Brodie shook his head. ‘Something’s not right, Tiny.’
‘How?’
‘Quayle had me on the stand for less than five minutes, and most of that time he spent rerunning the CCTV footage.’
Tiny frowned. ‘What? He voluntarily showed the jury his client kicking shit out of that poor bastard again?’
Brodie nodded. ‘I’m going back in.’
A few heads turned as the door creaked open and Brodie, followed by Tiny, tiptoed into the courtroom to find themselves places in the crowded public gallery. The advocate depute half turned and offered Brodie a quizzical frown. Brodie just shrugged.
Quayle was on his feet again. ‘My Lord, I have only the one witness. I call Mr Raphael Johnson.’
The court officer returned with the witness in short order and beckoned him towards the stand. Raphael Johnson could have been no more than twenty-seven or twenty-eight years old, with a pimply, adolescent complexion and a mane of thick dark hair that tumbled over narrow shoulders. His T-shirt, beneath a hooded leather bomber, was emblazoned with the faded red logo of some unidentifiable creature breathing fire. His jeans were frayed at the knees and concertinaed over the baseball boots that were once again in fashion. Brodie clocked the nicotine-stained fingers and thumb, his bloodshot eyes and reddened nostrils betraying a likely acquaintance with a certain white powdered substance. Though perhaps Brodie was doing him an injustice. Maybe he simply had a cold, or was recovering from the latest mutation of Covid. It was hard to tell the two apart these days.
He affirmed, rather than take the oath. When asked to tell the court who he was, he called himself Raff, and described his occupation as a computer programmer with special working expertise in audiovisual manipulation.
‘Who is your employer?’ Quayle asked him.
‘I’m self-employed, mate.’
‘And your qualifications?’
‘First-class honours degree in computer science from Strathclyde University.’
‘Tell me about the process of video manipulation known as “deepfake”.’
Raff made a snorting sound. ‘No one calls it that any more, mate. Neural masking. That’s what it’s known as these days.’
‘Tell us about it.’
The advocate depute was on his feet. ‘Objection, my Lord. Relevance?’
Quayle raised a finger. ‘Coming to it.’
The judge nodded. ‘Be quick then, Mr Quayle.’
Quayle nodded and returned to the witness. ‘Mr Johnson?’
‘The technology’s about thirty-five years old. Originated somewhere in the early twenty-tens, with the development of software called GAN.’
‘Which is what?’
‘Well, it stands for generative adversarial network, in which two neural networks use AI to out-predict one another.’
It was clear that no one in the courtroom had the least idea what he was talking about. In an attempt to be helpful, the judge leaned forward and said, ‘I take it we’re speaking of artificial intelligence?’
‘Yes, Your Honour. It’s kind of complicated to explain, but we’re talking about video here, and what GANs did was produce fake videos that you really couldn’t tell were fake. The two neural networks do different things. One of them is a generator; the other we call a discriminator.’
‘And in layman’s terms?’ Quayle was hoping for more clarity.
‘Well, in the early days, GAN was used to superimpose celebrity faces on to the participants in porn videos. Give the generator a few videos, or even some still samples of the celebrity face, and it would seamlessly superimpose it on to the target porn actor. You, or I, maybe couldn’t tell that it had been done. But the discriminator would scan the video and find lots of faults with it. The generator would learn from that, redo the original and let the discriminator scan it again. That process would go on many times until, finally, it was virtually impossible to tell that the video wasn’t genuine.’
Quayle said, ‘And is it still used for that purpose?’
‘Nah.’ Raff shook his thick mane. ‘Nobody does that any more. The software has advanced a lot since then. It has much more sophisticated applications now.’
‘Such as?’
‘Well, you’ve probably read they’ve started making movies with actors who’ve been dead for years, even decades. Big stars of the past. They employ unknown actors to make the film, then superimpose the faces of the dead stars on to them. Bingo! You’ve got Cary Grant playing the latest incarnation of Batman. Or Marilyn Monroe playing herself in a brand-new biopic. They can do the same thing with the voices, too. So...’ He shrugged. ‘CGI went out of business.’
Again the judge leaned forward. ‘CGI?’
‘Computer-generated imagery. It’s how they used to turn a dozen people into a thousand in the movies, or make a scene shot in a studio seem like they were in the Bahamas. Pretty crude stuff by today’s standards.’
Quayle cleared his throat and steered Raff gently back to the subject in hand. ‘This neural masking,’ he said. ‘Just how convincing is it?’
An expression of amusement escaped Raff’s lips in a tiny explosion of air. ‘Mate, you can’t tell it’s not genuine. Unless you have the next-generation AI software — which likely won’t even exist yet — there’s no way to tell that it’s not the real McCoy.’
Quayle nodded sagely, as if he understood every nuance of the technology being described. ‘Are you able to show us an example?’
‘Well, as you know, I prepared a short video by way of demonstration.’
The advocate depute was on his feet again. ‘My Lord...’
But the judge was one step ahead of him. ‘Mr Quayle, you are stretching the court’s patience. This had better be good.’ There was, however, no doubt in anyone’s mind that his lordship was as intrigued as everyone else to see Raff’s video.
‘Thank you, my Lord.’ Quayle nodded towards his clerk and the video screens around the courtroom flickered once more, before the video of the assault on the levee began replaying.
The judge frowned. ‘That’s the wrong video, Mr Quayle.’
Quayle’s smile was almost imperceptible. ‘No, my Lord, it’s not.’
Eyes drawn by this exchange returned to the screens as Jack Stalker turned to confront his victim, and his face was caught in full street-light glare for the first time. Except that it wasn’t Stalker. There was an involuntary collective gasp in the courtroom as DI Cameron Brodie’s superimposed face snarled and pushed Archie Lafferty to the ground before kicking him repeatedly about the face and head. So convincing was it, that there was not a single person in the courtroom who would not have sworn that it was Brodie.
Those same eyes tore themselves away now from the video to glance at Brodie himself, sitting in the public gallery, before returning to the screens, anxious not to miss the moment. Brodie’s face burned with shock and embarrassment. And anger.
Chapter Two
The rain was mixed with hail, turning to ice as it hit frozen ground and making conditions treacherous underfoot. Such little light penetrated the thick, sulphurous cloud that smothered the city, it would have been easy to mistake mid-morning for first light.
Overhead electric lights burned all the way along the corridor, making it seem even darker outside, and turning hard, cream-painted surfaces into reflective veneers that almost hurt the eyes. Brodie glanced from the windows as he strode the length of the hall. The river was swollen again and seemed sluggish as the surge from the estuary slowed its seaward passage.