"Are they going to be okay?" I finally managed to ask.

"Yes," came the man's reply, "They are asleep."

With that, the man pulled from his holster a long black pistol. Momentarily distracted from his work, he spoke as if reading from a textbook or user manual. "The pistol has been specially modified to fire capsules made of an industrial poly-resin gelatine. The chemical inside is released upon impact, releasing a localized vapour which hyper-stimulates the thalamus and hypothalamus in a way which induces the target to sleep."

His sentence ended abruptly there, yet he continued to stare at me in silence. For an awkward moment he waited and, unable to read his expressionless visage, I was unaware of exactly what he was waiting for. Eventually I managed to stammer, "Ah.. I see. Very clever."

"Thank-you," came the disinterested reply.

Not wanting to lose the momentum, I managed to ask another question. "This man is the killer," I said, motioning towards the sleeping figure on the floor, "but who is the girl?"

"His victim. I put her to sleep as well. She was crying and screaming for some reason and I found it difficult to continue my investigation."

"Why didn't you release her? Console her?" I asked, "after what she saw..."

"Obviously," he interjected, "you wouldn't be here if you hadn't." Were his voice not so devoid of inflection, I would have sworn there was a snarkiness to his tone.

"May I ask why you... why you wanted me to be here? To see this?"

Sleepwalk turned and walked towards me. As he approached, I felt extremely uneasy, unsure of what he might do next. Extending his hand he held one of the photographs from the wall for me to see. It depicted a small boy, looking very glum, flanked on either side by a man and a woman. In the background a carnival, and in the boy's hand, a balloon. Most tellingly for me, as a profiler, the adults faces had been viciously scratched out of the photos.

"The photos were all developed on Fugachi F-500 photo paper," he noted, "this photograph appears to have been taken with an older model camera - possibly one of the Brownlevy Optima series, but I haven't established that conclusively yet. The others seem to have been taken with a later model."

With that, he quickly displayed the other photos. In them lay the whole of the killer's childhood - a successive series of photos depicting his life up into adulthood. In each instance, the faces of whom I assumed to be his parents were scratched out, leaving ominous holes where once their images resided.

"The angle of the pins indicate that the killer was left-handed, something I had already deduced from the wounds inflicted on his victim and than hand in which he held his cleaver," continued Sleepwalk, "Their placement on the wall seems roughly chronological and, given the spray pattern of the blood, appear to have been placed there at some point late in the attack on this victim. The scratching pattern seems to have been made with a sharp, metallic object - most likely a nail or perhaps a larger sized pin - based on the striation marks."

Another long awkward silence as he stood there, holding the photograph mere inches from my face. "Why am I here?" I finally asked quietly.

"The scratched out faces. Faces. Faces...", he said, repeating himself a few times before, through great effort, he forced himself to continue, "Why did the perpetrator scratch them out? Is he perhaps hiding the identities of accomplices?"

To most it would seem unfathomable. This man, so thorough and exacting in his observation of criminal activity and the collection of evidence, was unable to draw a conclusion any first year psychology student could make. I was not surprised, however. His actions only strengthened my confidence in the diagnosis I had made.

"Do you really not understand?" I asked, somewhat rhetorically, "the answer is as plain as the nose on your face."

Puzzled, Sleepwalk touched his nose for a moment. "I fail to see the relevance my nose has on this investigation."

Growing bolder, I took the picture from his hand and turned it to him. "The boy in this picture. Is he happy or sad?"

Sleepwalk studied the boy's frowning visage for a moment. "He is clearly at a fair or carnival of some sort, most likely with his parents. He has a balloon as well, and children like balloons. Therefore I would conclude that he is happy."

"He's not happy," I informed him, "he is sad � troubled � and he has scratched out the faces of his parents because he hates them. I would guess that part of why he kills people is to act out that displaced rage."

Sleepwalk thought for moment on what I had said, but I could tell he still didn't understand. "Asperger's syndrome," I continued, "a form of autism characterized by a hyper-intense focus on areas of interest, an inability to recognize emotional states and facial expressions, literal interpretation of expressions, poor handwriting, formalized repetitive speech patterns, social impairment...but also vast increases in memory, logical reasoning and mental focus."

"I have had ... difficulty... in my investigations," he eventually admitted, "I am quite gifted in many areas � observing clues at a scene, deducing logical patterns, recalling minute details � but my condition poses many unique challenges."

"Motive," I said conclusively, "You observe crime and criminals. Your condition compels you to investigate and document them obsessively. Still, however, it prevents you from understanding why. What drives men to commit these acts? Hate. Jealousy. Love. You can't see that in their eyes like the rest of us can. They don't fit into the logical structures you create to try to explain or understand how this all happens."

Sleepwalk finished his writing and placed the book inside the box before sealing it. "I want you to help me Doctor," he said quietly as he rose from the floor, "I am, as I had indicated, not good with people. Dealing with people. Understanding people. Without your help, my investigations are incomplete � imperfect. I find this... unsettling."

"I will do what I can," came my reply, "how will I contact you?"

"You won't," he said, dropping two black metallic spheres from his left hand. A thick grey smoke quickly filled the room, causing me to fight for air in the sudden inky haze. As quickly as it appeared, the smoke receded, and once it has dissipated I could see that Sleepwalk was gone.