CHICAGO - A janitor at an elite state academy for teenagers talented in math and science was charged Thursday with possession of child pornography, and the school said FBI agents were checking to see if some of the material had gotten into its computer system.

Robert Reese, 37, of Ottawa appeared briefly before U.S. Magistrate Judge Jeffrey Cole early Thursday after agents arrested him Wednesday at the Illinois Mathematics and Science Academy.

Cole ordered Reese held pending a bond hearing later. A message left at the Evanston office of Reese's attorney, John T. Kennedy, was not immediately returned.

The Aurora-based academy is a special state school for students in grades 10 through 12 who have extraordinary talent in math and science.

An FBI document filed with the court along with a criminal complaint against Reese said that he not only admitted to collecting pornographic images of girls as young as three but admitted he had molested one girl.

Academy spokeswoman Brenda Buschbacher said Reese had been put on administrative leave with pay pending the outcome of the investigation.

"He had minimal contact with students," she said.

The school requires all of its employees to submit to a criminal background check, and Buschbacher said Reese, hired in 1994, had passed.

The school issued a statement Thursday afternoon saying that the FBI was "conducting a criminal investigation of an IMSA employee for alleged inappropriate use of IMSA's computer network from a home computer."

FBI spokesman Ross Rice declined to comment on the school's statement that agents were trying to determine if pornographic material had gotten into the academy's computer system. He did say there was no evidence that anyone else at the school was involved.

An FBI affidavit said agents had searched Reese's home and discovered a Lexar Jump Drive, commonly known as a "thumb drive" or "memory stick," in the bedroom. It said more than 200 images of girls as young as three, some in sexual acts with adults, were discovered.

When agents went to the academy Wednesday to question Reese, he readily admitted to buying the child pornography, the affidavit said. It said he also admitted molesting a girl "who at the time of molestation was between the ages of three and five years old."

If convicted of the only charge placed against him so far, possession of child pornography, Reese could be sentenced to a maximum of 10 years.