‘You didn’t know, did you.

‘It took me longer than I thought it would to find Sven Sivertsen,’ Wilhelm said. ‘I made a copy of the photo Lisbeth was sent and travelled to Prague. I trawled through the cafes and bars in Mustek and Perlova showing the photo and asking if anyone knew a Norwegian called Sven Sivertsen. Nothing. But it was obvious that some of them knew more than they were willing to divulge. So, after a few days I changed my tactics. I began to ask if there was someone who could procure some red diamonds for me. I knew that it was possible to get hold of some in Prague. I took on the identity of a Danish diamond collector by the name of Peter Sandmann and I made it apparent that I was prepared to pay very well for a special diamond that had been cut into the shape of a five-pointed star. I said where I was staying and after two days the telephone in my room rang. I knew it was him as soon as I heard the voice. I disguised my voice and spoke in English. I told him I was in the middle of negotiations for another diamond and asked if I could phone him later that evening. Did he have a number where I could be sure to get hold of him? I could hear how he was trying not to sound keen and thought how easy it would be to meet him in some dark back street that evening. I controlled myself, though, like the hunter who has to control himself when he has the prey in his sights, but must still wait until everything is perfect. Do you understand?’

Harry nodded slowly. ‘I understand.’

‘He gave me his mobile phone number. The next day I returned to Oslo. It took me a week to find out what I needed about Sven Sivertsen. Identifying him was the easiest. There were twenty-nine Sven Sivertsens on the national register, nine of them the right age and only one without fixed residence in Norway. I noted down his last known address, got the telephone number from directory enquiries and rang.

‘An old lady answered the phone. She said that Sven was her son, but that he hadn’t lived at home for many years. I told her that myself and a couple of others from his old school class were trying to get everyone together for an anniversary reunion. She said he lived in Prague, but that he travelled a lot and didn’t have a fixed address or telephone number. On top of which, she said, he wouldn’t be very interested in meeting any of his old classmates. What did I say my name was? I said that I’d only been in his class for six months, so it was doubtful whether he would remember my name. And if he did, it was probably because I’d landed myself in a spot of bother with the police at the time. Was the rumour true that Sven had, too? His mother’s tone became a bit sharp then and she said it was all a long time ago, and it was not so strange that Sven became a bit rebellious, considering the way we treated him. I apologised on behalf of the class, put down the phone and called the Law Courts. I said I was a journalist and asked if they could tell me what sentences Sven Sivertsen had received. An hour later I had a pretty good idea what he was up to in Prague. Smuggling diamonds and weapons. A plan began to take shape in my mind, based on what I now knew: that he made his money through smuggling; the five-pointed diamonds; weapons; his mother’s address. Do you begin to see the links now?’

Harry didn’t answer.

‘When next I rang Sven Sivertsen, three weeks had gone by since my trip to Prague. I spoke Norwegian in my normal voice, went straight to the point and told him that I’d been looking for someone to procure weapons and diamonds for me for a long time and I didn’t want any middle-men involved. I said I thought I had found someone: him, Sven Sivertsen. He asked me how I’d got hold of his name and number and I answered that my discretion could also benefit him. I suggested that we didn’t ask each other any further unnecessary questions. That wasn’t particularly well received and the conversation almost came to a halt there and then. Until I mentioned the sum of money I was willing to pay for the goods, up front and into a Swiss bank account if required. We even had the classic film dialogue where he asked me if I meant kroner and I answered in a somewhat surprised tone that of course we were talking euros. I knew that the sum of money alone would dispel any lingering suspicion that I might be a policeman. You don’t need an almighty sledgehammer to crack a nut like Sivertsen. He said everything could be arranged. I said I’d get back to him presently.

‘So while the rehearsals for My Fair Lady were in full swing, I put the finishing touches to my plan. Will that do, Harry?’

Harry shook his head. The sound of the shower. How long was she planning to stay in there?

‘I want details.’

‘They’re mostly technical things,’ Wilhelm said. ‘Aren’t they tedious?’

‘Not to me.’

‘Very well. The first thing I had to do was to give Sven Sivertsen a personality. The most important thing you have to do when unveiling a character to an audience is to show what motivates the person, what the character’s innermost wishes and dreams are: in a nutshell, what makes this person tick. I decided that I would present him as a murderer without any rational motive, but with a sexual need for ritual killings. A little commonplace maybe, but the vital ingredient was that all the victims except Sivertsen’s mother had to appear to have been chosen at random. I read up about serial killers and found a couple of amusing details I elected to use. For example, the stuff about mother fixation and Jack the Ripper’s choice of murder locations, which investigators took to be a code. So I went to the City Planning Department where I bought a detailed map of Oslo city centre. When I returned home I drew a line from our own apartment building in Sannergata to the house where Sven Sivertsen’s mother lives. From this one line I then drew a precise pentagram and found the addresses closest to the tips of the other star points. And I admit that it did give me an adrenalin rush when I put the point of the pencil down on the map and I knew that there – right there – lived someone whose fate had just been sealed that very second.

‘For the first few nights I fantasised about who it could be, what they might look like and how their lives had been so far. I soon forgot them though. They weren’t important – they were the scenery, the extras, the non-speaking parts.’

‘Building materials.’

‘Pardon?’

‘Nothing. Go on.’

‘I knew that the blood diamonds and the murder weapons would be traced back to Sven Sivertsen when he’d been arrested. To strengthen the illusion of ritual deaths I threw in a few clues: the severed fingers, five days between each murder, five o’clock and the fifth floor.’

Wilhelm smiled.

‘I didn’t want to make it too easy, but not too difficult either. And I wanted a little humour. Good tragedies always have a little humour, Harry.’

Harry told himself to sit completely still.

‘You received the first gun a few days before you killed Marius Veland. Is that right?’

‘Yes. The gun was in the litter bin in Frogner Park, as arranged.’

Harry took a deep breath: ‘And how was that, Wilhelm? What was it like to kill?’

Wilhelm pressed his lower lip forward and appeared to be considering the question.

‘They’re right, the people who say the first time is the most difficult. I slipped into the student block without a problem, but it took much more time than I had ever imagined to seal the rubber bag I put him in with the heat gun. And despite having spent half of my life lifting up well-nourished Norwegian ballerinas, it was a tough job carrying the boy up into the loft.’

Pause. Harry cleared his throat.

‘And afterwards?’

‘Afterwards I cycled to Frogner Park to pick up the second gun and the diamond. The German half-breed Sven Sivertsen proved to be as punctual and greedy as I’d hoped. The technique of placing him in Frogner Park at the time every murder was committed was a good touch, don’t you think? After all, he was committing a crime himself, so he would take care not to be recognised and make sure no-one knew where he’d been. I simply made sure that he would not have an alibi.’