The elite Brooklyn private school teacher accused of catfishing teens for child porn voluntarily enrolled in a sex offender treatment program before his shock arrest, his lawyer revealed in a fiery probation hearing Monday.

Winston Nguyen — a former “Jeopardy!” champion hired to teach at the swanky Saint Ann’s School — narrowly escaped going back behind bars during the hearing over whether he violated his probation in a past conviction for stealing more than $300,000 from an elderly couple.

“My concern here is the allegations of him preying upon the most vulnerable citizens,” an animated Judge Josh Hanshaft said during the Manhattan court hearing.

“First it was the elderly, now it’s children.”

Hanshaft threatened to jail Nguyen before he instead imposed strict probation conditions that effectively confine him to a Harlem apartment — a decision made because of a potential plea deal in the new case.

“The allegations of the fact are that he’s reaching out to vulnerable children on a sexual basis. That’s concerning to me,” the judge said.

After the hearing, Nguyen’s attorney Frank Rothman could be heard in the hallway saying: “F–k, that was close” — alluding to his client almost getting locked up on the violation.

Rothman revealed during the proceeding that Nguyen enrolled in the “Mustard Seed Program” two months ago at the recommendation of his therapist, and prior to his July arrest on the child porn charges.

The program is for “treatment of individuals who have committed sexual offenses,” according to its website.

When asked by the judge why Nguyen voluntarily enrolled, Rothman said it was for “self awareness.” His private therapist recommended it and it had nothing to do with the impending Brooklyn case, Rothman contended.

Nguyen worked as a math teacher at Saint Ann’s School in Brooklyn Heights before he was cuffed in front of students in June — an arrest that saw prosecutors quickly cut him loose as they shored up their case.

He surrendered to authorities July 25, when prosecutors leveled a 30-count criminal complaint accusing him of posing as a teenager on Snapchat, engaging in hundreds of sexualized chats with kids as young as 13 and trolling them for nudes and videos of sexual performances.

At least six youngsters who attended an exclusive cadre of four Brooklyn private schools — including Saint Ann’s — were victimized by Nguyen, prosecutors said.

Since the accusations, Nguyen’s hire at Saint Ann’s has come under fire from the family of the now-deceased elderly couple who hired him as a home health aide, only to have him use their credit cards as a personal piggy bank.

Nguyen had served a four-month jail sentence in 2019 for the theft.

“It’s incredible to me that no one did their due diligence,” the couple’s son exclusively told The Post last week about Saint Ann’s hiring the deceitful ex-con.

Nguyen’s child porn arrest also raised questions about whether he violated his probation, which led to the Monday hearing.

Hanshaft, the judge, ordered Nguyen confined to an apartment he shares with two roommates along Madison Avenue in Harlem.

He also imposed strict electronic monitoring conditions that limit Nguyen from using a cellphone or computer unless it’s for his twice-a-week virtual therapy.

Nguyen must also report to probation weekly and continue with the Mustard Seed program, Hanshaft said, warning any missed appointments will spell trouble. 

“If you have any complications, you’ll be waiting inside of a cell,” Hanshaft told Nguyen. “Do you understand that?”

Nguyen didn’t say anything after the hearing, but he was seen reading a hardback copy of R. R. Martin’s “Fire & Blood” while waiting for his case to be called.

His attorney said a plea deal in the catfishing case could arise if authorities confirm that they found inappropriate materials on the ex-con’s devices.

“If the goods are there, he’s going to plead guilty,” Rothman said. “It’s not like it’s someone else’s phone.”