A special education teacher’s assistant and care provider in Riverside County, California, was charged with involvement in a child pornography ring that spanned three counties in Southern California, authorities said Tuesday.

John David Yoder, who formerly worked at Desert Hot Springs High School, has been charged with oral copulation on a child under 14, trafficking of a child under 18, conspiracy, lewd acts on a child under 14, and aiding arrest avoidance in another, local news station KTLA reported.

Yoder was arrested on Jan. 30, within days of his two accomplices being apprehended by a task force dedicated to fighting sex crimes against children, Riverside County prosecutors reportedly said.

Yoder was found after a man named William Clyde Thompson was arrested while approaching the children. Thompson, a Las Vegas resident, was arrested in Needles, California, on Jan. 27. Authorities say his cellphone records implicated Yoder, and a third man, Erick Alan Monsivais.

Officials said the suspects were approaching children at parks in Desert Hot Springs and posing as members of a modeling agency. Authorities described him as being part of a “significant ring of human traffickers and child pornographers.”

Robert Goesch, a special agent from the Department of Homeland Security, told the Los Angeles Times that investigators are trying to identify others believed to be involved in the alleged operation.

“In the many years I've personally been involved with these types of investigations, this has to be very near the top as far as egregious violators," Goesch told the LA Times Thursday. "Often, we see one guy doing stuff on his own, trading or working with anonymous people around the world. Here you have ... people who knew each other and worked with each other, collaborated to exploit and hurt these children."

While Monsivais and Yoder have pleaded not guilty, Thompson is yet to be arraigned.