“That’s what I’m thinking. When you want a big transport vehicle that you use as a mobile office and command post it’s always going to be forty-four-ten.” He refers to the last four numbers of the truck’s license tag. “Assuming it’s available for deployment and in good repair with plenty of gas. Anyone who knows much about you knows that your first choice is forty-four-ten if you’re driving yourself to a complicated scene.”

“And I specifically requested this truck this morning because I knew Chanel Gilbert would be an involved time-consuming case. Even if it was nothing more than a random accident we have a bloody scene with a lot of questions. We have a high-profile victim and a high-profile neighborhood in Cambridge. We have potential political complications.”

“It was a safe bet that this was the vehicle to tamper with,” Marino says, and I step closer to him.

I’m up to my bootlaces in a puddle as I examine the rectangular outline on the white metal chassis where the mount was attached. I look at the hole with the plastic-coated wires threaded through it, and he’s right. The arrow would have fit with room to spare.

“If this is the point of entry and I believe it is,” I decide, “that’s important because it suggests that whoever is responsible …”

“We know who.” Marino blurts it out. “Why not just act like we know it’s her. Who else would it be?”

“I’m trying to be objective.”

“Don’t bother.”

“What I was about to say is she didn’t necessarily access the inside of the truck. So she didn’t need a key.”

“Exactly. What she did was remove the lens and the entire housing, exposing the hole in the cab and the grommet the wiring runs through,” he explains. “Now you have a breach, a way to get something inside the truck without opening it up. That made it a cinch when it was time to drop the arrow in. All she had to do was move the housing, swivel it to one side until the hole was exposed, drop the arrow in and straighten the mount again.” He demonstrates. “It would take all of three seconds.”

“And this was done while we were parked on Lucy’s driveway.”

“I’m thinking the taillight was sabotaged earlier, maybe when the truck was in the CFC parking lot. But I doubt the arrow was put in there at the same time or we would have heard it rolling around. We’ve been riding in this damn thing since we met at your office early this morning. We didn’t hear anything clanking until we were headed back here a few minutes ago.”

“You want to package this now?” I ask.