IT IS COLD in the car, cold as the grave. I prefer to leave the a/c on full, to let the falling temperature keep me alert. The volume on the radio is low but I can still hear a tune, vaguely insistent over the sound of the engine. It’s early R.E.M., something about shoulders and rain. I’ve left Cornwall Bridge about eight miles behind and soon I’ll be entering South Canaan, then Canaan itself, before crossing the state line into Massachusetts. Ahead of me, the bright sun is fading as day bleeds slowly into night.

The patrol car arrived first on the night they died, shedding red light into the darkness. Two patrolmen entered the house, quickly yet cautiously, aware that they were responding to a call from one of their own, a policeman who had become a victim instead of the resort of victims.

I sat in the hallway with my head in my hands as they entered the kitchen of our Brooklyn home and glimpsed the remains of my wife and child. I watched as one conducted a brief search of the upstairs rooms while the other checked the living room, the dining room, all the time the kitchen calling them back, demanding that they bear witness.

I listened as they radioed for the Major Crime Scene Unit, informing them of a probable double homicide. I could hear the shock in their voices, yet they tried to communicate what they had seen as dispassionately as they could, like good cops should. Maybe, even then, they suspected me. They were policemen and they, more than anyone else, knew what people were capable of doing, even one of their own.