Prosecutors charged Derks, 53, of Kenosha, with 20 felony counts of possessing child pornography. His attorney, Nancy Barasch, said she had just learned of the case Monday afternoon and knew little about Derks so far.
A criminal complaint said Derks allegedly told investigators the world has gotten "worse and worse" so he turned to children because they are beautiful. He denied ever having sexual contact with a child, and said no children had been to his apartment in the town of Kenosha and that he never tried to lure any there.
State Department of Justice agents learned about Derks through a tip from federal immigration officials investigating online child pornography. They said Derks purchased a 30-day membership to a site in 2006, according to court documents.
Derks fainted when state agents tried to interview him on Tuesday. He was taken to an area hospital.
Agents searched Derks' apartment the next day. The criminal complaint said every wall and flat surface, including cupboard doors and shelves, was covered with posters, photos and computer printouts of girls in various poses, states of undress or engaged in sex acts.
They found girls' underwear, multiple DVDs containing child pornography and girls on Kenosha-area beaches and two sets of partially clad adult- and adolescent-sized store mannequins. One of the mannequins was touching another's genital area.
The Olsen twins poster included a handwritten note stating the girls were 11. The note called Derks cute and invited him to participate in sex acts with them.
Lined along the living area walls were more than three dozen dolls. In the middle of the living area was a bed covered with stuffed animals. Dozens of images of children, including actress Dakota Fanning and kidnap victim Elizabeth Smart, were in a stack next to the bed.
Smart was 14 when she was abducted at knifepoint from the bedroom of her Salt Lake City home in October 2002. Her kidnappers raped daily during her nine months in captivity, and one of them took her as his wife in order to fulfill a religious prophecy.
None of the celebrity photos were pornographic, state agents said.
Police also discovered a Hannah Montana lamp with "Make Love to Me Mom" handwritten on the shade. They recovered 21 firearms and ammunition as well.
In the hospital, Derks allegedly told investigators he got child pornography off the Internet and had made all the DVDs they had found. He also said he used a telephoto lens to take hundreds of pictures of girls at Kenosha beaches, the complaint said.
He said he started writing on the pictures about four years ago and has fantasized about sex acts between mothers and daughters. He started buying the mannequins and dolls in 1988, saying they are beautiful.
He said he kept so many guns in case a "drunkard or crazy nut came though his door."