Soon after news broke that Tim Walz would join the Democratic ticket as a prospective vice president, his opponents coalesced on what they see as a major weak spot in the governor's record: his response to the 2020 Minneapolis riots.

His Republican rival, JD Vance, told crowds that Walz "let rioters burn down Minneapolis." The soundbite appeared in a new campaign ad for Donald Trump's ticket, cut over footage of rampant fires and looting, followed by more claims on social media that Walz "was nowhere to be found" during the civil unrest.

Walz was a little more than a year into his first term as governor when Minneapolis police officer Derek Chauvin murdered George Floyd, and video of the fatal encounter ignited five days of protests that evolved into riots. The unrest caused an estimated $500 million in damages to Twin Cities buildings, culminating on May 28 with the torching of the Third Precinct police station. Walz ultimately imposed a citywide curfew and deployed the Minnesota National Guard; the soldiers and other law enforcement snuffed out most of the violence by May 30.

In the four years since, politicians in Minnesota have debated whether the Guard should have been deployed earlier, and have traded blame as to who is at fault for allowing the situation to spiral out of control.

Through videos, interviews, data requests, city and state investigative reports and other public documents, the Star Tribune has pieced together a timeline of Walz's response to the riots. It began with a promise to protect the rights of peaceful protesters, then turned to pleas for them to go home amid destructive demonstrations, and ended with Walz blaming leadership in Minneapolis City Hall for their "abject failure" to suppress heavy looting and arson.

Walz did not respond to requests for comment for this story. Former President Donald Trump mentioned the Minneapolis unrest in an attack on Vice President Kamala Harris during the Sept. 10 presidential debate.

May 27: Outrage prompts unrest

Walz held his first press conference about 48 hours after Floyd's killing, promising that the Bureau of Criminal Apprehension would investigate the fatal encounter and expressing a desire for a federal civil rights probe. Chauvin and the other three officers had already been fired.

The night before, thousands had marched from the location of Floyd's death to the Third Precinct on East Lake Street. The protesters had been mostly peaceful, though some had broken windows at the police station and in squad cars. Minneapolis police responded by shooting rubber-coated bullets and chemical irritants indiscriminately into the crowd without issuing any official dispersal order, and some threw rocks back at them.

Walz said he shared the "urge of just a primal scream" watching the bystander video, and that protesting is "how people express their pain, process tragedy and work to create change."

"I would encourage them to do so with a mask, to socially distance," he said. "We certainly don't want to see things turn violent in any way, but I also think this is a pretty normal response."

Later that evening, looters broke into a Target store across the street from the precinct. Mayor Jacob Frey called Walz around 6:30 p.m. to ask that he send in the National Guard. "We expressed the seriousness of the situation. The urgency was clear," Frey told the Star Tribune in 2020. "He said he would consider it."

At 8:13 p.m., Minneapolis Police Chief Medaria Arradondo forwarded an email to Minnesota Public Safety Commissioner John Harrington asking for the Guard and providing "mission plan" details. "MPD has expended all available resources," the email said, including assistance from surrounding law enforcement agencies.

That night, rioters set ablaze an AutoZone across the street from the precinct and destroyed several other buildings.

Walz tweeted that the area near the precinct had become "extremely dangerous."

"For everyone's safety, please leave the area and allow firefighters and paramedics to get to the scene."

May 28: Assault on Third Precinct

U.S. Gen. Joseph L. Lengyel of the National Guard warned two of the highest-ranking officials at the Pentagon that the situation in Minneapolis was about to get a lot worse.

Lengyel said the Minnesota National Guard was expecting up to 75,000 people to descend on the city that weekend, in emails to Deputy Secretary of Defense David Norquist and Chairman of the Joint Chiefs of Staff Mark Milley. The Guard had 200 military police officers standing by to assist.

"They are prepared to be armed should MPD and the Governor request it," Lengyel wrote, in emails obtained by the Star Tribune through a Freedom of Information Request.

State Adjutant General Jon Jensen followed up an hour later with more details, saying he expected a "late afternoon" deployment.

Walz activated the Guard at 2:30 p.m. and declared a peacetime emergency. The Guard was given missions to support the Minneapolis Fire Department, St. Paul critical infrastructure and the State Capitol complex.

Crowds were far smaller than expected that night, but still overwhelmed the law enforcement response. Police surrendered the Third Precinct around 10 p.m. It was soon breached by a man with a Molotov cocktail and by midnight the south Minneapolis police station was engulfed in an inferno.

May 29: Guard mission expands

Around 12:15 a.m. Friday, Walz authorized a new mission for the Guard at the Third Precinct. By the time the soldiers arrived, around 3:45 a.m., the building had been burning for hours.

Jensen said the delay also came from lack of information, such as details related to equipment for the mission, and he was concerned about soldiers moving into an unfamiliar area in the darkness.

Walz said "there's an argument to be made" that adding soldiers to a protest over police brutality could be a "catalyst" to the situation, and he was trying to strike the right balance.

"You will not see that tonight," he said, vowing to restore order heading into the weekend. "There will be no lack of leadership and there will be no lack of response on the table."

"I will assume responsibility if the issue was the state should have moved faster — that is on me."

Yet, widespread arson, looting and violence continued through parts of the city that night, forcing residents to flee their homes or douse flames with buckets of water and garden hoses.

May 30: Soldiers across the Twin Cities

Shell-shocked residents held meetings Saturday in city parks and at neighborhood intersections, sharing safety tips and organizing patrols with makeshift weapons to protect their own homes.

A somber Walz struck a new tone at his press conference: "The situation in Minneapolis is no longer in any way about George Floyd."

That night, several thousand National Guard soldiers dispersed across the Twin Cities in an attempt to restore order. MPD and state patrol clamped down on anyone out past curfew, firing rubber-coated bullets and tear gas to clear crowds and making mass arrests. The use of force targeting journalists led to several major lawsuits and expensive settlements.

Walz hailed a night of fragile peace in Minneapolis, following what he called "the most complex public safety operation in our state's history."

The aftermath

On June 1, Trump privately praised Walz's response to the riots, saying on a call to governors that Walz "dominated" the situation and other states should follow his example, according to audio obtained by ABC last week.

"I was very happy with the last couple of days, Tim," Trump said. "You called up big numbers and the big numbers knocked them out so fast it was like bowling pins."

Meanwhile, Minnesota Senate Republicans released a scathing report accusing the governor and other elected officials of being too sympathetic to the plight of the protesters, "causing them to lose sight of their responsibility to protect the public from criminal acts committed during the riots."

The city and state each commissioned independent after-action reports. They identified a breakdown in communication, including Minneapolis failing to enact its emergency planning protocols.

Neither points to Walz — or any other individual — as being solely responsible.

Star Tribune staff writer Abby Simons contributed to this report.