Sandra only knows that we may have a coded message in this magazine. To be honest, that’s all she’s interested in.’
‘And did she find anything?’ asked Vestergaard.
‘It took her five minutes to find the message and crack the code. No more.’
‘Are you trying to tell me that an amateur cryptologist can break a code created by one of the world’s most successful secret police and espionage agencies?’ Fabel smiled patronisingly.
Kraus drummed her fingers on the table again, took a sip of her coffee and then spoke briskly. ‘I have advantages that they didn’t have. I have an inbuilt ability to recognise patterns in things. What you see as complexity, I see as structure and ultimately simplicity.’
‘There’s more,’ said Anna. ‘I got all of the issues of Muliebritas for the last three years. Drescher was using it regularly to communicate with the Valkyrie. Sandra has decoded dozens of messages.’
‘It really wasn’t that difficult. The person who called himself “Uncle Georg” in the announcements used a combination of polyalphabetic cyphers. Basically he used a Vigenere Square with a staggered shift of Caesar cyphers. Basic stuff. For example…’
She took a pad and pencil out of the huge shoulder bag and wrote ALTONABALKONSFOURTHIRTYPMTHURSDAY on the pad. Fabel noticed that Kraus’s handwriting was perfect, the capital letters corresponded exactly with the lines on the pad.
‘That becomes VLEYLRJEGKZXQWWYMTSSPKGTHT-SEPJLET,’ she continued. ‘Of course, a long jumble of letters like that would be very easily noticed by anyone looking at the magazine, and would attract the attention of any cryptologist, so he buried them in several personal ads throughout the announcements section. He put in thanks notices that listed names. The initials would give several of the encrypted letters in each announcement.’
‘And you’re absolutely positive that you have interpreted the codes correctly?’ asked Fabel.
‘Like I said, it was a simple enough encryption. In principle. But for three hundred years the Vigenere cypher was considered unbreakable simply because to decode the encryption you have to know which word was used as the keyword. In other words, what the vertical letters are on the axis of the Vigenere Square.’
‘And you worked it out?’ asked Fabel. ‘How?’
‘I just saw it. I have this knack for frequency analysis of letters and recognition of common pairings. I read all the messages and I could see the patterns. You’re only supposed to be able to do frequency analysis with monoalphabetic cyphers; not with a polyalphabetic cypher like this one where an encrypted letter can be decoded as more than one original.’
‘But Sandra can do it,’ said Anna with clear pride in her friend’s abilities. ‘Tell him the keyword, Sandra.’
‘Valkyrie,’ said Kraus, again drumming out the same tattoo with her fingertips on the tabletop. ‘The word used as the keyword was Valkyrie.’
As Anna drove back to the Presidium, Fabel sat in the passenger seat and went through the messages Sandra Kraus had decoded.
‘These are all times and places,’ said Fabel over his shoulder to Vestergaard, who sat in the back. ‘Obviously he passed anything sensitive on in person. This was just used to set up a meeting.’
‘So that means we can now do exactly the same,’ said Vestergaard. ‘We can lure this Valkyrie out into the open. Assuming she really doesn’t know about Drescher’s death.’
‘We’ve still got the lid tight on that, but for how much longer I don’t know.’ Fabel turned to Anna. ‘That’s an interesting friend you’ve got there.’
‘Sandra? She’s great. She has a genius IQ.’
‘I guessed that much,’ Fabel said, with a small laugh.
‘And she’s an Aspie.’
‘A what?’
‘Did you notice her drumming her fingers all the time? Same rhythm, same number of beats. Or how she’s got an unnerving way of seeking eye contact with you?’
‘As a matter of fact I did,’ said Fabel.
‘Sandra has Asperger’s syndrome. But she calls herself an Aspie. She doesn’t see herself as a sufferer from a disability. Just different, and she’s cool with that. She campaigns for a group that promotes neurodiversity… the idea that there is more than one type of mind. She calls us NTs — Neurologically Typical.’
