“The trick is to cut a little notch right here,” he shows Mahant, who isn’t blinking and hardly breathing anymore. “Then I insert the chisel and give it a little quick turn like a skate key.” Harold does it as he talks, and then he’s catching the ASAC as he topples like a tree to the tile floor.

“Oh dear. Let’s get him some air.” Harold holds him up and walks him to the door, and he’s done this quite a lot in his career. “Here.” He opens it and leads him out. “Let’s find you a chair,” he says in his best funeral-director voice. “Can one of you gentlemen please find a chair? He just needs a little air,” he says to the agents in the corridor, and I must be a bad person.

I stay inside the decomp room and do nothing to help Mahant. As long as he doesn’t throw up on the body or crack his head on the floor, I don’t care if he’s faint or queasy. I pretend I do but I know it’s not true, and maybe he and his merry band of agents will leave and not come back.

“Take a look.” Luke is slicing the heart on the cutting board.

He uses a towel to pat dry a section, and the fresh myocardial contusion is a tiny bluish-black spot on the pale heart muscle.

“Basically the electrical current walloped her heart and stopped it,” he says.

“Do you think the injury to her head would have knocked her out?” Anne asks. “On CT she definitely has subarachnoid hemorrhage.”

“It might have,” I reply, “but it doesn’t matter because the head injury didn’t contribute to her death. Maybe it would have but there wasn’t a chance. She was already dying when she hit the ground.”

“Taking everything into account?” Luke adds as he takes photographs. “Death resulted from respiratory arrest due to electrocution. She probably didn’t survive longer than several minutes, and I doubt she knew what hit her.”

CHAPTER 42

ACROSS THE RIVER THE rooftops of Boston are a gray dragon’s back of slate tiles and chimney pots. I watch the darkness lifting on the horizon, the sun rising before my eyes.

From my office with a view I witness dawn touch the new day, the river turning variegated shades of blue with greenish hues. Iron lamps blink off along the pale gash of the fitness path where people are out riding bikes and jogging. The world is waking up as usual, as if nothing at all happened last night not even a mile downriver from here. The death in John F. Kennedy Park has hit the news but you’d never know it to look out my windows.