Minnesota prosecutors were so worried a judge would move the murder trial of former Officer Derek Chauvin out of the city where he killed George Floyd that they conducted a mock trial in a deep red rural county to test their strategy, Attorney General Keith Ellison reveals in a new book.

It worked. Ellison was pleasantly surprised that even the mock jurors in Stearns County of central Minnesota would have convicted Chauvin and three co-defendants of manslaughter, and almost all would have convicted them on the top charge of second-degree murder. Two simulated juries in Hennepin County, where the case ultimately stayed, came back guilty on all counts.

"Break the Wheel: Ending the Cycle of Police Violence," will be released Tuesday by Twelve, an imprint of the Hachette Book Group, two days ahead of the third anniversary of Floyd's death on May 25, 2020. Chauvin, who is white, kneeled on the Black man’s neck for 9 1/2 minutes. A bystander video captured Floyd’s fading cries of "I can’t breathe."

"Our themes resonated," Ellison wrote. "Several juries believed that the officers had a duty — moral or legal — to render aid to George Floyd. None were too concerned about the drugs. Even the Stearns County jury thought Floyd’s drug history was irrelevant."

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It is not clear if Chauvin’s defense team also conducted a mock trial. His attorney, Eric Nelson, did not return a call seeking comment.

Ellison said he wrote the memoir because he wanted to provide a guide for other prosecutors and share the lessons his team learned about the difficulty of convicting police officers.

The importance of getting jury selection right was one of the key lessons, Ellison recounts, but so was the value of getting testimony from witnesses who spoke up as Chauvin kept a dying Floyd pinned to the pavement outside a corner store, and, critically, got out their cameras. So was finding medical experts who could make it clear to the jury that Floyd would not have died but for Chauvin's actions.

"Many jurors have often associated Black victims with danger and criminality. Over the expanse of American history, juries have been part of the repeating pattern across the country of acquitting officers who shoot unarmed people, often Black men," Ellison wrote. "The sheer numbers of officers who have been acquitted after killing unarmed citizens is impressive."

Ellison became a national figure in 2006 when he became the first Muslim and the first Black Minnesotan elected to Congress. The Democrat became the state's attorney general in 2019. Criminal prosecutions in Minnesota usually fall to county attorneys. But amid the turmoil and racial tensions that followed Floyd's killing, Democratic Minnesota Gov. Tim Walz asked Ellison to take the lead.

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Ellison recounts in his book how he used his personal connections to assemble a high-powered, diverse team of volunteer and staff attorneys to try the case.

In the end, Hennepin County Judge Peter Cahill, who Ellison praises in the book, kept the trial in Minneapolis, though he tried Chauvin separately from the other three defendants. Ultimately, all four offers were convicted or pleaded guilty to state and federal charges.

Despite extensive pretrial publicity, the court was able to seat a jury for Chauvin, through it took three weeks. Ellison wrote that it was the most diverse jury he had ever impaneled — six Blacks and six whites. He credits Steve Schleicher, a former federal prosecutor in private practice, and jury consultant Christina Marinakis.

"It wasn't just luck," Ellison wrote. "I knew that if we convicted Chauvin, many people would be taking some awesome jury selection work for granted."

For prosecutors, Ellison said in an interview, he hopes their takeaway from the book is that "tough cases like this are winnable" even though roles are reversed. In a normal case, he said, jurors of all colors tend to believe the police, which helps the prosecution. But that makes officers harder to convict, he said. And while jurors typically sympathize with victims, that's not guaranteed in a police case where the defense puts the victim on trial.

For other readers, Ellison said he hopes their takeaway is that ordinary citizens — like the bystanders who took video of the incident and had the courage to testify — can do extraordinary things.

"Those people who were randomly selected by fate on the corner of 38th and Chicago at around 8 p.m. Memorial Day 2020, they didn't know George Floyd, but they saw a suffering human being," Ellison said in the interview. "They stopped and they said something. They couldn't do much more than say something, but they whipped out their cameras and they took pictures of it."