David M. Boutin, 42, of Roy Street, was arrested Friday after a patrol officer discovered him with the boy in Boutin's 2010 Toyota Corolla. The vehicle had been parked on a utility access road on LIPA property north of Route 25 in Shoreham, police said.
Police said the Seventh Precinct officer happened to be in the area searching for a stolen dirt bike.
Prosecutors have also charged Boutin with having sex with the boy in Wading River sometime between April 15 and May 31.
"The charges are horrific to say the least," Judge G. Ann Spelman said at Boutin's arraignment Saturday in First District Court in Central Islip.
Assistant District Attorney Tanya Rickoff said Boutin "did state he was involved in sex acts with the victim" in an interview with investigators. Further details were not immediately available.
Boutin, a financial planner for two years, was ordered not to have any contact with the boy.
Spelman assigned Boutin a Legal Aid attorney after the defendant told her he and his wife earn a total of $50,000 a year.
Two people who identified themselves as Boutin's relatives declined to comment outside the courtroom.
A neighbor, Craig Varsallone, said he was "sickened" by the allegations. "I would wave to him as he drove past like he was a normal guy, a normal husband, but this is not normal," Varsallone said. "It's alarming."
Boutin is being held in jail in lieu of $10,000 cash bail. He faces up to 14 years in prison if convicted of two counts of engaging in a criminal sex act.
Police ask anyone with information about Boutin to call the Seventh Squad at 631-852-8752 or Crime Stoppers at 800-220-TIPS.