In the early morning hours of Dec. 13, 2008, the body of Catherine Novak, a recently separated 41-year-old mother of two, was found in what little remained of her burned-down house in upstate New York. She was in the basement, buried under 2 1/2 feet of debris, burned beyond recognition. Two autopsies were performed, and the cause of death remains inconclusive.

The blaze was so ferocious and devastating that it took hours to extinguish, the air so frigid that firefighters had ice in their boots. When it was finally out, almost nothing remained; it was impossible for investigators to find any physical evidence or determine what caused the fire.

Less than one year later, Paul Attila Novak, Catherine’s estranged husband, was living with his two children and girlfriend, Michelle, in Palm Coast, Fla. Paul was working as an EMT — just as he had in New York City — but now he had an extra $800,000, proceeds from homeowner’s insurance and two life-insurance policies on Catherine.

All of this made Catherine’s friends and family suspicious, but nothing more so than his occupation: Who would know better how to kill someone and set an untraceable fire, wiping out any and all physical evidence, than a trained EMT?

Plus, he had to know the local cops weren’t the brightest. After one robbery attempt at the town pharmacy, the owner asked the police — who took over an hour to arrive — if they were going to dust for prints. They were not. “This isn’t TV,” one officer said. “This is Sullivan County.”

For nearly five long years, what happened in the house on 222 County Road 25 has been the main preoccupation of most everyone in Narrowsburg, population 431.

Catherine’s friends believe that Paul Novak got away with murder.

In August 2002, Catherine and Paul moved from their cramped apartment in Queens to a two-story house in the burg by the banks of the Delaware River, taking out a mortgage on the $135,000 property.

Catherine had grown up poor, living with her parents and three older brothers in the same borough, stretched out on the floor in the summer, watching her beloved Yankees on WPIX and wishing that they could afford air conditioning. She wanted more for her children, a big house and a yard and good schools, and Paul agreed.

They had married on Feb. 14, 1997; meeting after Catherine volunteered for an ambulance service, Paul working as a paramedic for Jamaica Hospital. Catherine was attracted to Paul’s confidence; he was a big guy, good-looking, and had a job helping people — something Catherine, ever the volunteer, deeply admired.

In 2002, Paul and Catherine had a daughter, and four years later, a son. They moved upstate, and Paul said he couldn’t make as much money up there but it was fine, he’d stay in the city for work and spend two days a week up in Narrowsburg.

“He would tell her, ‘I picked up extra hours, I’ll be at my mom’s’ — and then he’d swing by his mom’s so she’d see him,” says a confidant. “Everyone knew what was going on” — except Catherine, who refused to see it. “She loved him,” says the friend. “Oh, she loved him.”

“It was all about him, all the time,” says another friend. Paul had his own buddies — other EMTs, big, burly guys who were just like him — and had no interest in getting to know Catherine’s friends, or in socializing with other couples. He’d spend what little money they had on himself, buying the latest gadgets and splurging on a flat-screen TV, all while insulation was peeling off the walls.

Catherine presented herself as capable and together — yet as co-workers and fellow churchgoers came to know her better, they began to see the wife whose husband didn’t really live with her, stuck in disrepair on a back-country road while Paul partied in the city. She always defended him.

Catherine’s friends recall her as ecstatic in early 2007. Paul wanted to renew their wedding vows, she said — it was such a big deal to him and he was so excited. They wanted to believe her, but they all thought Paul was doing it to placate her.

It was like that morning when she came into work — she’d gotten a job at the local summer camp — and announced Paul had just taken out a life-insurance policy on her. It was weird, she admitted — but she did what she always did, warping it into proof of what a good family man Paul was.

Within a few weeks of the vow renewal, Paul told Catherine he didn’t love her anymore, and on those rare nights he returned home, he’d sleep in the guest bedroom. A confidant says she begged him to go to marriage counseling, and he agreed, going twice before telling her, “This isn’t working — I quit.”

One night, at 4 a.m., the phone rang three times, and Catherine picked it up to hear the slurry female voice on the other line. Now she knew. Paul told Catherine it was all her fault, and the affair had been going on for only a few weeks anyway. “It was the semi-classic thing of the husband cheating and saying to his wife, ‘You’re no good,’ so he could justify it,” says another confidant.

Within a week, Catherine had kicked him out, and Paul went to live with his girlfriend, Michelle La France, whom he’d met in 2007 when he was training Michelle to be an EMT. Catherine was devastated, anxious all the time, and one of her friends asked her if she was afraid of Paul. “She made a comment that she was more afraid of the girlfriend.”

