How US Secret Service, Charlotte police used cell phone data to track a murder suspect

The confidential source wasn’t an informant.

It wasn’t even a person.

To catch murder suspect Juan Escalante in May 2019, Charlotte-Mecklenburg Police detectives used technology that imitated a cell tower and connected to a phone through a building’s walls. Going off a general idea of where he was, they found Escalante.

He now faces a murder charge. Jury selection for his trial started Tuesday.

CMPD detectives on Monday testified in Mecklenburg County Superior Court on the hardware that led to his arrest and how it’s used. Prosecutors convinced a judge that the cell-site simulator’s use didn’t amount to a Fourth Amendment violation. With the judge’s decision, prosecutors can use evidence that police found with the technology’s help.

Larger questions about department policy, the technology and its effects on privacy and civil liberties went unanswered.

What happened?

Escalante, 23, allegedly shot and killed Domingo Venancio-Tapia on April 29, 2019. The shooting happened outside a South Boulevard restaurant.

Lead investigator Blair Fitch testified Monday the shooting came after an argument. Escalante fired from the passenger seat of a vehicle, Fitch said, then disappeared.

When Escalante’s mother shared a phone number with detectives that her son used recently, CMPD got the tip it needed, another detective testified.

Police didn’t try to call Escalante and ask him to turn himself in. Instead, they got a court order and asked the Secret Service to track the phone, detective Jessica Zinobile testified.

Cell-site simulators function like “the most attractive cell tower in the area,” according to a 2015 Department of Homeland Security memorandum. Phones and other cellular devices in their proximity transmit signals “that identify the device in the same way that they would with a networked tower.”

The information that police get out of cell-site simulators is limited, though, the memorandum says. They only offer the device’s “general direction,” and they don’t grab any communications, it says.

The technology has been used by a number of federal agencies and police departments across the United States. Last year the ACLU said the FBI was still encouraging police to be secretive about the technology.

CMPD does not own or lease its own cell-site simulator, Zinobile said. Instead, it asks other agencies for help.

The Secret Service confirmed Escalante was at a home near the crime scene in May 2019. When a team of CMPD officers showed up and surrounded the house, he peeked out a window.

After an eight-hour standoff, a search warrant, tear gas and forcing their way in, SWAT finally arrested Escalante, according to court documents.

During Escalante’s police interrogation, he waived his Miranda Rights and confessed to the shooting, Fitch testified.

Escalante’s attorney said in court documents that his client told police before the interrogation that he had taken a Xanax, but they continued the interrogation.

Judge rules on cell-site simulator

In a motion to suppress evidence, Escalante’s defense attorney, Rob Heroy, asked the court to find that CMPD tracked the phone without probable cause, and therefore violated the Fourth Amendment, which protects United States citizens from unreasonable searches and seizures.

CMPD’s request for the cell-site simulator “contained three conclusory sentences that Defendant fired the shots that killed the victim, and no other showing of probable cause,” Heroy wrote in his motion to suppress the evidence.

Because none of the data collected by the simulator was preserved, Escalante lost his legal right to discovery, Heroy argued.

Prosecutors disagreed.

There was already an arrest warrant out for Escalante. Police knew his general location, just not a specific address, before tracking the phone, Assistant District Attorney Austin Butler said. And they were looking for Escalante so they could arrest him, not for evidence. Besides, there was nothing to show that the phone belonged to Escalante; it was just a phone that he used, Butler said.

“They would have found this defendant,” the prosecutor told Judge Justin Davis.

Davis agreed. He declined to suppress the evidence.

Civil liberty concerns

Larger civil liberties questions went unanswered.

The main takeaway during Monday’s evidentiary hearing: CMPD’s officers — or at least the two who testified — don’t know much about the technology or how it’s used. They rely on other agencies for help.

Heroy asked: Did Zinobile, the investigator, check that the Secret Service destroyed records it got through the cell-site simulator, as one document created by her said should be done?

“No,” she replied. “I don’t know what (Secret Service) does.”

Did CMPD have any policy on phone tracking?

“I’m not sure what the policy might be,” she said.

Does the department have criteria for when it can and can’t track a phone?

She wasn’t sure. And federal agencies that handle cell-site simulators like the FBI and the Secret Service had offered no guidance, she said.

What data gets collected? And what data is kept and discarded?

Again, she wasn’t sure.

Concerns go back a decade

Cell-site simulators became a topic of local concern in 2014, when The Charlotte Observer reported on their often secretive use by CMPD.

CMPD used a device called a StingRay to pull serial numbers, location and other information about nearby phones, laptop computers and tablets that connect to cellular networks, the investigation found.

In response to the newspaper’s reporting, then-Senior Resident Superior Court Judge Robert Bell said in 2015 that judges began more closely scrutinizing surveillance requests and asking when officers planned to use a StingRay.

FBI and Department of Justice officials have said they consider the devices “pen registers,” which meet a lower legal standard to obtain than search warrants, the Observer reported.

In Escalante’s case, Zinobile requested and got such legal approval.

Pen registers trace signals from phones but do not capture their contents.

Some wording still hinted at defense attorney Heroy’s concerns about secrecy on Monday.

He asked Zinobile: Why did CMPD say in a report that it got its information on Escalante from something confidential, and not a cell-site simulator?

“In your normal vocabulary, confidential source means cell-site simulator?” he asked her.

It was a code word, Heroy said.

“I wasn’t instructed,” she replied. “That’s how I write my narratives.”

Jury selection was still underway for Escalante’s trial on Wednesday afternoon.