Rabbi Yosef Kolko, 39, met the boy in 2007 at religious school-run summer camp in Lakewood where he was a counselor. The boy was 11 at the time, and authorities say abuse continued until early 2009.
Kolko has denied the charges, which include sexual assault and child endangerment.
The boy's father, also a rabbi, testified Thursday that during a car ride back from the boy's therapist's office, his son said Kolko had sexually abused him.
The father said he had talked to the boy a few months earlier about sexual abuse in "general terms" after suspecting that the boy may have been abused; the father did not say why he felt that way. His son, he said, had a "big sense of loyalty" to Kokol.
The morning after his son said he was abused, he said, he called Kokol. The two met and the father told Kokol he needed to attend therapy and stop working with children. The father wanted to bring the matter to a group of rabbis who had "experience dealing with these issues," he said, and did not intend to make the allegations public. The father recorded the conversation at his wife's urging.
The father said Kokol did not dispute the allegations, and the two went to the home of a prominent Lakewood rabbi, where the father said Kokol was contrite and looked "close to tears." The father said the rabbi took the allegations seriously.
The Associated Press generally does not identify accusers in sex crime cases and is not naming the father to protect the son's identity.
Kokol, who was single, was concerned that the allegations might make it difficult for him to be married, the father testified. Kokol asked whether the father would dance at his eventual wedding and the father said yes.
The boy's father wanted to bring the matter to a rabbinical court. But after a few months he was unsatisfied with how the case was being handled and that Kokol was still teaching. After hearing Kokol was planning to return to the summer camp, the father called the head of the camp and Kokol, who told him to talk to a Brooklyn rabbi.
"I was more concerned that he was still at his jobs," the father said. "And I felt that children are being endangered."
Finally, the father decided to bring the case to prosecutors.
"Going to law enforcement is not, at this time, common within the Orthodox Jewish community. Even when it's necessary it's considered unusual," the father testified. "Particularly with some people who might believe that the alleged molester is innocent would give the person going to law enforcement a very hard time.'
Prosecutors said the family was ostracized by the Orthodox Jewish community. A flier was circulated in Lakewood, a community with a large Orthodox Jewish community, saying the boy's father had made a mockery of the Torah and committed a "terrible deed" by taking the case to state prosecutors, the Asbury Park Press reported.
The family has since moved to Michigan. Ocean County Prosecutor Joseph D. Coronato said he commended the victim and his family for coming forward.
"It is my hope that through this case, Ocean County's Jewish community will find comfort in seeking our help and confidence in the justice system now and into the future," he said.
The boy's former therapist also testified Thursday, saying that the boy told her in late 2008 he no longer needed help with his social skills because he had made a new friend, Rabbi Kolko.
"He's my best friend. He's the only one who understands me," Dr. Tsipora Koslowitz recounted the boy telling her.
The boy took the witness stand Wednesday on the first day of the trial, testifying how he wanted to remain close to Kolko, even though his actions made him uncomfortable, because Kolko was his friend and he had no friends in school or camp.
The boy described a series of encounters with the rabbi, who would pick him up in his car, including molestation and oral sex and occurring in such locations as an empty classroom, a storage room, Kolko's car and the basement of a synagogue, the newspaper reported.
