Police split over use of ‘Digital Dragnet’ for tracking your phone


From deadly home invasion robberies to a stolen wallet, law enforcement agencies in the Twin Cities metro area are increasingly using a controversial tool to try to solve cases where physical evidence does not immediately point to a suspect.

Now detectives are counting on Google to lead them to the culprits.

A 5 INVESTIGATES review of court records found several local law enforcement agencies obtained more than 40 search warrants in 2019 — up from less than 20 the year before — ordering Google to reveal the location of every smartphone at or near a crime scene that connected to the company’s services or applications, such as Google Maps, which are often tracking a phone’s precise location.

The warrants, known as “reverse location” or “geofence” searches have raised strong objections from privacy advocates across the country who say the “digital dragnet” sweeps up the personal information of suspects as well as innocent bystanders, and the evidence from one such search warrant is now being challenged in federal court in Virginia.

In Minnesota, police departments appear to be split over how and when to use the new tool, according to the court records analyzed by 5 INVESTIGATES as well as interviews conducted with police brass from several departments.

Digital evidence

When Eden Prairie Police responded to a break-in at Nean Tobacco in November, store owner Sari Flaija provided detectives with surveillance video showing a team of three men getting away with thousands of dollars in cash and merchandise.

“It was really bad,” Flaija said. “I was really angry, upset.” 

Adding to his frustration, the faces of the men in the video were covered by hooded sweatshirts drawn tight. Police reported a single shoe print on the store counter was the only physical evidence the burglars left behind.

About a week after the burglary, court records show a member of the Eden Prairie Police Department obtained a warrant ordering Google to identify every phone that had connected to its services about an hour before and after the crime in an area encompassing the tobacco store, a neighboring shop that was also burglarized and part of a strip mall parking lot.

Eden Prairie police later confirmed they obtained some evidence from Google but recently inactivated the case due to a “lack of suspect information.”


In a recent interview, department and city officials were reluctant to discuss their use of geofence warrants and the privacy concerns surrounding them. Sgt. Bob Davis declined to elaborate much beyond a written statement that had been prepared by the city’s senior communications coordinator.

“Digital evidence is often stored on personal devices or in remote servers owned by thousands of companies,” Davis said. “Digital evidence is also potentially left at every crime scene and this is just one of the ways, one of the methods, that we’re able to obtain that evidence.”

Eden Prairie declined to do a follow-up interview on the subject. 5 INVESTIGATES found that the department is using geofencing more than any other agency in Hennepin County.

It filed for at least ten warrants in 2019—including several for non-violent property crimes such as burglaries or fraud cases—according to 5 INVESTIGATES’ review of court records.

The county’s largest law enforcement agency, the Minneapolis Police Department, filed only two such warrants — both as part of investigations into shootings.

The St. Paul Police Department filed none.

Increase in requests

Yet, Eden Prairie appears to be part of a nationwide trend in law enforcement. In recent court filings, Google revealed it has seen an explosion in the number of “geofence requests” — up at least 1500% since 2017. It received more than 10,000 warrants from U.S. law enforcement agencies in the first half of 2019 alone, according to a company report.

Google did not respond to multiple requests for comment. However, in court filings, the company’s lawyers acknowledged that its location data “provides an intimate window into a person’s life” that allows the government “to travel back in time” to retrace a person’s whereabouts.

“It is not lost on us that there is a privacy concern here,” said Brian Hubbard, the deputy police chief in Crystal. His department has only filed two geofence warrants, including one for a year-old home invasion and homicide case that had gone cold.

“People have to have freedom to move around, and we don’t want to infringe on that. And so we have to weigh that against the public good of we have crimes to solve,” Hubbard said.

Checks and balances

The location data Google collects from users is often far more detailed than what police have gotten from cell phone companies in the past because users’ phones are logging their movements by frequently checking in with Wi-Fi networks and even Bluetooth devices, rather than just cell towers. 

“That’s part of the reason I’m skeptical of this back-and-forth process between the company and police,” said Nate Freed Wessler, a staff attorney with the ACLU Speech Privacy and Technology Project based in New York. “It’s likely that Google’s going to turn it over and that raises really serious questions about overbroad searches.”

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Challenged in court

The central privacy questions about geofence warrants are now being considered by a federal judge in Virginia. Lawyers for a suspected bank robber have filed a first-of-its-kind motion to suppress evidence from Google. They say a geofence warrant that led to charges against Okello Chatrie, 24, is a “modern-day incarnation of a ‘general warrant,'” which is unconstitutional.

Wessler says a general warrant essentially allows police to search every house in a neighborhood and is prohibited by the Fourth Amendment, which protects people from unlawful search and seizure.

“(The geofence warrant) has some disturbing things in common with that kind of a search,” Wessler said. “Should police be able to cast a dragnet, sweeping in information about lots of totally innocent bystanders in an attempt to find one unknown suspect?”

The judge’s decision in Virginia could potentially affect how and when police in Minnesota utilize the new tool.

Currently, none of the 17 agencies surveyed by 5 INVESTIGATES reported having policies that specifically address the use of geofence warrants.

Yet, there is clearly an appetite to expand its use. 

At least six law enforcement agencies have sent investigators for training related to the use of geofence warrants. The Hennepin County Sheriff’s Office is scheduled to host a training session in September.

“I have to acknowledge it would appear this is a fishing expedition for us to look for a suspect and I would acknowledge that’s actually true,” said Deputy Chief Mark Bruley with the Brooklyn Park Police Department. His department sent at least nine geofence requests to Google in 2019—all for burglaries.

Bruley says there are “checks and balances” to ensure police are not treading on people’s rights. 

“We’re not getting people’s identities, we’re not getting people’s bank accounts, we’re not getting people’s names,” he said.

While Google initially only provides police with anonymous ID numbers associated with each phone, investigators in Minnesota can, and have, obtained additional warrants that would reveal more specific information.

Shortly after a shooting in the parking lot of a Holiday Inn Express in Golden Valley last year, investigators with the Hennepin County Sheriff’s Office Violent Offender Task Force were looking for at least four suspects. 

Yet, they eventually obtained a warrant that would require Google to give up “basic subscriber information” of 19 phones in the area. That step in the process could lead to names, e-mail addresses, and other personal information of at least some innocent bystanders.

Google on Friday issued the following statement to KSTP:

“We vigorously protect the privacy of our users while supporting the important work of law enforcement. We have created a process for these specific requests designed to honor our legal obligations while narrowing the scope of data disclosed and only producing information that identifies specific users where legally required.”

Eric Rasmussen can be reached by phone at 651-642-4534 or by email here.