Court overturns murder conviction after finding 'geofence' warrant too broad

The Minnesota Supreme Court in a split decision published Wednesday overturned the murder conviction of a Minneapolis man after finding that a police search for Google location data was too broad. But the justices did not ban law enforcement outright from using so-called geofence warrants.

In April 2021, family members of Manuel Mandujano went to the Fifth Precinct police station in south Minneapolis and reported him missing. After visiting a nearby homeless encampment, they’d learned that Mandujano, 39, had gotten into a fight and was beaten to death with a shovel.

Weeks later, police found Mandujano’s remains in a drainage culvert along a sparsely populated rural road in Castle Rock Township south of Farmington. To track down a suspect, investigators got what’s known as a geofence warrant.

With a judge’s approval, police asked Google for the location history data from every mobile device that appeared in a 65-by-290-foot area around the culvert during the month after Mandujano went missing.

During oral arguments in 2024, Assistant Hennepin County Attorney Adam Petras told the Minnesota Supreme Court that the initial data that Google sent back was anonymous.

“Geofence warrants at their core are like a surveillance camera trained on a specific, fixed, limited area and are actually less intrusive than cell tower dumps, for an example, which involve the gathering of many identifiable phone numbers,” Petras said.

Google’s data showed that a dozen phones had been present along that stretch of rural road in the week after Mandujano was last seen. Eleven belonged to passersby. But one lingered for 10 minutes and registered its location 46 times, including directly over the culvert.

Without seeking an additional warrant, investigators went back to Google for more geographic data about the phone and found that it had pinged its coordinates at a nearby gas station in the 60 minutes prior to appearing at the culvert.

After getting additional approval from a judge, police obtained the personal data associated with the phone and learned it belonged to Ivan Contreras-Sanchez. The 45-year-old admitted in a law enforcement interview that he took part in the killing. A jury convicted Contreras-Sanchez of second-degree intentional murder, and a judge handed him a 40-year sentence.

During the same Supreme Court arguments, defense attorney Jennifer Workman urged the justices to declare geofence warrants unconstitutionally broad.

“We are asking this court to find that geofence warrants are prohibited general warrants because they permit sweeping intrusions into private protected data without a check on law enforcement’s power,” Workman said.

In a 4-2 decision, the court overturned Contreras-Sanchez’s murder conviction. Justice Sarah Hennesy writes that the geofence warrant gave police “unchecked discretion” to determine which of the initial dozen phones that had appeared at the crime scene would be subject to an expanded search.

At the same time the justices upheld the use of geofence warrants, calling them a “useful tool for law enforcement.”

University of St. Thomas law professor Julie Jonas said the court is standing by the Minnesota Constitution’s expectation of privacy for cell phone location data. Jonas said that the decision means that police across Minnesota will need to be more deliberate when they seek geofence warrants.

“I think now a cautious law enforcement agency will also get a warrant at step two, when they want to expand their search beyond that initial step one search area,” Jonas said.

The case now returns to the lower courts, which are expected to determine if Contreras-Sanchez should get a new trial. He remains in custody.

This is the first time that the Minnesota Supreme Court has addressed the constitutionality of geofence warrants.

Chief Justice Natalie Hudson, Justice Paul Thissen, and Justice Karl Procaccini joined Hennesy in the majority. Justice Theodora Gaïtas did not take part in the case.

In dissent, Justice Anne McKeig questioned the wisdom of deciding the matter before the U.S. Supreme Court decides in a similar case. Justice Gordon Moore III joined McKeig in dissent.

Okello Chatrie, who was convicted of robbing a Virginia bank, is challenging the use of geofence warrants on Fourth Amendment grounds. The high court is scheduled to hear oral arguments in the case on April 27.

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