could see Ajax slumped over the wheel, head twisted to the side, nasal mucus and saliva crusted on one cheek. His hands hung limp at his knees. A pair of tortoiseshell glasses lay on a mat by his feet. The macabre tableau brightened every time Hawkins’s flash went off.

“Doc.” Slidell’s way of announcing our arrival.

Larabee turned, thermometer in one gloved hand. Hawkins kept snapping away. “Detective Slidell. Dr. Brennan. Gotta love a brisk winter dawn.”

“What have we got?” Slidell opened his spiral.

“Probable carbon monoxide poisoning.”

“The guy offed himself?”

“The first responders found no signs of forced entry in the house or garage. No note. I’m seeing minimal trauma.”

“Minimal?”

“Abrasions on the forehead and right ear. Probably caused by the head impacting the wheel.”

“Probably?”

“Possibly.”

“Meaning suicide.”

“I’ll know after the autopsy.”

Most carbon monoxide deaths are due to accident or suicide. A few are due to foul play. Larabee knew and was being guarded.

“The garage door was down when Cauthern arrived?” Slidell asked.

“So I’m told.”

“The car hood wasn’t raised, right?”

“Right.”

“The vic have any grease on his hands?”

“No.”

Slidell scanned the small space where we stood. “No tools lying around.”

“I agree, Detective. This doesn’t look like an accident.”

“Time of death?”

“Based on body temp, I’d put it somewhere between twelve and two this morning. As usual, that’s only a rough estimate.”

“How long’s it take?”

“Death by carbon monoxide poisoning?”

Slidell nodded.

“Not long.”

Slidell frowned.

“It requires very little CO to produce lethal levels of carboxyhemoglobin in the body.”

The frown continued.

To his credit, Larabee showed no impatience. But he kept it simple. Very simple. “Carboxyhemoglobin disrupts oxygen supply to the cells.”

“Gimme a little more than that.”

“Okay.” Larabee did some editing. “Hemoglobin is a molecule found in the red blood cells. Its job is to circulate oxygen throughout the body. But hemoglobin has a strong affinity for carbon monoxide, CO. If both oxygen and carbon monoxide are present, hemoglobin is much more likely to bind with the CO. When that happens, you get carboxyhemoglobin, which can’t do the job.”

Larabee didn’t go into the fact that hemoglobin has four binding sites to maximize the capture of oxygen from arterial blood flowing from the lungs and to expedite its release into the tissues and organs. That in the presence of both oxygen and carbon monoxide, hemoglobin is two to three hundred times more likely to bind with the latter. That this binding with CO inhibits the release of O2 molecules found on the hemoglobin’s other binding sites. That, as a result, even if blood concentrations of oxygen rise, the O2 remains bound to the hemoglobin and isn’t delivered to the cells. That, as a consequence of oxygen deprivation, the heart goes into tachycardia, increasing the risk of angina, arrhythmia, and pulmonary edema. The brain short-circuits.

That carbon monoxide is very bad shit.

“We’re talking how much?” Slidell pressed.

“High blood levels of carboxyhemoglobin can result from air containing only small amounts of CO.”

“You breathe the stuff.”

“Yes.”

I was sure Slidell knew the basics, that he’d worked similar cases in the past. I wondered at his uncharacteristic interest in the physiology of carbon monoxide poisoning.

My brain fired a series of stats on CO blood levels. Of symptoms of toxicity. Bizarre. A stored holdover from some long-ago grad school course. 1 to 3 percent: normal. 7 to 10 percent: normal in smokers. 10 to 20 percent: headache, poor concentration. 30 to 40 percent: severe headache, nausea, vomiting, faintness, lethargy, elevated pulse and breathing rates. 40 to 60 percent: disorientation, weakness, loss of coordination. 60 percent: coma and death.

Slidell sighed. “How ’bout a ballpark?”

“Of?” Larabee had squatted to inspect Ajax’s hands.

“How long you last.”

“Inhaling air with a carbon monoxide level as low as point two percent can produce carboxyhemoglobin levels exceeding sixty percent in just thirty to forty-five minutes.”

“That’ll kill ya?”

“That’ll kill ya.”

Slidell jotted, then gestured with the spiral. “And we got that here?”

“Engine running in an enclosed one-car garage. Door lowered. Windows shut. Definitely.” Larabee spoke without looking up. “In as little as five to ten minutes.”

“So Ajax was toast soon after he turned the key.”

“Assuming he turned the key.”

“Assuming that.”

“And that he was breathing when he went into the car.”

“And that.”

“Which I suspect was the case. See this?” Larabee lifted one of Ajax’s hands.

Slidell eyeballed it from where he was standing. “That blood-settling thing. Because the arms are hanging down.”

“Yes. But I’m talking about the nail beds.”

Slidell bent for a closer look. “They’re bright pink.”

“Yes again. Which suggests he was alive.”

I pictured the cherry-red blood and organs Larabee would see when he made his Y incision. The slivers of liver, lung, stomach, kidney, heart, and spleen still cherry red when floating in formalin. Still cherry red when sliced into thin sections and placed on microscope slides.

“Remind me. When does the blood-settling thing start?”

“Livor. Within two hours of death. Peaks in six to eight.” Larabee stood. “But it’s cold out here. That would slow the process.”

“The livor in the fingers. That says no one moved the body, right?”

“Yes.”

“And he ain’t in rigor.” Slidell pronounced it “rigger.”

“There’s some stiffening in the smaller muscles of the face and neck. But that’s it.”

“Rigor starts when?”

“In roughly two hours. But low temperatures would slow that, too.” Larabee stood. “I’ll run a full tox screen.”

“Looking for what?”

“Whatever he had in him. People often self-medicate before killing themselves.”

“What’s the story in the house?”

“According to the first responders, the bed was made, the TV and radio were off, there was a single coffee cup in the sink, clean and upside down.”

“No note?”

“No note.”

“Nothing to suggest a visitor.”

“Not last I heard.”

“I’m done with my prelim.” Larabee turned to Hawkins. “Joe?”

Hawkins shot a couple more angles, the flash burning Ajax white-hot onto my retinas. Draped over the wheel, he looked like a man dozing, or drunk after a night on the town.

Slidell and I stepped outside. Hawkins positioned the gurney as close to the car as possible. Then he bent and grasped Ajax by the shoulders. Ajax slid free, lifeless and limp. Hawkins pinned the arms to his chest. Larabee caught the legs before the feet hit the ground. Together they transferred him to the body bag.

Flash recall. Maneuvering Pomerleau from her barrel in Vermont with Cheri Karras.

After collecting Ajax’s glasses and placing them by his head, Hawkins zipped the bag. Then he rolled the gurney to the van, loaded it, and slammed the doors.