Jeers and violence erupted between Donald Trump supporters and protesters at the Republican frontrunner's rally in Fayetteville, N.C., on March 9. (Jenny Starrs/The Washington Post)

Republican front-runner Donald Trump will not face charges of inciting a riot after a raucous rally in North Carolina last week, the investigating sheriff’s office announced in a news release Monday night.

After reviewing evidence from the rally in Fayetteville, N.C., the Cumberland County Sheriff’s Office concluded that it “does not meet the requisites of the law” to “support a conviction” of inciting a riot following the event, at which an anti-Trump protester was ­sucker-punched as he was led out.

“Accordingly, we will not be seeking a warrant or indictment against Mr. Trump or his campaign for these offenses,” the statement said. “While other aspects of our investigation are continuing, the investigation with regard to Mr. Trump and his campaign has been concluded, and no charges are anticipated.”

Earlier Monday, Ronnie Mitchell, the top attorney for the sheriff’s office, released a statement saying that the office was investigating whether “there was conduct on the part of Mr. Trump or the Trump campaign which rose to the level of inciting a riot.” But by the time the sheriff’s office made its announcement, the charges already seemed unlikely.

“It doesn’t appear that we have sufficient evidence to warrant charging him at this time,” Mitchell had said earlier Monday. Mitchell said he offered legal advice to the sheriff, Earl “Moose” Butler (D), about whether to file charges.

“ ‘Incitement to riot’ requires conduct or words which would cause at least three persons who are assembled to engage in disorderly conduct, as that’s defined under North Carolina law,” Mitchell said. “We have not been able to unearth evidence that [any instances] were incited or motivated by Mr. Trump.”

Trump held a rally in Fayetteville, N.C., on March 9, in which an anti-Trump protester was sucker-punched as the protester was led out of the stands by police. Mitchell said deputies had examined nearly 100 incidents from the rally, including individual protests.

A spokeswoman for Trump’s campaign, Hope Hicks, described Trump’s event in Fayetteville as warm and family-friendly. “There was a great feeling of warmth, well-being and even love in the arena,” she said.

Hicks acknowledged disruptions, but she blamed the protesters and even sympathized with the man who threw the punch.

“In some cases, they used foul language, screamed vulgarities and made obscene gestures, annoying the very well-behaved audience. The people that stood were loud, rude and abrasive,” Hicks said. “On one occasion, while the police were escorting a young man out of the arena, he seemed to lift his hand and make an obscene gesture. We are told a 78-year-old man took great exception to this.”

She said that if anyone had violated the law, “it is the protesters and agitators who are in violation, not Mr. Trump or the campaign.”

Under North Carolina law, a riot is “a public disturbance involving an assemblage of three or more persons which by disorderly and violent conduct, or the imminent threat of disorderly and violent conduct, results in injury or damage to persons or property or creates a clear and present danger of injury or damage to persons or property.”

The charge “inciting a riot” is a misdemeanor, defined as when a person “willfully incites or urges another to engage in a riot, so that as a result of such inciting or urging a riot occurs or a clear and present danger of a riot is created.”

Trump campaigned Monday in North Carolina for the Republican presidential nomination, ahead of that state’s GOP primary Tuesday.

The incident in Fayetteville was captured on videos, which showed an African American protester with long hair and wearing a white T-shirt being led out by sheriff’s deputies as the audience booed. The man extended a middle finger to the audience on his way out.

Then, out of nowhere, the man was punched in the face by a ponytailed man, who appeared to be white, in a cowboy hat, black vest and pink shirt as the crowd began to cheer. The protester stumbled away, and then was detained by a number of the men in uniform.

The protester was later identified as Rakeem Jones.

“Boom, he caught me,” Jones told The Washington Post in a telephone interview. “After I get it, before I could even gain my thoughts, I’m on the ground getting escorted out.”

John Franklin McGraw, 78, was charged with assault and disorderly conduct. On his Facebook page, Butler said he added a charge of “communicating threats” after viewing a video of McGraw, recorded later on the night of the rally, in which McGraw said he enjoyed hitting “that loudmouth . . . who was “not acting like an American,” and threatened next time “to kill him.”

The first outlet to report that Cumberland County investigators were considering the charge was WRAL in Raleigh, N.C.

The incident with McGraw happened in the first few minutes of Trump’s appearance in Fayetteville, and it was the first major disruption of that event. In previous rallies in other states, Trump had suggested that supporters “knock the crap” out of disruptive protesters, and said “I’d like to punch him in the face” as another protester was escorted out. But in this incident, he had not mentioned anything about protesters until around the time McGraw allegedly threw the punch.

“Hello! Uh oh! Ohh! Uh oh! So early. So early. All right, get ’em out! Thank you. We’re gonna have such fun,” Trump said then, as the crowd chanted “Trump!” “We’re gonna have such fun tonight. Get ’em out. Thank you. Do we love our police? Our police are great.”

Later in the rally, in response to another disruption, Trump was more forceful: “Get out of here. Go home to Mom!” he said, as the crowd cheered. “Nasty. Nasty. Why are they allowed to do things that we’re not allowed to do? Can you explain that to me? Really a disgrace.”

Butler, the elected sheriff of Cumberland County, is a Democrat in his sixth term in office.

Trump’s next scheduled event — his campaign called it a “massive rally” — was scheduled to start at 6 p.m. Eastern time at an airfield in Vienna, Ohio, near Youngstown. Attendees were being required to park at a minor league baseball stadium about eight miles away and take buses to the event. At least 26 officers were assigned to provide security at the rally, said Erich Luketich, a supervisor at the Trumbull County 911 dispatch center.

On Monday, a legal expert at the University of North Carolina law school said it can be difficult to prove a charge of “inciting a riot.”

“We do have very strong protections in this country for speech that is unpleasant, that is hateful, that is deeply offensive,” said Mary-Rose Papandrea, a professor at the University of North Carolina School of Law who specializes in constitutional law, civil liberties and national security matters. “But incitement of violence, of damage or harm is not protected. The thing is, meeting the legal standard for incitement isn’t easy. Prosecutors have to meet some very rigorous requirements.”

For decades, prosecutors across the country have interpreted riot statutes to apply only in cases where someone willfully intended to inspire or encourage immediate violence. If Trump were actually charged in this case, Papandrea said, he could argue that he had not meant to encourage physical violence before the punch was thrown.

Janell Ross and Jose A. DelReal contributed to this report.