For years, Marc Karun unnerved neighbors in the small Maine town where he lived in a log home that was surrounded by acres of thick woods and couldn’t be seen from the road.

The Connecticut native had shown up in Stetson, a Penobscot County community of roughly 1,200 people, in 2013.

Right away, residents told the Bangor Daily News, he began to exhibit peculiar behavior. He would stand at the top of his driveway and salute passing drivers for no apparent reason, show up at town meetings to make snarky comments, and walk around with a blank stare that left some uneasy. It was well known that he was a lifetime registrant on Maine’s sex-offender registry, with an anonymous vandal painting the word “pedophile” in red paint on the road outside his home one summer.

So when the white-haired 53-year-old man was arrested on Wednesday for the brutal 1986 killing and sexual assault of an 11-year-old girl, residents weren’t exactly shocked to see yellow crime-scene tape blocking off his long driveway.

“I’m not surprised,” Millard Butler, a town selectman who lived a little over a mile down the road, told the Daily News. “He always acted kind of weird anyway.”

Maine officials disclosed Friday that authorities seized 88 rifles and handguns that Karun illegally possessed at the Stetson house, the Associated Press reported. After Karun’s arrest police obtained a search warrant that led to the discovery of the guns, which he is prohibited from having because he is a convicted felon, District Attorney Marianne Lynch said.

Karun was charged with illegally possessing guns, but the charges were dropped to allow him to be extradited, said Lynch, who is district attorney for Penobscot and Piscataquis counties.

Karun agreed not to fight extradition during a court appearance in Bangor on Friday. Police in Norwalk, Connecticut, said they were going to drive Karun later in the day to Norwalk, where he will be booked and detained until a court arraignment on Monday.

Marc Karun Photo courtesy of Penobscot Sheriff’s Office via Norwalk Police Department

Detectives in Norwalk had harbored suspicions about Karun for more than 30 years.

On the afternoon of Sept. 23, 1986, Kathleen Flynn left school and began walking home on a paved footpath that cut through a wooded area, the same route that she took every day. Several hours later, her mother called to report her missing. The sixth-grader’s body was found in the woods early the next morning, not far from the path she had taken home and the athletic fields where soccer and field hockey teams had been playing when she disappeared. She had been raped and strangled.

At the time, Karun was living within a few miles of the school. He had previously been convicted of sexual assault and was questioned within weeks of the murder. Though he denied having anything to do with the crime, he also made a bizarre admission.

Four days before Kathleen was killed, he claimed, he had gone to her middle school to “see some teachers.” He described visiting the school’s library and talking with a librarian, and walking around on the same footpath that the sixth-grader had taken, according to a police affidavit obtained by News Center Maine WCSH/WLBZ.

But when police went to the middle school, none of the librarians remembered seeing Karun. The only teachers who recognized his photo were those who knew him as a former student with “serious problems,” according to the affidavit. When questioned about the discrepancy, Karun said that he hadn’t actually been at the school that day.

About eight months before Kathleen was murdered, Karun was arrested on sexual assault and kidnapping charges that were later downgraded after the victim decided that she didn’t want to testify against him in court. Authorities noticed similarities between the two cases, according to court records obtained by the Daily News. Forensic testing didn’t establish a link, but it also didn’t definitively rule out Karun as a suspect.

Kathleen Flynn Photo courtesy of Norwalk Department of Police Services

As police chased down countless leads that turned out to be dead ends, the unsolved murder left the community on edge.

“The kids in school were all terrified, as was everyone in the neighborhood,” Enes Drake, a substitute teacher who lived near the middle school, told the Connecticut Post. “We were all on high alert. The guy was never caught, so we were always looking over their shoulders.”

Detectives would return to Karun again and again in the decades that followed. Two people who knew him – a friend and the victim from the 1986 sexual assault case – separately told police that they also remembered him talking about visiting Kathleen’s middle school. But in the version that they both heard, he had been there on the day of the murder. Still, aside from those comments, nothing directly linked him to the case.

Meanwhile, Karun began accumulating a lengthy rap sheet in Connecticut, including multiple convictions for first-degree sexual assault, according to the Hartford Courant. In 1989, he was ordered to register as a sex offender for life.

As he cycled in and out of prison, police kept trying to crack the case, hoping that advances in DNA technology would eventually lead them to a suspect. Authorities haven’t said yet how they finally zeroed in on Karun, but plan to release more details at a news conference at a later date.

An arrest warrant says that although DNA testing on Karun came back either negative or inconclusive, Kathleen was killed in a similar fashion to four other attacks on females of which Karun was convicted, the Associated Press reported Friday.

The arrest came nearly a year after Kathleen’s father, Jim, died, the Courant reported. In a statement, the family thanked the Norwalk Police Department “for bringing Kathleen’s murderer to justice” and asked for privacy.

Messages seeking comment were left Friday with lawyers who will be representing Karun in Connecticut. Zachary Smith, a Bangor lawyer who represented Karun on Friday, declined to comment on the allegations.

Often, arrests in decades-old cold cases lead to shock and dismay as the suspect’s friends, neighbors, and co-workers learn that the person they thought they knew was hiding a dark secret. In Stetson, that wasn’t the case. Neighbors who asked not to be identified told WABI that they “always got kind of a creepy vibe” from Karun, and were glad to hear that he was in custody.

“He made all of us uncomfortable,” Catherine Fisher, who works as the town registrar and handled Karun’s car registration every year, told the Daily News. “He would come in, and it’s almost like he looks right through you. He didn’t know when to leave.”

Butler, the selectman, recalled that Karun almost always showed up to the town meetings that take place twice a month. At one recent meeting, a woman became uncomfortable because the registered sex offender, who was seated in the front row, kept staring at her through dark sunglasses, he told the Daily News. She asked Butler to stay behind after the meeting ended, and make sure that she got home safely.

“Most of the time, when you hear about someone doing something like this, you think, ‘I guess I knew that person, I didn’t think he was really capable of doing it,’ ” Butler told WCSH. “But in this case, what I’ve seen of him, I’m not surprised a bit. I think he was completely capable of doing something like that.”