ALEXANDRIA, Va.—A former high-level aide to Sen. Barbara Boxer has been sentenced to five years in prison on child pornography charges.

Jeff P. Rosato, 32, of Arlington, was sentenced Friday in a hearing before U.S. District Judge T.S. Ellis III. He received the minimum sentence allowed under federal guidelines and will have to register as a sex offender.

Rosato was fired from Boxer’s office in November after the California Democrat learned of the charges.

He 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.

Defense attorneys argued Rosato had been molested as a child.