Ian Hocking - Déjà Vu

…in Cologne.

Besson opened his clamshell computer. The heat of his fingertips summoned a keyboard, red-glowing, as Jago, Saskia and Garland watched a projection on the wall. One pane showed a taxi against the frontage of the Park View Hotel. The other was crowded with a set of image processing tools.

‘I’ll say this for you,’ murmured Jago. ‘You’re well connected.’

‘I am,’ Saskia replied. ‘Paul, go.’

They watched the video from beginning to end. The story was simple: a car drove in from left of frame and stopped; Proctor opened the door, hesitated, then closed it. The windows remained opaque with reflected sky. Five minutes later, he opened the door a second time and walked out of the frame. The taxi drove away. For a period during those five minutes, he had made the transmission.

Saskia asked, ‘Ideas?’

‘The door,’ said Jago. ‘Why did he open it twice?’

‘Yes. He is the only person in the car. What model of car is that? Does it have an advanced computer?’

Besson shook his head. ‘That’s a Merc with a hands-off driving module. The computer is thick.’

Saskia approached the projection. ‘McWhirter said that Proctor used an industrial prototype to detonate the bomb. Perhaps his computer handled the communication too. Picture it: Proctor arrives, he opens the door, then the computer calls him back in. He closes it again and receives the transmission.’

Jago grunted. ‘Maybe the computer announced the caller.’

Saskia clicked her fingers. ‘One day, you will make a fine Kommissar, Deputy.’

‘Gee, thanks.’

‘Paul, can we see a plot of the sound at that point?’

Besson nodded. On the projection, Proctor reversed towards the car and opened the door. Besson wound it back still further. The door closed. He kept cuing. Thirty seconds later—for Proctor, five minutes earlier—the door opened again. ‘Alright,’ Besson said, ‘here’s a visual of the sound.’ The image was replaced by two graphs, each with a tiny peak halfway along. ‘I’ll play it. Quiet.’

As it played, Saskia heard a component deep inside the sound. It might have been a footfall, a snapping branch or a voice.

‘Anyone?’ she asked.

‘Hold on, I can enhance it.’

They waited for Besson to select a smudge in the spectrogram.

‘This is it. Quiet again, please.’

A voice, swept with wind, said, ‘Professor Proctor, it is your daughter.’

Saskia clapped Besson on the back and shared a nod with Garland.

‘N’bad,’ said Jago.

While Jago spoke to his boss about arranging an interview with Jennifer Proctor, Saskia donned her glasses and monitored the virtual workspaces of Besson and Garland, who were engaged in a review of communications between David and Jennifer Proctor. Pictures and text fluttered into the foreground and disintegrated, or joined to represent relationships suggested by Nexus, the semantic parser used by the UK Police Service.

‘Interesting,’ said Garland. ‘David Proctor is flagged for surveillance. Turns out this isn’t the first time he’s blown something up at the West Lothian Centre.’

‘How does that help us?’

‘Here,’ said Besson. In Saskia’s glasses, a data tile rushed towards her. She stopped it with a thought. It was a scan of a paper document, headed ‘GCHQ’. ‘Proctor has been flagged since 2003. Some analysis has already been carried out on his correspondence.’

‘Can we use that to our advantage?’

‘It should speed up the process. Hey, Charlotte, is that video of our man?’

‘Yeah. A robotics conference in Amsterdam in ’21. Looks like Proctor was the keynote. Nothing doing, though.’

Saskia tuned out. Beyond the graphical interface—which she could slide away on command—was a world where she had committed murder. There would be data for that too. Photographs. Video footage. Court documents. Witnesses.

In Cologne.

And yet she could not investigate a datum of it. The previous morning, when she had stood with the revolver in grisly salute, Beckmann had marked her limits. Any attempt to investigate herself would not be tolerated.

Forget it, Brandt.

‘Wow,’ said Garland, ‘look at this.’

It was an email. Garland highlighted some text in the centre and tossed it towards Saskia.

b2kool 2 use an encrypted transmission, dad

‘What did her father say to that?’ asked Saskia.

‘The reply is missing.’

‘Shame.’

‘Kommissarin,’ said Besson. ‘Read these.’

In the latest transmissions, Proctor seldom wrote more than two lines. They were invariably apologetic: ‘Sorry I can’t write any more right now,’ ‘CU Gotta go,’ ‘Write more soon, I prooomise!’, and so on, but the follow-ups were never sent. Jennifer’s e-mails shortened. She made jokes about her father’s tardiness, jokes that became sardonic and accusatory. At the same time, Proctor’s replies became defensive, hurt and confused. The messages described a dying relationship. Saskia could not suppress her sadness.

The e-mails dried up. There was no code.

‘Okay,’ Saskia said. ‘Tune out for a moment.’ She removed her glasses and watched their faces. ‘Charlotte, the e-mail about the cipher. When was that sent?’

‘Back in ’21,’ said Garland.

‘The cipher would have to be complicated,’ Besson said.

Saskia looked at him. ‘You said something earlier about using one-time pads to teach students the basics of cryptanalysis. Maybe she completed it as part of a school project. What was the name of her school? The one in New York?’

‘Wayne’s College,’ said Garland.

‘Find their electronic documents archive. Search for projects by Jennifer Proctor.’

Garland smiled. All three replaced their glasses. Garland tore through the data and Besson and Saskia followed in her slipstream. A list of projects appeared. One was titled: ‘An algorithm for one-time pad encryption using the Homo sapien haploid genome, by Jennifer B. Proctor’.

Quite unexpectedly, Saskia thought of Simon.

‘Bingo,’ she said.

‘Proctor’s DNA was sequenced in 2017,’ said Garland, ‘as part of a research project at the Institute for Stem Cell Research, University of Edinburgh. The sequence was on a thumbdrive in his office when it was raided by MI5. There’s a copy bundled with the GCHQ data. Besson?’

‘Got it. Looks like about 750 megabytes. Not a strong OTP after all, though it might have taken us years to crack using a brute force method. What does Jennifer’s project say about a hash function? I’ll start with no hash and a simple XOR of the data against the DNA sequence.’ Besson smiled. ‘It worked. We have it.’

Detective Superintendent Shand took a box of paperwork from a chair and dropped it into his wastebasket. Saskia settled into the empty seat. Politely, she smiled about the narrow, high-ceilinged office. Jago sat on the windowsill.

‘Always good to meet our continental counterparts,’ said the DSI. He had a grey goatee beard and a lopsided, friendly expression. ‘Treating you well?’

‘Saskia made the breakthrough in the Proctor case,’ Jago said.

‘Team effort,’ she replied. ‘We now have a full transcript of the conversation that took place in the car between Proctor and his daughter.’

Jago gave him a sheaf of loose A4 paper, creased lengthways. The DSI glanced through. ‘Nothing jumps out. You two have had time to think about it. Talk to me.’

‘I have a hunch,’ said Saskia. ‘I think that Proctor has left the country, perhaps via an airport.’

‘Why?’

‘He has received a threat to his life. His daughter says, “Watch your back. Something may happen.” This warning comes true, does it not?’