St. Louis ? No criminal charges will be filed against a state lawmaker accused of threatening the campaign manager of a political rival in Missouri, the prosecutor in the case said Friday.

Franklin County prosecutor Bob Parks said in a statement that he found no grounds for charges against Rep. Brian Nieves, R-Washington.

Nieves, 45, has denied that he assaulted and threatened Shawn Bell, who claimed Nieves roughed him up when he visited Nieves’ campaign office the day after the Aug. 3 primary election. Bell, 24, of Jefferson City, was the campaign manager for Dick Stratman, whom Nieves defeated in the Republican primary for a state Senate seat.

Parks was unavailable for comment Friday, a clerk in his office told The Associated Press. The prosecutor told the Washington Missourian that he believed there was an argument between Nieves and Bell but couldn’t prove a criminal act by either person.

Nieves’ attorney said he was pleased with the decision.

“We’ve maintained all along the allegations by Mr. Bell are without any merit,” attorney Michael Payne said.

Bell was disappointed by the decision and will continue to seek a court order requiring Nieves to stay at least 100 feet away from him, said Bell’s attorney, Michael Byrne.

“Mr. Bell is still in shock from what occurred to him,” Byrne said. “Clearly we’d prefer for Mr. Nieves to be charged and prosecuted.”

In a statement filed with police in Washington, about 50 miles west of St. Louis, Bell asserted that Nieves threw him against a wall, head-butted him and slapped him several times, then pulled a black gun out of his pocket, set it on a table and said he was going to kill him.

According to the statement, Nieves later calmed down and said he wouldn’t kill him or put him in the hospital.

Bell also said Nieves told him during the confrontation that people had been following him for three days and that the lawmaker twice told people not to beat up Bell.

The Republican primary for the 26th Senate district was heated, with Nieves winning the four-person race. The seat covers Franklin and Warren counties and part of St. Louis County. Incumbent Republican John Gries-heimer was barred from seeking re-election because of term limits.

Nieves claimed 44 percent of the vote, more than double the votes of Stratman. Nieves will face Democrat George Weber in the November election.