In the months before former Minneapolis police officer Derek Chauvin's murder trial for the killing of George Floyd, federal authorities warned local officials to beware of potential cyberattacks on government and court computer systems, and the possibility of white supremacist groups traveling to the Twin Cities area to incite racial violence,

The warnings, which were laid out in a series of internal intelligence briefings, also cautioned about potential threats during other high-profile court cases, including the state and federal trials in early 2022 for the other three officers charged with aiding and abetting Floyd's murder.

"White Supremacist Extremists (WSEs) could emerge and exploit otherwise peaceful protests to engage in violence against law enforcement and others involved in First Amendment-protected activity," said one briefing, which like others reviewed by the Star Tribune was labeled secret, but declassified.

A separate assessment concluded that "it is very likely Minnesota law enforcement and government agencies will face an increased threat of being targeted by cyber actors during the trial period."

The declassified briefings were produced using intelligence from the local FBI office, Hennepin County Sheriff's Office and the Minnesota Fusion Center, part of the state's Public Safety Department. They offer the first inside look into how state and federal law enforcement fielded potential threats for the historic trial less than a year after riots engulfed the city.

Through Chauvin's six-week trial, Minneapolis saw an unprecedented level of security. Hundreds of law enforcement officers were deployed, along with National Guard troops, and the downtown courthouse was turned into a fortress of razor wire fencing and concrete barriers. State lawmakers passed an emergency $7.8 million funding package before the trial to help cover the extra security costs. In all, Hennepin County spent $3.7 million on courthouse security, worker salaries and other trial-related expenses.

But the trial didn't bring the kind of unrest that followed Floyd's death, and it is unclear whether any of potential threats mentioned in the briefings materialized. Still, authorities cautioned that the "diverse threat of domestic terrorism could persist through upcoming trials," according to one briefing.

Another briefing cautioned against additional threats that could include "malicious cyber actors targeting Minnesota state and local networks, or Foreign Intelligence Entities (FIE) conducting targeted collection and surveillance operations."

The city experienced a surge of cyberattacks in the wake of Floyd's murder "led by hacktivist groups, but not during the trial in the spring of 2021," city officials said in a statement.

"The threat landscape is evolving locally in the United States and globally around the world. We have seen an increase in ransomware, crypto-mining, denial-of-service attacks and malware infections over the last few years. The City of Minneapolis is constantly evolving its use of cybersecurity technology and practices to deal with cyber-attacks," the statement read.

In an internal report, federal authorities said they anticipated the potential for "malicious cyber activities" in the form of denial-of-service attacks against government networks, website "defacements" and "doxxing," which involves publishing a person's personal information online.

One state official told federal authorities that in the days after Floyd's death "unidentified malicious actors" caused outages statewide of emergency communication systems by employing directed denial of service attacks. In these so-called DDoS attacks, hackers funnel traffic toward a website until it becomes overwhelmed, according to an internal document.

A Department of Homeland Security report in December 2020 concluded that while there was no "specific, credible reporting indicating domestic terrorists" were planning attacks against critical infrastructure or law enforcement, authorities remained "concerned about the potential for (domestic terrorists) to incite or commit violence with little to no warning" in the buildup to and during the Chauvin trial.

In particular, the report said, the Boogaloo movement — a loose network of anti-government radicals who advocate a second Civil War — was "very likely to take advantage of any regional or national situation involving heightened fear and tensions to promote their violent extremist ideology and call supporters to action."

The local FBI field office declined to comment, and a spokeswoman for the U.S. Attorney's office would not comment on specific threats but noted it had prosecuted several members of the Boogaloo Bois.

Paul Becker, a University of Dayton professor of sociology who has studied white supremacist groups and protest movements, said that last year saw "accelerationism" by certain white nationalist groups. Some violent actors from these groups used the protests of 2020 as an opportunity to sow fear and discord and "try to speed up the downfall" of what they consider a corrupt government, he said.

"They believe eventually everything's going to collapse anyway, and so they believe they can speed it up by creating chaos," Becker said.

During and immediately after the Floyd riots, Democratic and Republican officials said organized groups, ranging from antifascists to white supremacists and drug cartels, incited the violence by launching concerted attacks.

Several Boogaloo Bois members have been convicted of crimes committed during or after the riots. But dozens of charges in state and federal court present a much less sophisticated narrative of disconnected individuals who sought to take advantage of — or were caught up in — the lawlessness.

In the months after the riots, Michael Paul, special agent in charge of the FBI's Minneapolis field office, said a "smattering" of opportunistic crowds amassed spontaneously after news of Floyd's death. But he said he saw no evidence of organized antifa groups fueling the riots, contradicting claims by then-U.S. Attorney General William Barr and President Donald Trump.

Even though the marches and rallies that occurred during the trial were peaceful, the intelligence documents show that authorities continued to monitor possible threats.

Authorities highlighted suspicious activity, including individuals sharing law enforcement movements on encrypted messaging apps and posting instructions on making Molotov cocktails and plans for disrupting "firefighting water supply" by opening fire hydrants near the federal courthouse downtown.

In another instance, internal documents show that authorities detained a man at a downtown hotel, where staff said he could be planning a shooting after he asked for the highest room available. The man, who wasn't identified, had a felony warrant for his arrest, and police found drugs and guns in his hotel room.

Authorities also worried about threats from opportunistic "foreign influence actors" with connections to governments in Russia, China and Iran, who they suggested were "likely to use state media, proxy websites, and social media accounts to amplify criticism of the United States," an internal report said.

The same briefing warned about the potential for foreign intelligence services to use the trial as cover for covert "surveillance and intelligence collection" against law enforcement and government officials. The report singled out China, which authorities wrote had been known to recruit "corporate insiders, students and Chinese citizens and companies" for its "illicit intelligence collection efforts."

The report cites the case of a Chinese national who in June 2020 was enrolled at a local university and was seen photographing license plates of law enforcement and government vehicles parked at a command post in Minneapolis where authorities oversaw their response to the post-Floyd unrest. The student's behavior was flagged as suspicious by a state government official; a check of U.S. Border Patrol records shows that the student left the country and returned to China in August 2020.

As such, authorities said they stepped up their surveillance efforts, even while acknowledging that most protesters were engaging in First Amendment-protected activities.

By all appearances, the potential violence never arrived. But, on the day of the Chauvin verdict as hundreds of demonstrators gathered outside the courthouse to await the jury's decision, National Guard troops stood by, looking for any signs of trouble. There was none. As the verdicts convicting Chauvin of murder were read, the crowd erupted in cheers.