Jurors in northern Michigan acquitted three men on Friday who were accused of providing support to a plot to kidnap the state’s Democratic governor, Gretchen Whitmer.
The verdict was likely to be the final chapter in a sprawling and closely watched domestic terrorism case, and it was a significant defeat for prosecutors, who have gotten mixed results in courtrooms across the state since they filed charges in the case nearly three years ago.
Three previous trials related to the plot yielded five convictions and two acquittals. Four other defendants pleaded guilty.
The trial of the three men in northern Michigan — Michael Null and William Null, who are twin brothers, and Eric Molitor — focused on the volatile months before the 2020 presidential election, when the Covid-19 pandemic led to lockdowns and Michigan was a fiercely contested swing state.
Against that backdrop, state prosecutors said, a group of men with antigovernment beliefs, militia ties and anger over pandemic lockdowns came together and began concocting a plan to abduct and possibly kill Ms. Whitmer at her rural vacation home, and perhaps incite a civil war in the process. Some of the men discussed attacking the governor’s security detail and blowing up a bridge to hinder the police response to the kidnapping. The men were arrested in October 2020, before any attack took place.
Prosecutors said the Null brothers and Mr. Molitor each went on a scouting mission to the vacation home and helped advance the plot. They were charged with providing material support for a terrorist act, which carries a penalty of up to 20 years in prison.
Unlike some of the men who have been convicted in federal court, they were not accused of orchestrating the kidnapping plot. Still, prosecutors told the jury, the men were dangerous and wanted public officials to face harm.
“All the defendants here hated our government,” William Rollstin, a prosecutor, told jurors in his closing statement on Wednesday. “All the defendants here hated police officers. They thought police officers were the enemy and they were willing to go to war with them.”
But defense lawyers tried to downplay their clients’ actions. They suggested that the men were minor players who did not know much about the plans to harm Ms. Whitmer, were egged on by F.B.I. informants and were caught up in the overheated politics of 2020.
During the trial, William Barnett, a lawyer for Mr. Molitor, noted for the jury that Ms. Whitmer had blamed Mr. Trump’s rhetoric for the plot.
“It’s all politics, folks,” Mr. Barnett said in his opening statement. “There’s something going on here. I don’t know what’s going on. But it looks like weaponization of the government.”
The latest trial, held in state court in Antrim County, echoed many of the themes aired in the earlier trials.
Prosecutors said the Antrim County defendants were aiding the leaders of the plot, Barry Croft and Adam Fox. Federal jurors found that Mr. Croft and Mr. Fox had planned to kidnap Ms. Whitmer and destroy a bridge leading to her home. Mr. Croft is serving a nearly 20-year prison sentence, and Mr. Fox is serving a 16-year sentence.
Antrim County is politically conservative, and Donald J. Trump received more than 60 percent of the vote there in 2020, even as Joseph R. Biden Jr. won the race statewide. When Ms. Whitmer won re-election in convincing fashion last year, her opponent carried the county by a 14-point margin.
As the acquittals were read on Friday, all three defendants became visibly emotional. “You gentlemen are free to leave,” the judge said.