And was rewarded with the sight of the man himself, walking his dog.

Keller came up on them from the rear, and the man could have been anybody dressed for a day at the office, but the dog was unmistakably a golden retriever.

Keller had owned a dog for a while, an Australian cattle dog named Nelson. Nelson was long gone-the young woman whose job it was to walk him had, ultimately, walked off with him-and Keller had no intention of replacing either of them. But he was still a dog person. When February rolled around, he watched the American Kennel Club show on television, and figured one of these years he’d go over to Madison Square Garden and see it in person. He knew the different breeds, but even if he didn’t, well, how tough was it to recognize a golden retriever?

Of course, a street like Winding Acres Drive could support more than one golden retriever. The breed, oafishly endearing and good with children, was deservedly popular, especially in suburban neighborhoods with large homes on ample lots. So just because this particular dog was a golden didn’t mean it was necessarily Powhatan.

All this was going through Keller’s mind even as he was overtaking man and dog from the rear. He passed them, and one glance as he did so was all it took. That was the man in the photograph, walking the dog in the photograph.

Keller circled the block, and so, eventually, did the man and the dog. Keller, parked a few houses away on the other side of the street, watched them head up the walk to the front door. Hirschhorn unlocked the door and let the dog in. He stayed outside himself, and a moment later he was joined by his children.

Jason and Tamara. Keller was too far away to recognize them, but he could put two and two together as well as the next man. The man and two children went to the garage, entering through the side door, and Keller keyed the ignition and timed things so that he passed the Hirschhorn driveway just as the garage door went up. There were two cars in the two-and-a-half-car garage, one a squareback sedan he couldn’t identify and the other a Jeep Cherokee.