It's still unclear which government agency asked federal agents to circle a Predator surveillance drone 20,000 feet above Minneapolis last week during widespread protests over police brutality and the death of George Floyd.

U.S. Customs & Border Protection, which flew the drone over the Twin Cities in the late morning and early afternoon of May 29, declined to answer questions about the operation, saying in a statement only that the aircraft was sent "at the request of our federal law enforcement partners in Minneapolis."

Exactly who asked for the drone is important because Gov. Tim Walz signed a law in May that prohibits law enforcement agencies from using drones and certain advanced technologies such as facial recognition cameras or other mass data collection tools without a warrant. That state law doesn't apply to federal agencies, said state Rep. John Lesch, DFL-St. Paul, who co-authored the legislation.

One of the loopholes in the law, Lesch said, is that it can be difficult to verify if the request for drone support actually originated with a federal agency or with local law enforcement.

"I really want to know to what extent the feds are cooperating with local agencies," he said. "I want to know who's requesting this surveillance drone, who's getting the benefit of that federal data, who is using that data. I think we're entitled to know that."

FBI spokesman Kevin Smith said the bureau has had no use for a drone during the protests over Floyd's death, and that it is "not the agency in question" that ordered up the drone.

The Minnesota National Guard, which has its own military aircraft, also denies flying drones over the city and did not request any drone support from Customs & Border Protection, a spokesman said.

Walz has said he has been in touch with military authorities in Washington to discuss logistical and intelligence support as authorities worked last weekend to regain control of the streets in Minneapolis and St. Paul. His office didn't return phone calls and e-mails seeking comment.

Knowledge of the drone was only made public after Jason Paladino, an investigative reporter with the Project On Government Oversight, posted images of its flight path online. He and other flight watchers used open-source flight data from ADS-B Exchange to trace the aircraft as it circled in an almost perfect hexagon above the city for more than an hour. The aircraft was identified as CBP104, a Customs & Border Protection Predator B drone based in Grand Forks, N.D.

The drone, an older model that carries no weapons, was originally designed by the military to locate and direct bombs in foreign wars. It is capable of spending up to 20 hours in the air and provides detailed live video on the ground from great distances, according to a Customs & Border Protection fact sheet.

The agency said it bought the drones to help its counterterrorism operations and to spot illegal border crossings, and it has been using Predator drones to help law enforcement agencies since 2005.

Customs "routinely conducts operations with other federal, state and local law enforcement entities to assist law enforcement and humanitarian relief efforts," a spokesman said in a statement.

The drone sent over Minneapolis was "preparing to provide live video" to law enforcement officers on the ground, "giving them situational awareness, maximizing public safety, while minimizing the threat to personnel and assets," the statement read. "After arriving into the Minneapolis airspace, the requesting agency determined that the aircraft was no longer needed for operational awareness and departed back to Grand Forks."

Members of the U.S. House Committee on Oversight Reform announced late Friday that they were starting an investigation into the use of the drone over Minneapolis.

In a letter to the secretary of the Department of Homeland Security, which oversees Customs & Border Protection, representatives demanded a list of all jurisdictions to which the drone was sent, any communication with local or federal agencies about the drone, whether any video was recorded or pictures taken over Minneapolis, and whether any federal or local agents used facial recognition technology, among other demands.

"The deployment of drones and officers to surveil protests is a gross abuse of authority and is particularly chilling when used against Americans who are protesting law enforcement brutality," read the letter, which was signed by five Democratic members of Congress.

Civil liberty advocates have denounced the use of the drone, citing the agency's lack of privacy protections and the potential impact military technology could have in tracking citizens who have broken no laws.

"The fear is that drones are small, quiet and they're uniquely suited for secret surveillance," said Julia Decker, policy director of the ACLU of Minnesota.

There is often very little transparency from the government in how data collected from advanced technologies such as drones are used, said Alan Rozenshtein, a professor at the University of Minnesota Law School and a former federal prosecutor and lawyer in the Department of Justice's National Security Division.

"And when you can attach cameras to drones that can run through sophisticated facial recognition software and that can track people's locations in a large database, that obviously raises concerns," Rozenshtein said.

The common phrase that technology has outpaced legislation can be misleading, he added.

"It's not right to say, 'Oh, technology is ungovernable,' " he said. "It's governable. You just need to have a governing framework and we have failed to impose that."

One school of thought holds that law enforcement or federal agencies should be banned from using drones, Rozenshtein said. Realistically, they may simply be too effective and too cheap to eliminate, he said.

"It raises these hard questions of how effective do we want law enforcement to be and what is the cost of that effectiveness," he said. "Every day we are getting closer and closer to a decision point on that."

Greg Stanley • 612-673-4882