The verdict suggested that the jury agreed with prosecutors’ arguments that Mr. Arbery posed no imminent threat to the men and that the men had no reason to believe he had committed a crime, giving them no legal right to chase him through their suburban neighborhood. “You can’t start it and claim self-defense,” the lead prosecutor argued in her closing statements. “And they started this.”

Though the killing of Mr. Arbery in February 2020 did not reach the same level of notoriety as the case of Mr. Floyd, the Black man murdered by a white Minneapolis police officer three months later, Mr. Arbery’s death helped fuel widespread demonstrations and unrest that unfolded in cities across the country in the spring and summer of 2020.

The case touched on some of the most combustible themes in American criminal justice, including vigilantism, self-defense laws, the effects of widespread gun ownership and the role of race in jury selection.

Like many other recent episodes involving the killing of Black people, the confrontation was captured on video that was eventually made public. Unlike many of the others, the video was made not by a bystander but by one of the defendants, Mr. Bryan.

From the beginning, Mr. Arbery’s family and friends raised questions about local officials’ handling of the case. The three men who were later charged walked free for several weeks after the shooting, and were arrested only after the video was released, a national outcry swelled and the case was taken over by the Georgia Bureau of Investigation.

Jackie Johnson, the local prosecutor who initially handled the case, lost her bid for re-election in 2020 and was indicted this year by a Georgia grand jury, accused of “showing favor and affection” to Gregory McMichael, a former investigator in her office, and for directing police officers not to arrest Travis McMichael. The case was ultimately tried by the district attorney’s office in Cobb County, which is roughly 300 miles away from Brunswick in metropolitan Atlanta.

The case brought political and legal upheaval. Gov. Brian Kemp, a Republican, signed a hate-crimes statute into law, and sided with state lawmakers when they voted to repeal significant portions of the state’s citizen’s arrest statute.

During the trial, defense lawyers relied on that citizen’s arrest law, which was enacted in the 19th century. They argued that their clients had acted legally when, on a sunny Sunday afternoon in February 2020, they set out in two pickup trucks in an effort to detain Mr. Arbery, an avid jogger and former high school football player who spent nearly five minutes trying to run away from them.

Eventually trapped between the two pickup trucks, Mr. Arbery ended up in a confrontation with Travis McMichael, who was armed with a shotgun and fired at Mr. Arbery three times at close range. Mr. McMichael testified that he feared that Mr. Arbery, who had no weapon, would get control of the shotgun from him and threaten his life.

Over the 10 days of testimony in the trial, prosecutors challenged the idea that an unarmed man who never spoke to his pursuers could be considered much of a threat at all.

“What’s Mr. Arbery doing?” Linda Dunikoski, the lead prosecutor said in her closing statement. “He runs away from them. And runs away from them. And runs away from them.”

The verdict, read aloud in a packed, windowless courtroom in the Glynn County Courthouse, came at a time when Americans were already divided over the acquittal, a few days earlier, of Kyle Rittenhouse. Mr. Rittenhouse, who asserted that he was acting in self-defense, fatally shot two men and wounded another during protests and violence that broke out after a white police officer shot a Black man in Kenosha, Wis.

Before the verdict in the Georgia case, some observers worried that the racial makeup of the jury — which included 11 white people and one Black person — would skew justice in the defendants’ favor.

Superior Court Judge Timothy R. Walmsley oversaw the proceedings. When he approved the selection of the nearly all-white jury, he noted that there was an appearance of “intentional discrimination” at play, but he said that defense lawyers had given legitimate reasons unrelated to race when they moved to exclude eight Black potential jurors in the final stages of the selection process.

Before the verdict, Wanda Cooper-Jones, Mr. Arbery’s mother, said she had faith in the power of the facts that the jurors were shown. “I’m very confident that they’ll make the right decision once they see all of the evidence,” she said.

Mr. Arbery’s family said he was out jogging on the day of his death, but defense lawyers said no evidence had emerged to show that Mr. Arbery jogged that day into the defendants’ neighborhood of Satilla Shores, just outside of Brunswick, a small coastal city.

Video footage showed Mr. Arbery, dressed in shorts and a T-shirt, walking into a partially built house in the neighborhood shortly before he was killed. It was a house he had walked into numerous times before. Each time, surveillance video showed him wandering around the property, but not taking or damaging anything. The owner of the house told police that items had been stolen from a boat that was sometimes stored on the property, though he was not sure the boat was there when the thefts occurred.

General concerns about property crime in Satilla Shores were widespread in early 2020, residents testified at the trial.

Travis McMichael told the police that he had seen Mr. Arbery outside the partially built house one evening 12 days before the shooting. During that encounter, Mr. McMichael said, Mr. Arbery put his hands in his waistband, as if reaching for a gun. Mr. McMichael called 911 that evening. Mr. Arbery ran away.

On the day of the shooting, a neighbor across the street saw Mr. Arbery in the house and called the police. Mr. Arbery left the house soon after, and ran down the street. Gregory McMichael spotted him and, along with his son, jumped into a truck and gave chase. Moments later, the third defendant, Mr. Bryan, began chasing Mr. Arbery as well.

At the trial, defense lawyers sought to show that the men were acting that day out of a “duty and responsibility” to detain a man whom they felt they had reasonable grounds to believe was a burglar, as Robert Rubin, a lawyer for Travis McMichael, put it. In her closing argument, Laura D. Hogue, a lawyer for Gregory McMichael, noted that Mr. Arbery had been on the property before and said he had become “a recurring nighttime intruder — and that is frightening, and unsettling.”

Travis McMichael was the only defendant to take the stand. He told the court he took his shotgun out during the pursuit because his U.S. Coast Guard training had taught him that showing a weapon could de-escalate a potentially violent situation.

He testified that he believed he had little choice but to shoot Mr. Arbery once they clashed. “It was obvious that he was attacking me, that if he would have gotten the shotgun from me, then this was a life or death situation,” he said. “So I shot.”

In her final arguments, the lead prosecutor, Linda Dunikoski, pushed back against the idea that an unarmed man running down the street would constitute a threat to three men, two of whom were armed, in a pair of pickup trucks.

The men launched their attack on Mr. Arbery, she said, “because he was a Black man running down the street.”

During the trial, influential civil rights leaders including the Rev. Al Sharpton and the Rev. Jesse Jackson appeared in the public gallery of the courtroom with members of Mr. Arbery’s family. Kevin Gough, a lawyer for Mr. Bryan, tried repeatedly to persuade Superior Court Judge Timothy R. Walmsley to bar “Black pastors” from attending the trial, arguing that their presence was unduly influencing the jury.

The comments sparked widespread outrage, culminating with a large demonstration outside the courthouse by activists including Martin Luther King III, son and namesake of the nation’s most revered civil rights leader.