Two men from the Seattle area are among 72 people charged with viewing and trading child pornography as part of an international online network.

Attorney General Eric Holder and Homeland Security Secretary Janet Napolitano say a law enforcement effort called Operation Delego investigated more than 500 people around the world since the probe was launched in December 2009.

Holder and Napolitano say those charged were involved in Dreamboard _ a private, members-only, online bulletin board created to promote pedophilia.

According to documents released in the probe, members traded tens of thousands of graphic images and videos of adults molesting children 12 years old and under.

Among those identified from this area is William Barton, known to members as blackbart2010. He was arrested in April.

Agents traced an Internet provider address to Redmond and last week arrested 26-year-old Eric Francis. At his apartment, investigators seized 21 video files featuring sexually explicit images of children.

The U.S. Attorney says some of the victims were infants.

The Associated Press contributed to this report.