Tim Walz was just over a year into his first term as Minnesota governor when a Minneapolis police officer murdered George Floyd in May 2020, touching off a generation-defining summer of global protests against police brutality and racial inequality.

Four years later, Walz’s handling of the demonstrations — which included mass unrest in Minnesota’s largest cities — is under new scrutiny after Vice President Kamala Harris tapped the governor to be her running mate on Tuesday.

At least two people died during the violence in Minnesota’s Twin Cities, more than 600 arrests were made in the initial days of unrest, and the whole span of rioting and law enforcement response made it one of the most costly and destructive periods of civil unrest in US history. Minneapolis and Saint Paul sustained hundreds of millions of dollars in damage during those riots, and hundreds of buildings were heavily damaged.

Conservatives have charged Walz with essentially allowing rioters to “burn Minneapolis to the ground” and waffling on the deployment of National Guard troops to quell the violence.

Walz wasn’t the main authority in charge of responding to the unrest — that was the task of local officials, including Minneapolis Mayor Jacob Frey. But the task eventually passed to him once it was too much for local officials to handle. Both Walz and Frey’s governments have traded blame and presented their own versions of the events of those days of rage, but the full story of what happened is still not completely known.

The main line of criticism of Walz’s response to the late-spring riots hinges on the time it took for him to deploy the Minnesota National Guard and coordinate with other state and local officials in restoring order.

Floyd was killed on May 25, and large protests, with some vandalism and police violence, began the next day. By the evening of May 27, largely peaceful protests grew more violent, with looting and arson around the city. Frey, the mayor, reportedly contacted Walz that evening and asked for help from the Minnesota National Guard. The city’s police chief then sent Walz’s office a written request for 600 troops, in addition to some other logistical notes.

Walz and his office did not sign an executive order authorizing National Guard deployments until the following afternoon, May 28, at which point much of the city had shut down, businesses were closed and boarded up to prevent looting, and buildings were smoldering after overnight arsons. That night saw some of the worst rioting, violence, and arson, as well as one of the indelible scenes of the protests: the breach and burning of the Minneapolis police’s Third Precinct police station. A few hundred National Guard and Minnesota State Patrol officers had been deployed to Minneapolis by then, but were charged with protecting federal buildings and downtown areas of the city, as well as escorting first responders, instead of immediately going to hot spots.

Walz would later say that the city had not specified where the troops should go — and state and local officials later reflected that there was a breakdown in communication, coordination, and understanding of just how long it would take to get National Guard troops prepped.

The next morning, once National Guard troops and the state patrol had taken control of the area around the station, another lasting moment occurred: the arrest of CNN correspondent Omar Jimenez and his crew while reporting live near the police station.

At a press conference on May 29, Walz would take responsibility for the state patrol’s mishandling of the news crew, saying, “There is absolutely no reason something like this should happen. Calls were made immediately … I failed you last night in that.”

That press conference was also the first time Walz acknowledged that local officials’ response had been an “abject failure” and that he would now be leading the response. He said he had spoken with President Donald Trump and said that his tweets about “shooting” starting after looting were “unhelpful.” He deployed more National Guard troops and instituted a curfew. Still, more violence and vandalism occurred.

The following day, Saturday, May 30, Walz would fully mobilize the National Guard, speak with Secretary of Defense Mark Esper and Chair of the Joint Chiefs of Staff Mark Milley, and acknowledge that the situation had gotten worse because “outside agitators” had entered the region. The protests and riots wouldn’t be fully tamped down in the Twin Cities until June 7.

Throughout the protests, local and state officials sparred with each other over a lack of communication and a misunderstanding of the gravity of the situation. Frey, the mayor, would go on to say Walz had hesitated to step in and take leadership after Frey asked for help.

“Through an extremely difficult situation, I told the truth,” Frey told the Star Tribune a few months later. “I relayed information as best I could to state partners. And we did what was demanded for the sake of our city.”

A Star Tribune investigation found that Frey and his city government had been trying to give Walz and the state Department of Public Safety “what they said they needed to move forward” with deploying the National Guard to Minneapolis’s Third Precinct, where the unrest was concentrated.

The Star Tribune examined timestamped email and text logs and found plenty of correspondence that backed up the city officials’ sequence of events: that they asked for help from the state government repeatedly, provided specifics, and did not get a prompt response. “He did not say yes,” Frey said of Walz. “He said he would consider it.”

The governor’s office, meanwhile, contested many of the mayor’s assertions. Contrary to the documents reviewed by the Star Tribune, Walz’s team argued Frey did not immediately provide an official request and had not specified where the focus of the National Guard should be. The governor’s office also contended Walz acted quickly once the request was received.

“As a 24-year veteran of the Minnesota National Guard, Governor Walz knows how much planning goes into a successful mission,” a Walz spokesperson told the Star Tribune in 2020. “That’s why he pushed the City of Minneapolis for details and a strategy. He ordered the Minnesota National Guard to start preparing Thursday morning which allowed them to deploy to both St. Paul and Minneapolis that evening, per the Mayors’ requests.”

By that point in the riots, state Republicans like then-state Senate Majority Leader Paul Gazelka had also criticized Walz’s response, saying it was “a failure of leadership” because “the governor didn’t take the right action.”

Since the Walz announcement, Republicans have assailed him as “weak, failed, and dangerously liberal,” and zeroed in specifically on his response to the Floyd protests and their aftermath.

Given that the racial reckoning that the Floyd murder kicked off included the rise to prominence of the “Defund the Police” slogan and movement, some conservatives have also claimed that Walz was being “soft on crime” for supporting police reforms in the state that banned chokeholds, created new mental health resources for police and first responders, and required excessive-force trainings. And others in right-wing media have conflated his response to the Floyd murder specifically, which he connected to “systemic issues” with policing and “institutional racism,” with Walz offering excuses for the violence.

In the run-up to his selection as Harris’s potential VP, Walz hasn’t faced too many questions about his response to the 2020 unrest. But he may now face more scrutiny for that time. In response to questions from the New York Times on Tuesday, a Walz spokesperson acknowledged that the riots were “a tragic time” but said that Walz “took action” to keep the city safe.

“Decisions were made in a situation that is what it is,” Walz said of the riots at a press conference earlier this month. “And I simply believe that we tried to do the best we can in each of those.”