(WASHINGTON)-- Catholic priests, a police officer, a nurse, a teacher's aide and a school bus driver were among those charged in a 14-month nationwide crackdown known as "Operation Candyman" that targeted child pornography on the Internet, the FBI said on Monday.

FBI officials said about 90 people in more than 20 states have been charged in an undercover investigation of three electronic message groups maintained by Yahoo! Inc that involved the posting, exchanging and transmitting of child pornography via e-mail, bulletin boards and file transfers.

One official said about 40 people are in custody while 50 are expected to be in custody by the end of the week as part of the first phase of the crackdown on "an international ring of pedophiles and predators devoted to trading and propagating pornographic images of children over the Internet."

Of the three or four clergy members who have been charged, two were Catholic priests, including one in Baltimore, the officials said. The Catholic Church has recently been hit with a number of scandals in which priests have sexually molested young boys.

They said one group, www.egroups.com/groups/thecandyman, had an estimated 7,000 members, with 2,400 of them overseas. Such groups create cyberspace communities of like-minded individuals who seek to communicate privately on a single subject matter using e-mail and dedicated Web sites.

The Candyman Web site has been shut down, the officials said.

"There will be no free riders on the Internet for the traffickers in child pornography," Attorney General John Ashcroft (news - web sites) told a news conference at FBI headquarters.

The officials said a number of those caught up in the investigation involved positions of trust, including a guidance counselor, a foster care parent and professionals in the medical and military fields.

A respiration therapist in Little Rock committed suicide, they said.

FBI Executive Assistant Director Bruce Gebhardt said Yahoo cooperated with the FBI's investigation. He said all three message groups have been shut down.

The FBI has conducted more than 230 searches as part of the investigation, which began after an undercover FBI agent in Houston discovered the three groups, the officials said.

"This group is for People who love kids. You can post any type of messages you like too or any type of pics and vids you like too," the FBI quoted one of the group's Web sites as saying.

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