‘I thought people with Asperger’s have difficulty with interpersonal relationships. You said she’s your friend…’ said Vestergaard from the back seat.
‘A good friend,’ said Anna. ‘Sandra has problems in some areas, but, as you could see, there are compensations in others. And she has taught herself coping strategies and stuff. I’ve learned not to judge. It’s funny: Sandra said that one of the stereotypes people have of Aspies is that they have little or no empathy for the feelings of others. That’s why it’s often difficult to recognise a male Aspie: who can tell the difference from a normal man?’
Vestergaard gave a loud laugh. Fabel shrugged.
‘Well, one thing’s for sure,’ he said. ‘Your friend Sandra has probably given us our biggest break in this case so far.’
The preliminary forensics survey of Sparwald’s house had, as expected, surrendered nothing much. Fabel was surprised, however, at just how much Astrid Bremer had been able to read from such meagre trace evidence. She was still at Poppenbuttel when she phoned him at his office in the Presidium.
‘I’ve had the body removed and we’ll get the autopsy report, obviously. But my guess is that the victim was dead before he hit the floor. The killer put another bullet in him, firing along the victim’s already supine body and causing an entry wound under his chin. Very professional job. The last shot was probably insurance. Professional meticulousness.’
‘There was a similar murder outside Oslo,’ said Fabel. ‘Exactly the same modus.’
‘My guess is that the victim didn’t let the killer into the house. There was a book beside him on the floor. No prints other than his own and it’s obvious he dropped it when he was shot. And I found powder traces on the wall by the lounge door and on the edge of the door itself. Again no prints on the door handle or anywhere else that I could see. I’m guessing that the killer opened the lounge door, stepped in and fired before the victim had time to respond. The killer didn’t need to go any further into the room, so she retraced her steps back along the hall to the front door. It was a hunch, but I was right: there is no evidence of the door having been forced, but there is some fresh scratching around the lock. She picked it.’
‘But nothing we can get DNA from? Or any trace of any kind?’ Fabel failed to conceal his frustration.
‘A faint partial bootprint in the hall, bearing traces of soil from the garden, but that could have been anyone’s and made at any time. And, anyway, it’s not big enough to give us a match.’
‘Great,’ said Fabel.
‘Sorry. I did my best,’ said Astrid and, even over the phone, Fabel could tell that she meant it. ‘I went over everything three times. Tried all the tricks. There just wasn’t anything to find.’
‘It’s not your fault. Holger told me that if anyone could get something, you could. He also said you’re the best he’s worked with for cold scenes.’
‘Thanks,’ Astrid said. ‘But whoever killed Sparwald is better.’
After he’d hung up Fabel made his way into the main Murder Commission meeting room. Werner, Anna, Henk and Dirk were waiting for him. He had also invited Karin Vestergaard to join them, but she had phoned in to say she’d be a few minutes late.
‘You know,’ said Werner, ‘if we’re looking for a Valkyrie, we couldn’t go far wrong looking at the Danish ice maiden. She’s a cold one all right.’
‘She’s a good cop, from what I can see,’ said Fabel.
‘Listen,’ said Anna, ‘while we’re on the subject of people we should be thinking about… I’m not being funny, but there are two women we should maybe take a long hard look at. Martina Schilmann and Petra Meissner.’
‘Why Martina?’ Fabel searched Anna’s face for meaning. ‘She’s ex-Polizei Hamburg, for God’s sake.’
‘She was also involved with Westland and was there at the scene. Let’s face it, we’ve only got her word that she was at the opposite end of Herbertstrasse all the time she said she was. And she was brought up in the GDR, as was Petra Meissner. Both fall within the age range we have for the Valkyrie.’
‘What?’ said Fabel dismissively. ‘So now we’re going to suspect all women from East Germany? We’d better bring in Chancellor Merkel, then. She was brought up in Brandenburg, after all.’ Fabel sarcastically put on an
