— A man who allegedly attacked Sen. Rand Paul (R-Ky.) in his yard last week and broke at least six of his ribs pleaded not guilty to a misdemeanor assault charge Thursday.

Rene Boucher, 59, a retired anesthesiologist, appeared in Warren County District Court on Thursday morning with his attorney. He faces a possible 12-month sentence and a $500 fine if he is convicted of fourth-degree assault, according to County Attorney Amy Milliken.

It remains unclear whether more serious federal and state felony charges are on the way, with Kentucky State Police and FBI investigations continuing.

New details emerged Thursday about the day of the attack, when five hours apparently elapsed from the time police responded to Paul’s home to the moment they arrested Boucher.

But the mysterious nature of the attack remained unsolved. Police, and Paul himself, were unaware initially just how serious his injuries were — and Paul did not immediately seek medical attention, police said. In addition, no new evidence emerged Thursday to help explain a motive for the altercation.

Rene Boucher, center, appears in court for an arraignment hearing with his attorney Matt Baker, left, on Thursday. (Austin Anthony/DailyNews/AP)

“During the initial investigation, all indications pointed toward a minor injury to the Senator,” Trooper Jeremy Hodges, a spokesman for the Kentucky State Police, said in a text message, explaining why it took five hours to arrest Boucher. “He had not been checked by a doctor. We can’t arrest for a misdemeanor assault without a warrant in Kentucky unless it’s domestic violence-related or it happens in an officer’s presence.”

Paul’s Senate office offered no comment Thursday.

Fourth-degree assault is the most serious charge prosecuted by the Warren County attorney. More serious state charges would come from Commonwealth’s Attorney Christopher T. Cohron. Federal charges, in turn, would fall to the U.S. attorney’s office in Louisville. Stephanie Collins, a spokeswoman for the U.S. attorney’s Office in Louisville, offered no information on the likelihood of a federal prosecution.

Matthew J. Baker, Boucher’s attorney, said that his client had not been home since the incident. Baker also told reporters that the incident “was unequivocally not about politics.” Earlier in the week, he had characterized the incident as “a very regrettable dispute between two neighbors over a matter that most people would regard as trivial.”

Doug Stafford, a senior adviser to Paul, on Thursday disputed Baker’s characterization of the incident.

The senator “was vigorously assaulted by someone in his neighborhood. This is a serious criminal matter involving serious injury, and is being handled by local and federal authorities,” Stafford said in a statement. “As to reports of a long-standing 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.”

A political motivation would drastically increase the likelihood of federal charges under a law that makes it a crime to assault a member of Congress “on account of the performance of official duties.” That charge comes with a possible sentence of eight years — 20 if a weapon is involved — as opposed to the 12-month sentence and $500 fine Boucher faces.

The potential for federal charges are “a concern. I hope that doesn’t happen,” Baker said. But based on his research and understanding of the case, he does not think federal charges will be warranted.

Boucher has no criminal history, and prosecutors are not aware of any previous incident between the two men, Milliken said.

The courtroom was packed for the arraignment with out-of-town reporters there to see for the first time the man who allegedly attacked Kentucky’s junior senator, who also ran unsuccessfully for president in 2016.

The scene was so out of the norm for locals that the judge and prosecutor both pulled out their cellphones to take pictures of the large crowd, marveling that they’d never seen the courtroom so full and possibly never will again.

According to Baker, Paul has retained personal injury lawyer Thomas N. Kerrick of the Kerrick Bachert firm in Bowling Green. A message left at Kerrick’s office had not been returned as of late Thursday morning, and a receptionist said the attorney was traveling.

Boucher often frequented Spencer’s Coffee, a popular spot on the square in Bowling Green, said barista Ben Fox-Ezell, 29, of Auburn, Ky. Boucher’s habit of wearing a beret and ascot made him conspicuous, Fox-Ezell said. Boucher often brought a chessboard and played with a friend.

“He’s always really nice and super soft-spoken,” said Fox-Ezell, who added that while Boucher used to talk with staff and customers, he never heard Boucher discuss politics.

Dominic Lanphier, 51, of Bowling Green and a mathematics professor at Western Kentucky University, does not know either man but noted t hat it is “peculiar” that the reported details of the attack have shifted from Paul suffering only minor injuries, to revelations that he has several broken ribs and is unable to travel to Washington.

“It’s one of those things that I think you only get the whole story as it leaks out bit by bit,” Lanphier said.

O’Keefe reported from Washington.