THE HARDEST MYSTERIES to solve are the ones you come to near the end, because there isn't enough evidence, not enough to unravel, unless somehow you can go all the way back to the beginning-rewind and replay everything.

    I was riding in the lap of comfort and civility, my year-old Mercedes. I was thinking about how odd it was to be going to a murder scene now. And then I was there, leaving my vehicle, and feeling conflicted about going over to the dark side again.

    Was I getting too soft for this? I wondered for an instant, then let it go. I wasn't soft. If anything, I was still too hard, too unyielding, too uncompromising.

    Then I was thinking that there was something particularly terrifying about random, senseless murder, and that's what this appeared to be, that's what everyone thought anyway. It’s what I was told when the call came to the house.

    “It's rough in there, Dr. Cross. Five vics. It's an entire family.”

    “Yeah, I know it is. That's what they said.”

    One of the first responders, a young officer I know named Michael Fescoe, met me on the sidewalk at the murder scene in Georgetown, not far from the university where I'd gone as an undergrad and which I remembered fondly for all sorts of reasons, but mostly because Georgetown had taken a chance on me,

    The patrolman was visibly shaken. No surprise there. Metro didn't call me in special at eleven o'clock on a Sunday night for run-of-the-mill homicides.