A high-level aide to California Democratic Sen. Barbara Boxer has been charged in federal court with receiving and distributing child pornography.

The aide, Jeff Rosato, 32, was arrested last Friday. Boxer's office fired him that same day upon learning of the charges.

Rosato appeared in federal court in suburban northern Virginia on Wednesday and was released to home detention on condition he not interact with children or use a computer. He was not required to post bail or bond money but is being told to undergo medical treatment.

"On Friday, the Justice Department informed our office of criminal charges made against a Senate employee. Sen. Boxer has zero tolerance for crimes against children, and the employee was immediately terminated," Boxer spokeswoman Natalie Ravitz said in a statement Thursday. "Our office is cooperating fully with the Department of Justice in this matter."

Rosato had worked for Boxer since early 2005, beginning in her personal office as a legislative assistant and last year becoming a counsel to the Environment and Public Works Committee, which Boxer chairs. His areas of expertise included water policy, oceans and endangered species.

Rosato's attorney, Patrick N. Anderson of Alexandria, Va., did not immediately return a call seeking comment.

According to an affidavit by FBI special agent Chad Gallagher supporting the criminal complaint and arrest warrant, Rosato was tracked through a now-defunct Google program called Google Hello. He allegedly exchanged hundreds of pornographic images with another user who'd been sharing child porn images and movies with an undercover detective posing as a 13-year-old boy.

Investigators subpoenaed Google Inc. and Comcast in order to identify Rosato and last week executed a search warrant on his Arlington, Va., home, seizing computers and hard drives.

A preliminary review of Rosato's personal laptop computer, which was in his bedroom, found some 200 child porn images and some videos, according to the affidavit. "Many of the images and videos depict prepubescent boys engaged in sexual acts," the affidavit stated.

The criminal complaint charged Rosato with one count of receipt of child pornography and one count of distribution of child pornography, both felonies.

The charges were first reported Thursday by The (Washington) Examiner newspaper.