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?’
The DSI arched an eyebrow. ‘I thought that the “something” was a result of Proctor’s own actions.’
Saskia said, ‘I realise, sir, that we are not in a position to verify or falsify Proctor’s charges. But we are also not required to accept them. I mean, we must not accept conclusions unless we make them ourselves from available evidence. Nobody, so far, has been able to produce evidence to show that Proctor is responsible for anything. It is conjecture. A jury might not convict him.’
The DSI was grim. ‘You should attend more trials.’ Seeing Saskia’s expression, he pulled a face, as if to dismiss his own comment.
‘If Proctor is an innocent party, then I believe he will wish to gather more information about his predicament. At the very least, more information would bolster his defence against the charges. Under EU law, it is not illegal for an innocent person to attempt an escape.’
Jago gave her a warning look but the DSI nodded. ‘Well, I can’t argue with your research, Detective.’
‘Kommissarin,’ Saskia said. She felt her voice strengthen. ‘Proctor is a university professor. It is a comfortable existence. We know from his e-mails that his relationship with his daughter is strained. The last few days will have proved to be very difficult, even life-altering. Proctor will undoubtedly feel the need to leave the country. Here he is hunted. In America he is not. His daughter is in America. In addition, she gave him the warning. If he is indeed innocent, then his search for answers must begin with her. Flying out would “kill two birds with one stone”. We must assume it is within his capability.’
The DSI said, ‘I’m with you. Jennifer is his daughter. The person who helped organise his escape is someone who would risk everything for him. Jennifer fits the bill. Was she the woman who broke Proctor out of the Park Hotel? Who knows, maybe her employers—if they are the US government, like you say—helped to falsify her passport and formulate Proctor’s escape plan. If we get her, we get Proctor. But is she still in the country?’
‘I think it is unlikely,’ Saskia replied. ‘If you are correct and she has the backing of the American government, they would advocate a plan with minimum risk. Perhaps she has already risked a great deal by personally overseeing her father’s escape. If they were to attempt an escape together, the probability of their apprehension would increase. In that case, I would suggest that she left immediately via the nearest airport, Edinburgh.’
Jago shook his head. ‘I don’t know. If the Americans really wanted Proctor, why not smuggle him out by military transport?’
‘Secrecy,’ the DSI said. ‘And cost. How much do they want him? What can he be worth?’
Saskia replied, ‘Perhaps everything, perhaps nothing. However, with the correct advice and documentation, there is no reason why Proctor should not be able to leave the country through an airport.’
‘Edinburgh?’ Jago asked. ‘You think he showed up in Northallerton to throw us off the scent?’
‘Why not?’
‘No,’ said the DSI. ‘We had Edinburgh locked down tight. To get lost in the crowd he would need somewhere bigger.’
‘Like where?’ Saskia asked.
‘Heathrow, Gatwick, Luton, Stansted,’ Jago said. ‘Take your pick.’
‘Which is the largest?’
‘Heathrow,’ said the DSI. ‘And its surveillance is poorest due to the volume of traffic. We’ve had a team researching this scenario. If he took a car or a train, he would have left the country by now. If he’s still on the bike, and using minor roads, he could catch a flight at midnight—if he rides hard. Personally, I think he’ll lie low for a week.’
‘Those flights need to be checked, sir,’ said Saskia.
‘I agree with you, Brandt. Check each person who flies to America between midnight and 6:00 am. Check them by hand. If you don’t find Proctor, we can assume he’s already gone or he’s lying low. We have other people working those leads.’
Jago said, ‘There are about thirty-five thousand people who can do that for us, sir. They’re called the Metropolitan Police Service.’
The DSI shook his head. ‘Think. If Proctor takes his holiday tonight, I want us to nab him, not our Cockney friends. No sense having the Met solve our cases.’
‘But Saskia is a neutral party.’
The DSI grinned, revealing a gold canine. ‘It’s that kind of clear thinking that stops you advancing through the ranks, Phil. Saskia is a neutral party accompanied by a Lothian and Borders liaison officer.’
‘Yes, sir,’ Jago said quietly.
‘You two can hitch down to Heathrow with a friend of mine, Sam Langdon. He comes here for the golf. My secretary will give you his number. Have a nice trip.’
He held open the door. Saskia and Jago walked through. In the waiting room, Jago said, ‘I was his mentor when he joined the service.’ He checked the time. ‘Right, we’d better find this Langdon character. Saskia?’
She was watching Besson and Garland at the coffee machine. They looked up and smiled. Even the loneliest person has the memory of company, but she did not even have that.
David glanced at the bike’s dashboard. It was 4:00 p.m. He had been riding for nearly nine hours. It was time to gather the elements of his disguise. He took his lead from Ego, who had downloaded three SAS survival guides and related them to David in a digested, if sensational, form. Ego wanted him to change his vehicle and his clothing. David disagreed. Clothing, yes; vehicle, no. The bike was uncomfortable but it was fast, all-terrain, and easily camouflaged.