Jason snatched at a lanyard hanging around his neck and grabbed a stopwatch, then punched a button. “Wow, that is right on time,” he said. He lurched out of the chair, hoisted the fire extinguisher, and discharged a cloud of vapor at the underside of the Lexus. Then he flung open the driver’s door, hopped in, and pulled the car forward about twenty feet.
When he did, he exposed a still-smoking circle of burned grass about two feet in diameter, along with a partially melted smoke detector lying near one edge and a pair of wires stretching to the thermocouple monitor now lying beside the chair. Jason shut off the car and clambered out, then gave the grass another shot with the extinguisher. He consulted the stopwatch dangling from his neck again. “Seven hours, forty-three minutes,” he said proudly.
I turned to Cash. “Seven hours, forty-three minutes. You think that gives your guy enough time to get to Las Vegas?”
“He flew direct on Allegiant,” Cash said. “Flight’s four hours and a quarter,” he said. “Thirty-minute drive to the airport; check-in and boarding takes another thirty, if you shave it close. I’d say it would.” He studied the charred circle, studied the Lexus, and then studied Jason.
“Okay, I give,” he said. “How’d you do it?”
“Take a look in the grass,” I said.
He squatted down beside the blackened circle, then dropped to one knee and leaned forward, almost like a football player on the line of scrimmage. He plucked something from the ground and held it up between his left thumb and forefinger. It was a piece of heavy steel wire, cinched tight around a ruffle of ragged plastic.
I nodded at it. “Recognize that?”
He scrutinized it. “It’s like the thing you found in the burned grass at the Latham farm,” he said, “but this plastic stuff is different.”
“Exactly,” I said. “It’s not melted. That’s because we put the fire out before the car burned.”
“I hate to say it, but you’ve still got me,” he said. “What is it?”
“That,” I said, “is the end of an eight-pound bag of ice.”
“A bag of ice?”
“A bag of ice,” I said. “I realized what it was the other night when I picked up a bag on the way to my son’s house. It’s how Latham delayed the fire. He dumped a bag of ice on the grass, drove the car so the catalytic converter was right over the ice, then skedaddled for the airport.”
He looked dubious. “Come on, Doc. How’s he gonna control that? How’s he gonna know it’ll work at all, and how’s he gonna know how much time it buys him?”
“You remember that smaller burned oval in the grass at the Lathams’ farm, the one near the barn?”
He nodded. “Actually,” he said, “we found two more of those after you pointed out the first one.”
I could see the light beginning to dawn. I pointed at the scorched grass, frosted with powder from the fire extinguisher.
“We’re not the only ones who do experiments. Stuart Latham might’ve made a good scientist.” I turned to Jason. “You want to summarize the data for Mr. Cash, Jason?”
Jason cleared his throat nervously. “Well,” he said, “we’ve only got six data points—actually, seven now—so statistically the data set isn’t robust. In fact, if you remove the two outliers—”
“Jason,” I interrupted, “just cut to the chase. Tell the man what you found.”
“Okay, sorry,” he said. “On average, it takes the ice about ninety minutes to melt, plus or minus ten percent, depending on how consolidated the ice remains and how close to the catalytic converter it is. But then the grass is wet and the ground’s cold, so it takes about another six hours for everything to dry out, and another fifteen minutes or so for the grass to reach its flash point and catch fire.”
“In the seven runs you’ve done,” I asked, “how much variation did you see in the total elapsed time between parking the car and seeing the grass catch fire?”
“Less than thirty minutes,” he said. “It’s surprisingly consistent. Now, if the grass were shorter or taller or a different type or—”
“Thank you, Jason,” I interrupted again. I regarded Cash.
“Does this look pretty similar to the grass in the pasture at the Latham farm?”
“If I were a cow,” he said, “I’d think I was eating at the same restaurant.”
“And you’ve got pictures of the Latham’s pasture, taken the day the car burned?”
“Sure,” he said. “Dozens.”
“Any good close-ups of unburned grass?”
“Well, we weren’t actually focusing on the grass as a murder weapon,” he said. “We took close-ups of the burned cigarette butts under the driver’s window, but the grass in that area was burned, obviously.” He frowned, then he brightened. “We do have wide shots that show the whole circle of burned grass, including the unburned grass around the edges. Come to think of it,” he added, “one of them shows a uniformed officer standing in the field. The grass comes up about yea high on him.” He bent down and sliced a hand across his lower leg, midway between the knee and the foot. As he did, the tops of the Ag field’s grass grazed his fingers.