The man accused of tackling U.S. Sen. Rand Paul outside his home made his first court appearance Thursday on a misdemeanor assault charge.

Rene Albert Boucher, 59, appeared in Warren District Court with his attorney, Matt Baker, and entered a not guilty plea to a count of fourth-degree assault.

On a docket featuring several dozen misdemeanors, traffic cases and defendants who had spent the previous night in jail, Boucher’s case was called first by Warren District Judge Brent Potter.

Boucher, wearing a muted blue suit, showed no emotion and remained silent during the arraignment.

Potter set a pretrial conference for Nov. 30.

Boucher and Baker left the Warren County Justice Center without speaking to reporters, who gathered in significant number for the hearing.

Paul, Kentucky’s junior senator and a Republican presidential candidate in 2016, wrote Wednesday on his official Twitter account that he has six broken ribs and a pleural effusion – defined as an unusual amount of fluid around the lung – following the incident Friday afternoon outside his home. The latest update from the senator indicates that the injuries he suffered were more extensive than an earlier disclosure from his staff that Paul had five fractured ribs, with three displaced fractures.

Paul’s injuries were initially characterized as “minor” by the Kentucky State Police in a news release the agency issued the day after the incident.

Warren County Attorney Amy Milliken said KSP and the FBI continue to investigate the matter, and it remains possible that the charge against Boucher may be amended because of the extent of Paul’s injuries.

“The investigation is ongoing, it has not concluded and we are cooperating with all authorities,” Milliken said after the arraignment.

Paul was not in the courtroom Thursday.

Milliken said her office has kept Paul, an ophthalmologist, apprised of the court proceedings through the FBI. She declined to comment on a possible motive for the incident.

“We’re going to let that play out in court,” Milliken said.

Boucher is a retired anesthesiologist and a neighbor of Paul’s in the gated Rivergreen subdivision east of Bowling Green. He has been a registered Democrat since at least December 1998, according to the Warren County Clerk’s Office, but Baker has said that politics did not figure into what he characterized as the “regrettable dispute.”

Jim Skaggs, who developed Rivergreen and is a member of the Republican Party of Kentucky’s executive committee, told the Daily News that the incident last week was “nonpolitical to my knowledge.” In an interview, Skaggs characterized the incident as “strictly a neighborly dispute” that “may have involved a cleanup of leaves issue.” However, Travis Creed, a friend and neighbor of Paul’s, told the Daily News on Wednesday that reports of a “landscaping dispute” are “erroneous and unfounded.”

Late Thursday morning, Paul's senior adviser Doug Stafford issued a statement reiterating that Paul was the victim of a "blindside" attack.

“Last week Senator Paul was vigorously assaulted by someone in his neighborhood," Stafford said in the statement. "This is a serious criminal matter involving serious injury, and is being handled by local and federal authorities. As to reports of a longstanding dispute with the attacker, the Pauls have had no conversations with him in many years. The first 'conversation' with the attacker came after Sen. Paul's ribs were broken. This was not a 'fight,' it was a blindside, violent attack by a disturbed person. Anyone claiming otherwise is simply uninformed or seeking media attention."

Reached by phone later Thursday, Baker disputed the characterization that Paul was "blindsided" in the incident but did not go into further detail. He acknowledged that the two men had not had a conversation in a "long, long time," and he suggested that the altercation was related to the "issue of property between the two and the maintenance of those respective properties."

"This has all just been very regrettable," Baker said. "I know if (Boucher) could have this to do all over again, he would handle it completely differently."

Baker said he has received an email from Bowling Green attorney Tom Kerrick notifying him that Kerrick will represent Paul on any personal injury claim in the event of the filing of a civil lawsuit.

Fourth-degree assault is a Class A misdemeanor in Kentucky that is punishable by up to 12 months in jail and up to a $500 fine.

Boucher spent nearly 24 hours in Warren County Regional Jail following his arrest. He was released Saturday on a $7,500 cash bond that forbids him from any contact with Paul, his family or offices.

Boucher must remain at least 1,000 feet away from the senator, unless Boucher is inside his home, when the distance is 200 feet, according to court documents. Boucher is not allowed to possess any firearms or weapons and must avoid committing any new offenses under the conditions of his release.

– Follow courts reporter Justin Story on Twitter @jstorydailynews or visit bgdailynews.com.