Chapter 24

CHAPTER 24

P ARIS

"This is the last meal I'm buying until you crack the encryption on that flash drive," Brunelle said as she set down two Styrofoam containers on MoMo's desk, loaded with halal food.

"I'm working as hard as I can," the young man replied.

"La Crim cracked the same guy's iPhone yesterday."

MoMo wasn't impressed. "It's a six-digit password. Everybody thinks iPhones are impossible to crack. They're not. Obviously. "

Brunelle was in a disagreeable mood. Shortly after she returned home from Powell's apartment last night, heavy thunderstorms had moved in, keeping her awake. To top it off, in the elevator on the way down, Gibert had suggested they go for a drink before calling it a night.

He was concerned about the "tension between them" and wanted to "clear the air." She said no to the drinks and told him to get over it, as she had done awhile ago. Either that, or he should see a therapist. His guilt wasn't her problem.

When the storms finally abated, it was nearing 5 a.m. She fired off an email to her superior saying that she would be following a lead this morning and wouldn't be in until later. Then she rolled over and, after more tossing and turning, was able to grab a few hours of sleep.

Rolling into the office, having consumed two coffees at her apartment, one at the Métro station and another just outside DGSI headquarters, she stopped by MoMo's desk and tried her best to be nice. She knew what she could be like when she hadn't slept well. Sometimes all the coffee in the world was incapable of improving her attitude.

Without looking up, MoMo offered to work through lunch, but only if she agreed to go get it for him. The urge to choke him, right there at his workstation, was strong, yet she maintained her professionalism, took a breath, and waited for it to pass.

On the way back with the food, she made a decision. DGSI often hired outside hackers. If MoMo couldn't get the job done by the end of the day, that was going to be her next move.

Normally, she would have to get approval, as well as funds, from higher up, but since she'd removed the flash drive from the crime scene, that could pose multiple problems for her. Better to keep it under the radar. Heading back to her office, she reread a text Gibert had sent on her way to work.

His officers had canvassed residents of the rooftop apartments adjacent to Jadot's and, as Brunelle had suspected, at least one of them had heard something the night of his murder.

It was described as a thud of some sort. Too heavy to have been a pigeon, but the resident wasn't sure if it had been a person. It was raining pretty hard, she only heard it once, and she had been listening to an audiobook with AirPods in her ears at the time.

Officers had done a full search of her roof, as well as the others nearby, but hadn't found anything. The same, unfortunately, was true for the new dump of CCTV footage they'd received. In the race to solve Jadot's murder, Gibert and his vaunted la Crim were starting to fall out of medal contention.

She was halfway back to her desk when something clicked in her brain. That was it! Turning around, she trotted back to MoMo.

"Still nothing," he replied. The irritation was evident in his voice as he ate his lunch and continued to work on the flash drive.

Brunelle let his attitude slide. "Do you remember the Depeche Mode concert a couple of months ago? It was at the Accor Arena."

"I don't like old-people music."

"A, it's not old-people music," she responded, "and B, would you stop what you're doing and look at me, please?"

MoMo did as she asked, leaning back in his chair and gnawing on a skewer of kofte.

"That was the concert where they first introduced AVS."

"Algorithmic video surveillance?" he asked.

Brunelle nodded.

In the run-up to the Olympics, France had introduced a ton of new, high-tech security measures. The idea behind AVS was to use artificial intelligence to help thwart terror attacks such as the 1996 Olympics bombing in Atlanta and the 2016 truck attack in Nice. France was the first country in the European Union to employ AI-assisted surveillance and it was only accessible to a handful of law enforcement and intelligence agencies.

"I forgot they tested it at that concert," MoMo stated. "What about it?"

"We're one of the agencies that has access to it, right?"

"Correct."

"And everyone in your division has been trained on it."

It was now MoMo's turn to nod. "Where are you going with this?"

"From what I've read, the AI is capable not only of facial recognition, but also of gait recognition. So even if we can't see someone's face on a CCTV camera, we can recognize and track them by their walk."

"Technically speaking, yes. That's true. Legally speaking, no. We're not allowed to do that."

Brunelle looked at him. "What are you talking about?"

"The National Assembly crafted very specific parameters as to how and where the software can be used. Only at sports, recreational, and cultural venues to help prevent public order offenses."

"That's all I'm asking for."

"I'm not following you," said MoMo.

"Jean-Jacques Jadot's killer hasn't been spotted entering or leaving the murder scene. There's evidence that the killer came and went via a window at the rear of the apartment. We now know that a neighbor in a close-by building heard a noise on the roof shortly after the time we believe Jadot was murdered."

"And?"

"And my hypothesis is that the killer used the rooftops for ingress and egress. Specifically, I believe the killer did this to avoid being seen by other people and by CCTV cameras."

MoMo took another bite of his kofte and, despite having his mouth full of food, asked, "What's this got to do with the AI software?"

"The fact that we haven't found the killer yet in any CCTV footage doesn't mean he's not there, it just means we're not looking in the right place."

"Still not following you."

Brunelle broke it down for him. "Jadot's apartment is on the Rue Vieille-du-Temple. Do you know what else is on that street?"

"It's a long street."

"The National Archives of France.

"Suppose, just for a moment, that we're dealing with a very sophisticated criminal, possibly even an intelligence operative for a hostile foreign country. Paris isn't London or New York, but we've got a lot of CCTV cameras. This operative knows we're going to be going backward and forward in the footage, trying to find them and identify them. So how would they prevent that?"

"A disguise of some sort?"

