GRAND FORKS (AP) - A man charged in one of the area's largest child pornography cases has indicated in court documents that he will plead guilty.

Steven Cartier, of Oberon, was arrested last spring after Spanish authorities alerted the FBI of American computer addresses detected during an international child pornography investigation.

In documents filed this week in federal court, Grand Forks attorney David Dusek said Cartier decided to change his plea after U.S. District Judge Rodney Webb denied motions to throw out evidence gathered by the FBI. Cartier had pleaded not guilty in November.

He is charged with production, receiving and possession of child pornography and lying to FBI agents. Authorities say he also faces a gross sexual imposition charge in Ramsey County in an assault on a girl shown in a video.

Dusek told court officials he would be out of town for two weeks and Webb will be gone for much of March, so the plea change probably will not happen formally until late March or early April.

Assistant U.S. Attorney Jennifer Puhl said Cartier had "hundreds of thousands, if not a million, images of child pornography." Evidence collected from his home included computers and dozens of CDs and videos, with images involving more than 1,000 child victims, she said.

"It's the biggest we've seen," Puhl said.

She said the amount of child pornography discovered in Cartier's possession could increase his prison sentence. The mandatory minimum sentence for the production of child pornography is 15 years and the mandatory minimum for receiving it is five years, she said.

Cartier traded child porn images via the Internet with others through networking with "peer groups," and other Internet linkups, Puhl said.