(CNN) It's a case so mysterious that it borders on preposterous: A US senator allegedly tackled by a neighbor while mowing his lawn, an attack so vicious that Rand Paul ended up with six fractured ribs and bruises to his lungs that made it hard to breathe.

There were no known witnesses as Rene Albert Boucher, an anesthesiologist and former colleague who has lived next door for 17 years, allegedly blindsided Paul last Friday by tackling him and throwing him to the ground. The only potential motive that emerged from interviews with a neighbor was that the two men had a long-running feud over leaves and lawn clippings along the property line they share.

But other neighbors find that inconceivable, describing the Pauls as welcoming neighbors with trim and tidy landscaping. And on Thursday, a senior adviser to the senator said, "The Pauls have had no conversations with (Boucher) in many years."

"The first 'conversation' with the attacker came after Sen. Paul's ribs were broken," Doug Stafford said in a statement. "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."

Lidija Loik described Rand and Kelley Paul as "great neighbors" and "lovely people" who welcomed her to the neighborhood when she moved in a few years ago from Canada.

"I don't understand why it happened, or really what happened," Loik said in a telephone interview. "Their home is always open to new and old friends. ...God love them, I mean, they're very busy people, and they're very active in their community. Their home is fantastic. I wouldn't have a problem in the world with it."

Loik said she never heard about any issues related to the Paul-Boucher property line or saw anything amiss with the Paul property.

"If I lived next door to them, I'd be pleased as punch," Loik said.

Not guilty plea

Boucher pleaded not guilty Thursday to misdemeanor assault during an arraignment in Bowling Green, Kentucky. In an interview with CNN, Boucher's attorney, Matthew Baker, said his client regrets the incident.

"If he had to do it over again, I can assure you it would have been handled much more diplomatically," Baker said.

He insisted the incident was not politically motivated.

"This has absolutely nothing to do with any politics, any liberal vs. conservative or Republican versus Democrat," he said. "It's just not about that."

Baker added that he and Boucher recently met with US Capitol Police. A Capitol Police spokesperson said she would not comment "on ongoing investigations."

In interviews this week with more than a dozen GOP strategists and Paul donors, most were mystified by the strangeness of the incident. They mulled how such a brutal event could unfold between two slightly-framed men, which underscores the severity of the attack. Some found it difficult to believe that a property dispute could lead to that kind of violence.

Neighbor Jim Skaggs, who was the developer for the neighborhood known as Rivergreen years ago, told CNN that there has been a "long-running disagreement" between them over property maintenance. He also noted that Paul did not like the rules of the property when they were first explained to him.

"He believes in less restrictions on property rights. He has strong beliefs on this subject," Skaggs said. "He had to be told very sternly that he needed to follow the rules and restrictions. He did not do anything wrong. But he had to be told sternly to follow the rules. He did not like the rules."

Skaggs said he "very much likes" both men, though he noted that Paul "is a very different character than most people."

"He's a deep believer in his own thoughts," Skaggs said. "And he believes his own thoughts are right -- and they are right 100% of the time."

That is the same, sometimes cantankerous, attitude that Paul displayed in Washington during fights over civil liberties, health care and taxes.

"Can you imagine living next door to that guy?" said one congressional colleague who has regularly tangled with Paul over policy. "I'm pulling for the neighbor."

When pressed Thursday to explain the motive, Boucher's attorney said, "I'm saying we should believe" Skaggs.

One GOP strategist said he was mystified by the idea that a former anesthesiologist — someone who dealt with life-and-death situations and had little margin of error in his practice — would allegedly tackle a fellow doctor and cause such severe injuries.

'Weirdness of the story'

"I think the story is the weirdness of the story. It's about lawn clippings and he crushes ... his ribs?" one GOP strategist said incredulously. "That's the story?"

Another GOP strategist questioned whether the "coastal elites," particularly reporters, were failing to understand "the leaf blower wars that take place all across Middle America."

The senator's recovery will be slow; advisers initially speculated it might take weeks or months. But Senate Majority Leader Mitch McConnell, a fellow Kentuckian, said Republicans hoped to welcome him back to Capitol Hill next week.

Paul's advisers have refused to get into the details of the dispute. But they have underscored that the incident that led to the injuries -- six fractured ribs, including three displaced ribs, and lung contusions -- was a serious, criminal matter involving state and federal authorities.

On Wednesday, Paul released a new status report.

"I appreciate all of the support from everyone. A medical update: final report indicates six broken ribs & new X-ray shows a pleural effusion," he tweeted.

I appreciate all of the support from everyone. A medical update: final report indicates six broken ribs & new X-ray shows a pleural effusion — Senator Rand Paul (@RandPaul) November 8, 2017

Baker, Boucher's Bowling Green-based attorney, sought to downplay the incident earlier this week, calling it an "unfortunate occurrence." Baker said Paul and Boucher worked together when they were practicing physicians in Bowling Green. After suffering from a neck injury, Boucher patented a therapeutic vest for people with back pain. In a divorce filing initiated in 2008 when Boucher was 49, his then-wife said he was out on disability as a result of a bicycle accident. (Court filings from 2010 say they were trying to sell their Rivergreen property at that time.)

"We sincerely hope that Sen. Paul is doing well and that these two gentlemen can get back to being neighbors as quickly as possible," Baker said in a statement.