Reggie shook his head. “That’s a bit too technical, even for me, which is why we need to get an analyst on board, ASAP.”
“Explain why you can’t do it,” Dillon said.
“Generally speaking, cells are split into three sectors, and each sector has its own antenna. The antennas are erected at 120-degree intervals to ensure the cell gets the best all-round coverage. Each 120-degree arc is called an azimuth. Analysts have access to specialist software that enables them to narrow down a signal to a specific azimuth, whereas I can only tell you which cell the signal went through.”
Dillon’s brow creased into a deep furrow. “So, at best, we can only reduce the search area to a third, not down to a street or a house?”
Reggie nodded. “That’s right.”
“And you can’t work out which azimuth thingy the phone is located within without an analyst?”
“When I make an application for cell site data, I get sent the CELL ID, its location and postcode, which is how I can say which cell covers the area the phone is pinging in and show you the overall radius of its reach. The data also contains the grid reference and the azimuths, but to be able to extract the relevant information and convert it into a chronological report or an evidential package, you need to have analytical training and access to the specialist mapping software. I don’t have either.”
Dillon scratched his head. “I see,” he said, but from the blank look on his face, it was clear that he didn’t.
Jack tried to remember the telephone input he’d received during his SIO course the previous year. As he understood it, at its most basic level a mobile telephone was simply a receiver that worked by using radio waves to communicate with individual masts. The masts then interacted with the host network.
In busy urban areas like Plaistow and Barking, a lone cell might service an area with a one-kilometre radius, and at any given time a mobile phone might be able to detect and measure the signal from as many as six cells.
The instructors had explained that phone analysis, which was still in its infancy in many ways, was a complicated science. Due to their nature, radio signals tend to propagate in an irregular manner, influenced by things like building clusters and topography, which is why the nearest mast isn’t necessarily the one with the strongest signal.
“I’ll speak to Mr Holland first thing in the morning and badger him into providing us with an analyst as a matter of urgency.”
After Reg had departed, Dillon turned to Tyler. “I didn’t understand any of that,” he admitted.
“Don’t worry,” Tyler said, grinning. “You can’t help being thick.”
“I’m not thick,” Dillon replied indignantly, and then his face broke into a wry smile, “just technologically challenged!”
Tyler’s leaned back in his chair, interlocked his fingers and rested his hands against the back of his head. “Dill, first thing in the morning, can you check with Reggie to confirm that the 777 and 321 numbers bedded down together again within coverage of the same cell. If they did, and I’m fairly confident they will have, I’ll need you to get straight onto the TSU to see if we can arrange for them to send out a signal detector van tomorrow night.”
The TSU - Technical Support Unit – were based at Lambeth in South London and, as the name suggested, they handled all the Met’s technical deployments. A signal detector van was basically a vehicle that performed a similar function to a TV licencing van, except that it searched for phone signals and not unlicensed televisions. Of course, it didn’t always work. Sometimes the phone they were hunting was switched off, or it had been left in a room that didn’t receive a signal, but the tactic was definitely worth a try.
“When it’s arranged, can you immediately give George Holland a heads up and then knock out the relevant paperwork.”
“What about if they can’t help?” Dillon asked.
Jack shook his head. “That’s not an option. Tell them this will go all the way up to the Commissioner if they want to argue the toss.”
“Fair enough,” Dillon said, making a note in his daybook. “Leave it to me, oh mighty leader.”
“I have one more request,” Jack said. “I want you to phone the Duty Officer at Plaistow on my behalf and ask the night duty to conduct an early hour’s street search of the area Reggie’s circled on this map.” He held it aloft for Dillon to see. “They’ll be looking for a red four door Rover 216 hatchback.”
Dillon grimaced. “That’s going to make me bloody popular,” he complained.
“Can’t be helped,” Jack said firmly. “Explain that we think it was involved in the murder of a colleague. That should motivate them. As an added incentive, tell them that if any of the cars they put up turns out to be the right one, whoever spotted it gets a crate of beer and a bottle of scotch on me.”
Dillon smiled. “That might soften the blow,” he said. “What’s the index number and are there any distinguishing marks or dents on it?”
“Unfortunately, we don’t have an index, and we’re not aware of anything that makes it stick out.”
Dillon’s raised eyebrow was an inverted tick of incredulity. “Seriously? There could be hundreds of cars that fit the description.”
“I know,” Jack said, “and I want a PNC printout for every car they find, along with details of the exact location where it was parked.”
Dillon sucked in air. “Maybe you should make it two crates of beer,” he suggested.
Leaving Dillon to make the call, Tyler ventured out into the main office to check in with the Intel Cell. As ever, Dean was hunched over his keyboard, tapping away furiously. Wendy was standing by the printer, having just run off some stuff to submit to the MIR. Both looked absolutely shattered.
Thankfully,