On the last day of Catherine’s life, after Paul and Michelle picked up the kids, she was so distraught that she went to visit her church group; she remained so upset that friends took her home.

At 6 a.m. on Dec. 13, a neighbor sat on his front porch, up and across the street, enjoying his cup of coffee and watching what he thought was the sunrise. He realized, a few minutes later, that it was an enormous fire, and ran toward it, even as he found there was nothing he could do.

Paul didn’t attend Catherine’s funeral. Instead, he dropped the kids off at the service and picked them up, and he did the same at the gravesite, walking them up to their mother’s coffin and leaving them with Catherine’s family, making them all come looking for him when it was over.

Not long after, Paul and Michelle had their brand-new life in Florida, happily playing house.

The Narrowsburg fire was written off as an accident — until one fateful night in 2012, when, at a wedding on her own, Michelle had a feeling. She called Paul. “Are you seeing someone else?”

“Yes,” he said.

“I want you out,” she said.

In September of last year, Michelle La France called Sullivan County police, and suddenly the long-dormant case came alive. Michelle said Novak confessed to her that he’d killed his wife and that their friend and fellow EMT Scott Sherwood helped him do it. Paul and Scott had worked as partners for many years as state-certified EMTs out of Jamaica Hospital, responding to 911 calls just as FDNY medics would.

On Sept. 27, cops picked up Scott, and he confessed to everything. His detailed account — which he has since recanted — was found in court documents obtained by The Post.

Scott told police that on the night Catherine died, he drove to Paul and Michelle’s house in Glen Cove, LI, for the express purpose of driving Paul upstate so he could kill Catherine. The two men left their cellphones in the house so they couldn’t be traced, and Paul said he’d been mixing up chloroform to make Catherine pass out. On the way, they stopped at a Walmart in Middletown so Paul could buy a plastic bag and probably duct tape and rope.

Scott asked Paul why he was murdering his wife, and, according to the confession, Scott said it was “so he wouldn’t end up like me,” broke and divorced and forced to “work 80 hours a week and be miserable.”

When they got within a mile of the house, Scott said, Paul had him roll the car into a wooded area. Scott said he waited in the car while Paul walked up toward the house, returning an hour later, wearing scrubs and plastic booties on his feet.

“Paul told me in the car that he went into the basement of the house and disconnected something to make Catherine come down to the basement,” Scott confessed. “He then attempted to make her pass out with the chloroform, but she resisted. He stated that he had to strangle her when it didn’t work. Paul said that Catherine passed out and then he set the house on fire by breaking a gas line. Paul stated that Catherine asked him why he was doing this, and he said that he told her it was for the kids.”

Michelle La France, the woman who made Catherine’s life so miserable, is now the star witness for the prosecution. She declined to comment for this story, though when asked if she was aware the defense is planning to paint her as an unstable nymphomaniac, smiled and said, “I know exactly what they’re trying to do.”

Scott Sherwood and Paul Novak are now represented by a father-son legal team. “I’d like to know who’s paying for Scott’s attorney,” says one of Catherine’s friends.

Scott and Paul are awaiting trial, slated to begin in July, in Sullivan County jail. Paul has been charged with first- and second-degree murder, grand larceny, insurance fraud and arson; Scott with second-degree murder.

Sources for Paul Novak’s defense say they are not concerned. There is no physical evidence of strangulation. They also maintain that there is no way their client could have committed the crime in the time frame laid out by the prosecution. It’s a three- to four-hour drive from Glen Cove to Narrowsburg. The prosecution’s star witness, they say, is nothing more than a woman scorned, and she has enough erratic behavior in her past to discredit her. “They were in the process of amicably resolving their divorce,” says the source. Catherine “didn’t give a s–t that he was living with his girlfriend.”

For a time, Paul and Catherine’s children were living with Paul’s current girlfriend, Kathleen Del Grasso, and are now in the custody of Paul’s mother. Del Grasso maintains Novak’s innocence.

All that remains of Catherine Novak’s home is the red-and-white two-car garage, quaint and barn-like, and a squat brown shed, propped nearly closed by a heavy stone. Wild grass grows where the house once stood.

“Her life goal was to have a home and a family,” says an intimate. “That was part of her fascination with Paul.”

Additional reporting by Candice Giove and Julie Kay