I had arranged an interview with the new Professor, planning to write an article for the campus newsletter. I arrived at his office a few minutes early, and was immediately ushered inside. He stood up in a quaintly old-fashioned way when I entered the room and walked around the desk to shake my hand, smiling broadly. He gestured in the direction of a comfortable chair before returning to his own seat and toying with a pencil.

The Professor was a broad-shouldered man of middle years and looked as if he had kept himself very much in shape. His hair was full and wavy, with the merest flecks of grey at the temples. He was dressed very casually in neatly pressed blue jeans and a polo shirt. Taking a notepad out of my handbag, I asked whether he was ready to proceed with the interview. He nodded calmly in response, fixing me with an alarmingly direct stare.

His first few answers to my prepared questions were bland enough, and I began to wonder if I could make any kind of journalistic story from the few notes I was able to take. But then, I asked how he had become interested in forensics. The Professor stared into the middle distance for a few moments, looking thoughtful while tapping his pencil absent-mindedly against a glass jar containing some grey powder that stood on his desk.

"Well," he said eventually, "That is a tale. Are you interested?"

I nodded, already half captivated by those charming blue eyes.

"Let me take you back to the 1970s, then," he continued candidly, looking openly at me, "To when I was a student, a postgraduate in this very University."

*

I had just moved into a shared house with a number of other postgraduates, none of which I knew at all. As was commonplace at that time, the landlord rented individual bed-sitting rooms to impoverished students and provided the shared use of kitchen, bathroom and toilet.

I had managed to obtain the use of a room at the top of the house - almost a garret, really - but it suited me well enough. It was quite large, draft-free and surprisingly warm; maybe the roof was quite well insulated - at least by the standards of the time - or perhaps because the heat from elsewhere in the house tended to gather in the upper floors.

On the down side, the space was rather dark, being lit only by a couple of small angled windows, almost like a turret set into the corner of the room, and a single 60-watt light bulb in a faintly grubby glass lamp shade set in the middle of the ceiling.

Upon my arrival, I had installed my meagre possessions: a few clothes packed in a tatty old suitcase, quite a few books, a box of assorted tools, a bicycle and a substantial collection of radio and electronic items my Mother had long since classified as "junk". In point of fact, a fair bit of it actually worked, although even more was in the process of being repaired, modified or rebuilt. Yet other items were being dismantled for spare parts, or horded ready to be swapped or traded with my acquaintances at the University Amateur Radio Club.

One of my first tasks was to set up some of my equipment on the rickety table my landlord had described as a desk. The two-way VHF radio equipment was the first item on the agenda. As a rather shy, perhaps introverted young man, this gave me an unthreatening way of keeping in touch with my few - nerdy, we would say nowadays - friends. The transceiver itself I had bought a year or so before with money from my student grant I could not really afford, the power supply I had assembled myself, and the antenna I had made from a length of 300-ohm flat cable.

The homebrew aerial I had initially hung from the picture rail on the bed-sit wall. This worked reasonably well, being high up in the building after all, but I convinced myself that it would be even better if it was sited even higher up. So I decided to install it in the attic.

Admission to the roof-space was via a ceiling hatchway I had spotted in the hall immediately on my arrival, just outside my bedroom door. It was quite difficult to access the loft: there were no stairs or pull-down ladder. In order for me to get up there, it was necessary to drag the upright chair from my room and balance precariously on the back, then pull myself up, holding a torch in my teeth. As it turned out, the torch was unnecessary, since there was a light switch screwed to a beam just inside the opening.

My plan was to install a slim cable for the aerial, using a hole I had drilled in the plasterboard in an inconspicuous corner of the ceiling, where I hoped it would not be noticed by the landlord on his - hopefully very infrequent - inspection visits. The cable run was to be concealed by a large free-standing wardrobe and the old battered suitcase I had placed on top of it.

The loft space itself was floor-boarded over, so there was no risk of slipping between the joists and putting my foot through the ceiling. There was no natural light except that which seeped through the gaps between the roof tiles, but I could see well enough by the illumination provided by a weak and unshaded bulb.

As I looked around, it rapidly became clear that someone had been living in this attic. A narrow mattress had been placed on the boards, with a plain but serviceable sleeping bag folded neatly upon it. Beside this makeshift bed stood a suitcase so scuffed and decrepit, it made my own luggage look positively resplendent by comparison.

Overcome with curiosity, I opened the case, which turned out to be half-filled with sweatshirts and jeans which could have been worn, in that era, by anybody - girl or boy - under the age of twenty-two.

It seemed to me as if someone had slept there only last night: as far as I could see, no dust had settled on the mattress and sleeping bag, and the clothes in the suitcase, although clearly not new, were clean and well-laundered.

Of course, student accommodation was always a problem for the impecunious students themselves. For example, in the University Department where I was studying, I had already come to suspect that some people really were living full-time, unofficially, in the laboratories and offices.

I remember a clique of students from the People's Republic of China. Although their tuition fees to the University were paid by the British Council, the pittance that they had to live on - either from their families or their government, I was not sure which - meant that they really did have nowhere else to stay. They certainly always seemed to be around in the buildings at every time of the day or night. There were a number of other tell-tale signs, too: the persistent smell of cooking rice in one or two corridors, and sleeping bags stowed inconspicuously under the laboratory benches.

So it was not inconceivable that someone in the household had installed a friend in the building, without wanting the landlord to know about it and come around for extra rent money.

But, why live in the attic? Why not just share a room with someone officially resident? All of the rooms were quite large - the building had at one time been a spacious Edwardian semi-detached residence - and it seemed to me to be quite feasible to share the accommodation at the "kipping on the sofa" level, or just a sleeping bag on the floor.

Indeed, over the years I had been a student, I had hosted occasional visits from old friends from my single-sex Grammar school. These young men were now either studying at different universities or starting a career as bankers or chemical engineers. These chums would visit for the weekend, usually arriving carrying a rucksack and sleeping for a night or two on the floor of whatever room I happened to be occupying at the time.

So, was there someone living up there? In principle, the attic was potentially accessible to anyone in the house. Thinking back over the last few weeks when I had been resident, sometimes I thought I could hear noises outside my door, but there was never anyone there when I went to investigate.

Introduction Part 2