"Mark's got the same kind of problem," I said. "Mel says she was with him, but she's his girlfriend, and they're not much more reliable than mothers. A little, but not much. So here we all are."

"And if you've got anything to tell us, Damien," Cassie said softly, "now's the time."

Silence. He took a sip of his 7-Up and then looked up at us, all transparent blue eyes and bewilderment, and shook his head.

"OK," I said. "Fair enough. There's something I want you to look at, Damien." I went through the file, making kind of a big deal of it-Damien's eyes followed my hand, apprehensively-and finally pulled out a bunch of photos. I laid them out in front of him, one by one, taking a good look at each before I put it down; letting him wait.

"Katy and her sisters, last Christmas," I said. Plastic tree, garish with red and green lights; Rosalind in the middle, wearing blue velvet and giving the camera an impish little smile, her arms around the twins; Katy straight-backed and laughing, waving a white fake-sheepskin jacket, and Jessica smiling uncertainly down at a beige one, like a reflection in some uncanny mirror. Unconsciously, Damien smiled back.

"Katy at a family picnic, two months ago." The snapshot with the green lawn and the sandwich.

"She looks happy, doesn't she?" Cassie said, aside to me. "She was about to go off to ballet school, everything was just beginning… It's good to know she was happy, before…"

One of the crime scene Polaroids: a full-length shot of her curled on the altar stone. "Katy just after you found her. Remember that?" Damien shifted in his chair, caught himself and sat still.

Another crime-scene shot, this one a close-up: dried blood on her nose and mouth, that one eye a slit open. "Same again: Katy where her killer dumped her."

One of the post-mortem shots: "Katy the next day." The breath went out of Damien. We had chosen the nastiest picture we had: her face folded down on itself to reveal the skull, a gloved hand holding up a steel ruler to the fracture above her ear, clotted hair and splinters of bone.

"Hard to look at, isn't it?" Cassie said, almost to herself. Her fingers hovered over the photos, moved to the crime-scene close-up, stroked the line of Katy's cheek. She glanced up, at Damien.

"Yeah," he whispered.

"See, to me," I said, leaning back in my chair and tapping the post-mortem shot, "that looks like something that only a raving psycho would do to a little girl. Some animal with no conscience, who gets his kicks out of hurting the most vulnerable people he can find. But I'm just a detective. Now Detective Maddox here, she's studied psychology. Do you know what a profiler is, Damien?"

A tiny shake of the head. His eyes were still riveted to the photographs, but I didn't think he was seeing them.

"Someone who studies what kind of person commits what kind of crime, tells the police what type of guy to look for. Detective Maddox, she's our resident profiler, and she's got her own theory about the guy who did this."

"Damien," Cassie said, "let me tell you something. I've said all along, right from day one, that this was done by someone who didn't want to do it. Someone who wasn't violent, wasn't a killer, didn't enjoy causing pain; someone who did this because he had to. He didn't have any choice. That's what I've been saying since the day we got this case."

"It's true, she has," I said. "The rest of us said she was off her head, but she stuck to her guns: this wasn't a psycho, or a serial killer, or a child-rapist." Damien flinched, a quick jerk of the chin. "What do you think, Damien? Do you think it takes a sick bastard to do something like this, or do you think this could just happen to a normal guy who never wanted to hurt anyone?"

He tried to shrug, but his shoulders were too tense and it came out as a grotesque twitch. I got up and wandered around the table, taking my time, to lean against the wall behind him. "Well, we'll never know for sure one way or the other, unless he tells us. But let's just say for a moment that Detective Maddox is right. I mean, she's the one with the psychology training; I'm willing to admit she could have a point. Let's say this guy isn't the violent type; he was never meant to be a murderer. It just happened."

Damien had been holding his breath. He let it out, caught it again with a little gasp.

"I've seen guys like that before. Do you know what happens to them, afterwards? They go to fucking pieces, Damien. They can't live with themselves. We've seen it, over and over."

"It's not pretty," Cassie said softly. "We know what happened, the guy knows we know, but he's scared to confess. He thinks going to jail is the worst thing that could happen to him. God, is he ever wrong. Every day, for the rest of his life, he wakes up in the morning and it hits him all over again, like it was yesterday. Every night he's scared to go to sleep because of the nightmares. He keeps thinking it has to get better, but it never does."

"And sooner or later," I said, from the shadows behind him, "he has a nervous breakdown, and he ends up spending the next few years in a padded cell, wearing pajamas and drugged up to the eyeballs. Or he ties a rope to the banisters one evening and hangs himself. More often than you'd think, Damien, they just can't face another day."

This was bullshit, by the way; of course it was. Of those dozen un-charged murderers I could name for you, only one killed himself, and he had a history of untreated mental problems to start with. The rest are living more or less exactly as they always did, holding down jobs and going to the pub and taking their kids to the zoo, and if they occasionally get the heebie-jeebies they keep it to themselves. Human beings, as I know better than most, can get used to anything. Over time, even the unthinkable gradually wears a little niche for itself in your mind and becomes just something that happened. But Katy had only been dead a month, and Damien hadn't had time to learn this. He was rigid in his chair, staring down at his 7-Up and breathing as if it hurt.

"You know which ones survive, Damien?" Cassie asked. She leaned across the table and laid her fingertips on his arm. "The ones who confess. The ones who do their time. Seven years later, or whatever, it's over; they get out of jail and they can start again. They don't have to see their victims' faces every time they close their eyes. They don't have to spend every second of every day terrified that this is the day they're going to be caught. They don't have to jump a mile every time they see a cop or there's a knock at the door. Believe me: in the long run, those are the ones who get away."

He was squeezing the can so hard that it buckled, with a sharp little crack. We all jumped.

"Damien," I asked, very quietly, "does any of this sound familiar?"

And, at long last, there it was: that tiny dissolution in the back of his neck, the sway of his head as his spine crumpled. Almost imperceptibly, after what seemed like an age, he nodded.

"Do you want to live like this for the rest of your life?"

His head moved, unevenly, from side to side.

Cassie gave his arm one last little pat and took her hand away: nothing that could look like coercion. "You didn't want to kill Katy, did you?" she said; gently, so gently, her voice falling soft as snow over the room. "It just happened."

"Yeah." He whispered it, barely a breath, but I heard. I was listening so hard I could almost hear his heart beating. "It just happened."

For a moment the room seemed to fold in on itself, as if some explosion too enormous to be heard had sucked all the air away. None of us could move. Damien's hands had gone limp around the can; it dropped to the table with a clunk, rocked crazily, came to a stop. The overhead light streaked his curls with hazy bronze. Then the room breathed in again, a slow, replete sigh.