New Haven (AP) - Federal authorities asked Monday for the public's help in tracking down a man they say helped run one of the largest online child pornography websites ever investigated by law enforcement.

The suspect, whose real first name may be Shaun, but is known to law enforcement as John Doe, may live in southern New England within a 100-mile radius of the New Haven, according to U.S. Immigration and Customs Enforcement's Homeland Security Investigations.

"We know that because he has purchased gift cards in Norwalk and Wallingford, Connecticut, and mailed money from New York to co-conspirators," said Bruce Foucart, special agent in charge of the agency's New England office.

The suspect is between 40 and 50 years old, likely works in construction management and travels regularly, authorities said. He has degrees in electrical engineering and construction management and is proficient with computer programming.

He may have previously worked in IT or information security.

His expertise in IT may have helped him elude authorities, Foucart said.

"And he coached some co-conspirators on how not to be detected," he said.

He may also have a relative living in Hamburg, Germany.

Authorities do not have a photo of the man.

"We don't think there is imminent danger" to children," Foucart said, "and there is no specific knowledge that he was abusing children himself."

He is the only remaining suspected administrator of the website investigated as part of Operation Round Table, one of the largest online child exploitation investigations in history, which has already led to 14 arrests.

The public can report information anonymously through the toll-free tip line at (866) DHS-2-ICE.