The investigation began in March 2007 when Anderson was arrested for allegedly having sex with an underage girl. That led to the discovery of a video allegedly showing Anderson having sex with an 8-year-old girl ten years earlier.
While in custody in relation to that investigation, authorities say they discovered more than 11,700 images of suspected child pornography on one computer, and more than 8,250 additional images and 450 child pornography videos on CDs and DVDs.
"Subsequent analysis of other computers and related equipment allegedly revealed more than 13,000 additional images and 70 more videos containing suspected child pornography," a release from the U.S. Attorney's Office says.
Anderson is charged with possession and manufacture of child porn and faces up to 40 years in prison if convicted.