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 Homeland Security Investigations. “We can no longer assume that the only people who would stoop to prey on children are unemployed drifters.” Other suspects include an airline pilot and an architect.

Federal 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, Rockland and Westchester Counties north of the city; and Hunterdon County, N.J. The largest number of suspects, 23, came from Queens.