The neighbor who tackled Sen. Rand Paul has agreed to plead guilty to federal charges stemming from the November 3 assault in their gated community in Bowling Green, Kentucky. The attack left the senator with six broken ribs.

Rene Boucher, a 59-year-old retired doctor, will be charged with assaulting a member of Congress, which is a federal felony offense. Prosecutors also cleared up some of the mystery that had been swirling since the incident: The case does, indeed, appear to be yard-related — specifically, about the placement of a brush pile.

Paul had just finished mowing his lawn on November 3 when Boucher allegedly saw him “stack brush onto a pile near the victim’s property,” according to the US attorney’s office for the Southern District of Indiana. Boucher told prosecutors he’d “had enough”:

Boucher ran onto the victim’s property and tackled the victim. As a result of this assault, the victim suffered multiple fractured ribs and subsequently contracted and required medical attention for pneumonia. Boucher admitted the assault but denied it was politically motivated.”

The attack on Paul had previously been shrouded by intrigue. Boucher’s lawyer had claimed after the altercation that it sprung from a “trivial dispute.” Media reports painted a picture of a long-simmering property dispute between the two men, possibly over landscaping or yard waste. Other reports speculated on a possible political disagreement. Based on Boucher’s statement to prosecutors, the tussle did have more to do with property than politics.

Boucher had originally been charged with misdemeanor assault, to which he pleaded not guilty in November. It is unclear what will happen with that charge, but Boucher’s attorney, Matthew J. Baker, told the New York Times he expects it to be dismissed with Boucher’s guilty plea to the federal offense. The federal charges are significantly more serious, and carry a sentence of up to 10 years in prison and a $25,000 fine, according to the US attorney’s office.

Boucher will likely avoid the maximum sentence with his plea deal. No date has been set yet, but the Washington Post reports that prosecutors will recommend he serve a 21-month sentence, based on court documents.

“Assaulting a member of Congress is an offense we take very seriously,” US Attorney for the Southern District of Indiana Josh J. Minkler said in a statement. “Those who choose to commit such an act will be held accountable.”

Paul returned to the Senate a little more than a week after Boucher’s violent assault. Earlier this month, he appeared on CBS’s Face the Nation and said he was in “a living hell” for weeks after the assault. “Couldn’t get out of bed without assistance,” he said. “Six broken ribs, damage to my lungs, two bouts of pneumonia. It was really a tough go of it.”

Paul was mowing his lawn when a neighbor tackled him

Paul had reportedly just finished mowing his lawn on November 3 at his home in Rivergreen, an upscale gated community in Bowling Green, when Boucher tackled him from behind, “forcing him to the ground and causing pain,” reported NBC News, which obtained the criminal complaint.

Paul was wearing protective earmuffs to muffle the sound of the mower, two sources told the New York Times, which prevented him from hearing Boucher’s approach. (Paul told US Weekly in a 2015 interview that he loved working in his yard and that “mowing the lawn is very therapeutic for me.”)

NBC News reported that Paul managed to get Boucher off him, after which the two “exchanged words.”

Here is a repost of arrest warrant for Rand Paul incident. This one has redactions. Sincere apologies about missing that last time pic.twitter.com/eDMEOy7hGs — Sam Stein (@samstein) November 6, 2017

Jim Skaggs, a neighbor and one of the developers of the Rivergreen gated community, speculated to GQ that Boucher charged Paul from the street:

From that direction, Paul's yard slopes steeply downward, toward the lake at the rear of his property. Barreling downward about 30 degrees, this imagined path would increase the force of a running tackle, perhaps explaining how a man of Boucher's diminutive stature—an acquaintance of the two men estimates that they both stand five-foot-six and weigh about 140 pounds—could do so much damage.

Boucher, who admitted to tackling Paul in the criminal complaint, was initially charged with one count of fourth-degree assault, and was released from custody on $7,500 bond. He pleaded not guilty during a court appearance on November 9.

State police said Paul had sustained “minor injuries” in the first reports after the incident. But in the weekend after the attack, Paul’s staffer, Doug Stafford, said in a statement to the Washington Post that the fractured ribs — three of which were partly or completely cracked — had bruised at least one of Paul’s lungs.

“This type of injury is caused by high velocity severe force,” Stafford said. “It is not clear exactly how soon he will return to work, as the pain is considerable as is the difficulty in getting around, including flying.” He described the injuries as those that could lead to serious and long-term health ramifications.

The senator clarified his condition for the first time on November 8. In the tweet, Paul said he broke six ribs (it had originally been reported as five) and suffered from a pleural effusion, which is a buildup of fluid in the lining around the lungs.

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

Why did Boucher attack Paul?

