Police describe him as a monster — a young Wisconsin man so fixated on a hazel-eyed, 13-year-old girl, that he allegedly shot her parents dead in their home and stole her away, keeping her captive in a wooded cabin for 88 days until her escape.

But by all accounts, Jake Thomas Patterson, the accused abductor-murderer in the Jayme Closs case, was an average, even boring, young man.

The bespectacled 21-year old had no criminal record and shunned social media. He was unknown at the nearest bar and convenience store, and his closest neighbors didn’t know he was around.

Even those who do know Patterson recalled him as too unremarkable for the evil of which he is accused.

“Never in a million years would I have thought Jake would ever do something like that,” Elissa Lisenby, who attended Northwood High School with Patterson, told The Post on Saturday.

“This isn’t the Jake we all grew up knowing,” she said of her quiet, anxious classmate.

“Nobody really knew him like we thought,” former classmate Clinton Rolnik told The Post.

Jayme spent her second night of freedom with her family Friday, according to her aunt, Jennifer Smith.

“Jayme had a pretty good night sleep,” Smith wrote on Facebook Saturday. “It was great to know she was next to me all night. What a great feeling to have her home,” she wrote, adding that Jayme’s parents “can rest at peace.”

Jayme’s grandfather Robert Naiberg said Saturday that no one in the family knew Patterson.

“He didn’t know Jayme, he didn’t know Denise or Jim,” Naiberg said. “(Jayme) don’t know him from Adam. (But) he knew what he was doing. We don’t know if he was stalking her or what. Did he see her somewhere?”

Meanwhile, Patterson remained jailed in Barron County Jail pending a court hearing Monday.

He had been a good student at his Wisconsin middle and high school, classmates said.

Still, he was voted “most quiet” in his 2015 graduating class of 34 students, according to the Journal Sentinel.

He didn’t go to his prom, or to the senior class trip to Florida, classmates told the paper. He was however, on the school’s quiz bowl team.

“I don’t really remember a ton about him,” said former middle school science teacher Kristin Kasinskas

“I don’t recall anything that would have explained this.”

By coincidence, it was at Kasinskas’s home that Jayme would take refuge after fleeing from Patterson’s cabin on Thursday, police said.

“When [Jayme] said the name, I said, ‘I know him — I’ve had that student,” she told the Star Tribune.

“He was a nice kid,” she said. “Quiet kid. Very smart. He didn’t speak out in class.”

He never had a girlfriend that any pal could remember.

“He was always a little awkward,” Rolnik told the Daily Beast.

“I guess just really shy.”

They’d swim together in the nearby river, ride dirt bikes, play video games together, but “nothing crazy,” Rolnik said.

Patterson had made some unsuccessful passes at finding a career — trying the Marines, but dropping out during boot camp, and working three years ago at the same Jennie-O turkey plant as James and Denise Closs, Jayme’s parents, who he’s charged with murdering.

James was 56; Denise was 46.

A company spokesman said that Patterson left the turkey plant after a single day of work, explaining he was moving. Investigators told reporters they don’t believe Patterson had any contact there, or elsewhere, with the Closs family.

Aside from these forays into the working world, Patterson was just basically “sitting at home doing nothing, as usual,” since graduating, Rolnik said.

If anything, the likely Patterson to get into trouble was his big brother, who pleaded no contest in 2013 after being charged with sexually assaulting a 15-y-o girl when he was 18, according to multiple reports.

The brother also has a felony marijuana conviction for which he served 30 months probation.

But it appears the brother did not live with Jake in the remote, wooded cabin in Gordon, Wis., 80 miles north of Barron, where Jayme was abducted. Investigators say they believe Patterson acted alone.

Patterson’s mother and brother did use social media, according to since deleted posts cited by Heavy.com.

The mother’s featured religious and inspirational posts. The brother’s indicated he had moved to Colorado, where he was working at a Subway. Both have removed their postings.

Patterson seems to have picked Jayme out of thin air, police said after his arrest.

“Nothing in this case shows the suspect knew anyone at the Closs home or at any time had any contact with anyone in the Closs family,” Barron County Sheriff Chris Fitzgerald told reporters.

But this was no spur-of-the-moment attack.

Once he set his sights on Jayme, Patterson planned her kidnapping down to the most minute detail, even shaving his head so that he wouldn’t leave DNA-testable hair at the Closs home, authorities contend.

There, sometime after midnight on October 15, he arrived, armed. Investigators believe he used a shotgun to blast his way through the front door.

A 911 dispatcher received a call from Denise’s cell phone just before 1 a.m., but could only hear the sound of people yelling before the line went dead.

Arriving cops found James and Denise Closs dead inside, and Jayme vanished.

The middle schooler wound in a secluded cabin in the woods of Douglas County that Patterson’s parents had purchased before their 2007 divorce.

Nearly three months after her abduction, on Thursday at 4:30 p.m., while Patterson was out of the cabin, Jayme managed to flee. She calmly ran up to neighbor Jeanne Nutter, who was out walking her dog.

Jayme was skinny, disheveled and wearing pants and shoes that didn’t fit — but Nutter knew immediately who she was.

“The first thing she told me was, ‘I’m lost and I don’t know where I am and I need help,’” Nutter told the Star Tribune.

In the end, it was Jayme, through her description, who’d lead police to capture her captor, investigators said.

Patterson was arrested just eleven minutes after Jayme approached the dog-walking neighbor. Police say he was driving near the cabin — looking for Jayme.

The cabin had been in the name of Patterson’s father, Patrick. Then, days after Jayme’s abduction, ownership passed to a credit union, according to the Associated Press, which said the home was appraised at $79,300.

Investigators said they found more than one gun inside, including a shotgun consistent with the type of gun used to kill James and Denise Closs.

Additional reporting by Dean Balsamini and Anthony Izaguirre, with Post Wires