New York: It began in Westchester County with the arrest of a police chief who was teaching classes about sexual abuse at a Roman Catholic church. The investigation soon swept up many others who were swapping files of children forced into explicit sexual acts — two registered nurses, a Brooklyn rabbi, a New York City police officer, a paramedic and a Boy Scout leader.

All told, 71 people — 70 men and one woman — were taken into custody in the New York City area in recent months on charges of possessing, producing or distributing child pornography, the federal Department of Homeland Security announced on Wednesday at a news conference in Manhattan attended by four New York district attorneys.

“The professional backgrounds of many of the defendants is troubling,” said James T. Hayes Jr., a special agent in charge of New York’s Homeland Security Investigations, an arm of the department’s Immigration and Customs Enforcement agency. “We can no longer assume that the only people who would stoop to prey on children are unemployed drifters.”

Two of the other suspects were an airline pilot and an architect.

Homeland officials said the investigation, named Operation Caireen after a Celtic goddess known for protecting children, was the largest-ever in the New York area, encompassing all five boroughs of the city; Putnam, Rochester and Westchester counties north of the city; and New Jersey. The largest number of suspects, 23, came from Queens.

But the so-called peer-to-peer file-sharing network that investigators uncovered included 3,000 consumers of child pornography, including 150 Internet Protocol addresses in the New York area, officials said. Tens of thousands of sexually explicit images were traded. The customs agency was made the lead enforcer of child pornography cases given that most such material originated in Europe and Asia, officials said, although all of those held in the inquiry were Americans.

District Attorney Daniel M. Donovan Jr. of Staten Island said that in the images and videos implicated in the arrests, children were raped and sexually assaulted by adults.

The peer-to-peer file sharing programme allows users to swap music, photos and videos over the internet with relative anonymity. Cyrus R. Vance Jr., the Manhattan district attorney, said those accused were able to trade videos or photographs of children having sex “like one might collect and trade baseball cards.”

The investigation began after agents, using software available to law enforcement, were able to trace files of child pornography to an IP address on a computer used by Brian Fanelli, 54, who in January was the police chief of Mount Pleasant, New York. He was charged in federal court in White Plains with possession of child pornography, which carries a maximum prison term of 10 years and a $250,000 (Dh918,200) fine.

Until October, Fanelli had been teaching children in religious classes at a Catholic church in Shrub Oak, New York, how to be alert to sexual abuse, covering topics like improper touching and the pitfalls of social media devices. His lawyer, Susanne Brody, has declined to comment on his case.

In March, Homeland Security Investigations agents arrested Samuel Waldman, 52, a teacher at a Jewish girls seminary, at his home in Brooklyn. The agents said he had admitted downloading three short films, including one depicting a young girl being raped. If convicted on the federal charges of possession, he faces a maximum sentence of 20 years in prison and a fine of $250,000. Waldman told News 12 of Brooklyn at the time that the accusations were false and hurtful.

Other arrests included Kenneth Gardner, a registered nurse at Westchester County Medical Centre, who was charged with possession and promoting a sex performance by a child younger than 17; Eduardo Salcedo Urzola, an au pair in Brooklyn, charged with possession; Jonathan Silber, a boy scout leader and Little League coach in Suffern, New York, charged with possession; Yong Wu, in his early 30s, a New York police officer since 2012 who lives in Queens, charged with possession; and Aaron Young, a paramedic in Queens, also charged with possession.

The sole woman was identified as Lori Bauer, of Hunterdon County, New Jersey. She was accused of having produced a sex video with her young son. One of the men arrested, Richard A. Acevedo, 47, of Queens, had previously been convicted of attempted rape of a 10-year-old and was a listed sex offender.

Wu’s lawyer, Thomas A. Kenniff, said in an interview, “I hope people will respect the presumption of innocence and avoid a rush to judgement.”

“My client is a veteran of the wars in Iraq and Afghanistan,” Kenniff added, “and there’s lot more to his life than these allegations.’’