Boucher is a retired doctor who practiced as an anesthesiologist and pain specialist; his medical license expired in 2015. According to a Bowling Green Daily News report from 2005, Boucher also invented the Therm-a-Vest, a device that attaches by Velcro and heats up to help with chronic back pain. It was featured on QVC.

The two men, who live next door to each other and previously worked together as doctors, may have argued about politics in the past. Jim Bullington, who served on the city commission and was acquainted with both Paul and Boucher, told the Post that the men are political opposites and have had “heated discussions” about health care.

Boucher’s attorney, in a November 6 statement, denied that the attack had anything to do with politics, and instead called it a “regrettable dispute between two neighbors over a matter that most people would regard as trivial”:

Senator Paul and Dr. Boucher have been next door neighbors for 17 years. They are also prominent members of the local medical community and worked together when they were both practicing physicians. The unfortunate occurrence of November 3rd has absolutely nothing to do with either’s politics or political agendas. It was a very regrettable dispute between two neighbors over a matter that most people would regard as trivial. We sincerely hope that Senator Paul is doing well and that these two gentlemen can get back to being neighbors as quickly as possible.

Boucher has now denied to federal authorities that the attack was politically motivated.

But even before that, some sort of property dispute had already begun to trump politics as a possible motive for the attack. Jonathan Martin of the New York Times has reported that this “trivial” issue might have something to do with some mysterious plant-related problems; sources gave multiple landscape-based reasons that ranged from a new sapling to yard clippings to unraked leaves.

Two Kentuckians tell me Rand’s neighborhood fracas stemmed from a dispute over some sort of planting or flora issue around the properties — Jonathan Martin (@jmartNYT) November 6, 2017

An unnamed neighbor also told CNN that these lawn-based tensions had long been simmering, though Rob Porter, a friend of Paul’s, said the senator told him he hadn’t spoken to Boucher in years. “He is still unsure why he was attacked,” Porter said. “I don’t know if he knows why he was attacked.”

Rand Paul and neighbor have been sparring over yard waste and leaves blown on each other's lawns for years, a neighbor tells @DrewGriffinCNN — Manu Raju (@mkraju) November 6, 2017

Paul added more intrigue by retweeting two stories that cast doubt on the “landscaping dispute” story, both of which originated in conservative news outlets, the Washington Examiner and Breitbart.

Stafford, Paul’s chief strategist, also knocked the idea of a Paul-Boucher dispute. “The first ‘conversation’ with the attacker came after Sen. Paul's ribs were broken,” he said. “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.”

GQ, in a story published November 20, dug into questions of politics and lawn care. The report, speaking to neighbors and acquaintances in the Bowling Green community, pointed at two men with a clash of personalities that played out in a property dispute that left Boucher festering in anger and frustration.

According to GQ, Boucher faced some personal setbacks in recent years, including a divorce in 2008. He had tried to sell his house in the gated community soon after, but he had trouble finding a buyer. Boucher ended up staying put after a deal fell through in 2012.

Boucher, according to neighbors, was a stickler when it came to his property. He paid professionals to tend to his yard, but his neighbor, Paul, did his own landscaping. And it may not have been up to Boucher’s standards. “He had his yard sitting at a beautiful two-and-a-half, three inches thick, where Rand cuts it to the nub,” Bill Goodwin, a Bowling Green resident who knows both men, told GQ.

Paul, hobbyist mower that he is, also may not have been the most attentive at the post-yard work cleanup. Boucher fretted over Paul’s grass clippings that ended up in his yard, confronting the senator and complaining to the neighborhood association. “I've asked him and I've asked him and I've asked him,” Goodwin remembers Boucher complaining about the senator’s lawn etiquette. “How long can you sit there taking someone plucking a hair out of your nose?”

Either way, neighbors in the upscale neighborhood weren’t thrilled about how the incident brought scrutiny on their neighborhood. One person, talking to GQ, called both the attacker and the victim “two little shits.”

It looks like the “yard waste” case is closed

Paul, left bloodied and bruised after the attack, returned to work in the Senate shortly after the assault. He told Face the Nation earlier in January that “each day I feel a little bit better. This last month I’ve been doing better.”

Boucher’s plea agreement will likely put an end to the speculation about the attack, too. Baker, Boucher’s attorney, said in a statement to the Post that Baker “continues to be very regretful and very remorseful” and added that his client is “is looking forward to gaining some closure on this.”

Nevertheless, the attack on Paul also adds to questions over the security of lawmakers, as the Wall Street Journal points out. In June, a gunman opened fire at a GOP congressional baseball practice, injuring four people, including House Majority Whip Steve Scalise, who was severely wounded. Paul, who was at the practice that day, escaped unharmed.