"Exactly," Brunelle agreed. "But I'd take it one step further. Jadot was killed shortly before eleven p.m. on a rainy Sunday evening. Not many people are out at that time and in that kind of weather. If I was the killer, I'd wait to make my escape. And if I could, you know where I'd wait?"

"The National Archives?" MoMo asked, midway into another bite.

"Yes," she responded. "The archives are open to the public. I would have come in during the day on Sunday and, having previously surveilled the building, hidden myself shortly before closing. Then, once I was ready, I could climb out onto the roof and cross over to Jadot's building. There I would drop down and enter the window at the rear of his apartment and wait for him to return home. Once he did, I would kill him, retrace my steps, and return to the archives. Then, Monday morning, once it got busy enough, I would walk right out the front door with a group of tourists and disappear."

The forensic digital specialist took his time chewing his kofte. After swallowing what was in his mouth, he replied, "That's a pretty wild hypothesis."

"It also makes sense."

"Maybe, but it doesn't meet the parameters for use of the AI software."

"Of course it does," Brunelle argued. "The National Archives of France is a cultural venue and murder is most definitely a crime against public order."

Raising his left hand, the young man tilted it from side to side as if to say, Maybe yes, maybe no.

"Come on, MoMo. Help me out here," she implored as she pinched her thumb and index finger together. "We could be this close to catching whoever did this. Jadot was a fellow intelligence officer. We owe it to him to do everything we can to solve his murder."

The young man thought about it as he pulled the last piece of kofte off the skewer with his teeth. "There might be one way we can do this," he said. "At least so it's all aboveboard."

"How?"

"We treat it as a practice exercise. We're searching for a fictional bomb suspect who has planted a device at the National Archives. The goal of the exercise is to help DGSI officers better understand how the software can be used. Once we're done, we delete everything. As long as none of the results are used to violate anyone's rights, we haven't run afoul of any of the rules."

"I promise," Brunelle replied, tracing the sign of the cross on her chest. "I will not violate anyone's rights."

MoMo knew her too well. "Just don't get caught. And if you do, don't tell anybody where you got your information."

After accessing the cloud that the National Archives used for its CCTV footage, MoMo entered the time and date range Brunelle had given him, and then set the AI loose.

As the software wasn't perfect, the process had a few hiccups. On multiple occasions it stopped and needed to be redirected. It was young and still learning.

Nevertheless, the amount of faces it could tag, sort, and account for in a matter of minutes was amazing. For each person it identified, the AI cataloged their clothing, any objects they were openly carrying, and their gait.

Brunelle remembered when gait recognition was in its infancy. She had been astonished to learn that each human being's walk was as unique as their fingerprint. Being able to match subjects to their gait was a huge advantage for law enforcement. Bad guys could obscure their faces and change their clothing, but still give themselves away simply by walking past a camera.

The biggest help of all would have been if the French government had erected "readers" across the city to covertly tag and gather cell phone information. It was the logical next step. Once someone had been identified on CCTV, you could then match them to their cell phone and search for their signal. But France wasn't there yet and Brunelle figured she ought to be thankful. If the tech kept going the way it was going, she'd probably be out of a job soon.

Finally, the AI reached the end of its search and MoMo scrutinized his screen. He was toggling between two images.

"What do you have?" Brunelle asked, leaning in closer.

"Studying all entrances and exits at the National Archives, everyone who entered on Sunday, the day of Jadot's murder, is confirmed to have left by the time the archives closed."

"Including security staff?"

"Security staff included," MoMo replied. "The overnight shift can be seen arriving Sunday evening and then departing the next morning."

"So what are the two images you're looking at?"

"According to the AI, these are two different people. The one on the right entered the archives on Sunday, but never exited. And the one on the left exited on Monday, but never entered."

"You can't see the faces very well in either shot."

"Agreed. That's why the AI is defaulting to gait recognition. These two individuals don't have the same walk," said MoMo.

"Play the clips for me."

Brunelle watched as Figure One entered the archives on Sunday, a ball cap pulled low, avoiding the security cameras. Then she watched as Figure Two, wearing a different hat and clothing, while also avoiding the cameras, left the archives on Monday morning. Unlike Figure One, Figure Two was walking with a slight limp.

"He's faking it," she said.

"What?"

"The guy who's leaving the archives. Right there. He's faking that limp."

"How do you know?"

"I just know."

MoMo leaned in and rewatched the footage. "You can't fake your gait. At least not long enough to throw off the AI. Your brain can't keep up the charade. You end up defaulting to your normal stride."

"Unless you put something in your shoe."

"Are you serious?"

Brunelle nodded. "All you have to do is put a rock in there. Guaranteed limp. And your brain won't give you away. It's enough of a change to throw off gait recognition."

"The software guys neglected to mention that in our training."

"Of course they did. They want the French government to think the AI's bulletproof. It's good, but it isn't perfect."

"So whose walk are we looking for?"

"Both," she said. "Have the AI flag each of them. In the meantime, can you use the software to tap into the street cameras and see where the figure with the limp goes after the archives?"

"You mean the would-be bomber in our training scenario?" MoMo clarified, reaching for a fresh skewer. "Sure."

A few moments later, he tapped into a series of neighborhood cameras and was tracking the man with the limp.

The man walked for several blocks before stopping in front of a narrow building with a tiny blue door. Producing a key from his pocket, he unlocked the door, stepped inside, and disappeared from view.

"What address is that?" Brunelle asked.

"One Rue de Chapon."

"Run it for me."

"Already ahead of you," said MoMo. "And you're not going to like it."

She watched as a message popped up on his screen.

Removing her cell phone, Brunelle pulled up Gibert's contact and hit dial. When he answered, she said, "I'm texting you a location. Meet me there. And bring a flashlight."