Ghislaine Maxwell spotted the agents, heard them shout “FBI” and ran to another room inside her secluded New Hampshire compound, slamming the door behind her.
On a desk was a cellphone wrapped in tinfoil, a clue that prosecutors claim shows just how far the accused sex trafficker went to avoid being traced. But the cellphone was her undoing after months in hiding, one she used under the name “G Max” to talk with secret husband Scott Borgerson.
On July 2, two dozen agents stormed the compound and arrested Maxwell for allegedly conspiring with ex-lover and convicted pedophile Jeffrey Epstein to lure and groom teenage girls for him. She has pleaded not guilty to the charges; he killed himself in jail.
The FBI had been tracking the British socialite’s number with cell tower data, but couldn’t come any closer than a square mile of her exact whereabouts. So, the feds turned to cellular intercept, a technology that NYU professor Ted Rappaport helped pioneer.
Every cellphone has two unique numbers — a Mobile Identification Number (MIN) and an International Mobile Subscriber Identity (IMSI) — that make tracking the location possible, Rappaport told The Post.
In the Maxwell case, the FBI obtained a search warrant July 1 that allowed agents to both send and receive signals from the fugitive’s cellphone.
How agents exactly hunted down Maxwell wasn’t laid out in court documents, but law enforcement agencies use two kinds of devices — one that plucks a transmission out of the air, like Rappaport’s Cellscope receiver created in the late 1980s, and one that masquerades as a cell tower.
A receiver, also called an IMSI catcher, “intercepts a transmission over the airwaves, locks on to it and allows a user to follow it with a directional antenna to find out where it’s coming from,” said Rappaport, 60, founding director of NYU Tandon’s Wireless research center.
And, he points out, a transmission doesn’t have to be a call, but simply a registration, or “heartbeat,” that the cellphone gives off every so often to indicate it’s on.
A cell tower imposter, also called a cell-site simulator, broadcasts a signal that’s stronger than a service provider’s tower, tricking a cellphone into connecting with it instead.
Civil liberties advocates fiercely object to all kinds of surveillance technologies, especially cell-site simulators, contending they both violate people’s privacy and the Fourth Amendment, which prohibits unreasonable searches and seizures.
“This tech that mimics a cell tower isn’t just picking up the unique serial number, it’s getting lots of others nearby,” ACLU staff attorney Nathan Freed Wessler told The Post.
The Justice Department does require bystander data to be deleted as soon as a cellphone is located and can be kept no longer than 30 days. Still, “there’s the inherent danger that police suck up information and violate people’s privacy,” Wessler told The Post.
Until a policy change five or six years ago, he said, the FBI “quite frequently” used cell-site simulators without warrants.
Agents had a warrant to go after Maxwell, though Wessler predicted her lawyers would file a motion asserting the FBI violated their client’s Fourth Amendment rights — a standard argument in all kinds of criminal defense cases.
For Wessler, a positive development stemming from the Maxwell case is the unsealing of an affidavit for the search warrant in a matter of months.
“Often, it takes a very long time and is hard for the public to know what kind of invasion technology that the government is using.”