Updated: 10:09 p.m.

A senior staffer for Sen. Barbara Boxer (D-Calif.) was charged with distributing and receiving child pornography last week, prompting Boxer to immediately fire him.

Jeff Rosato had worked in Boxer’s office since 2005, most recently as the senior policy adviser and counsel on the Environment and Public Works Committee.

He was arrested after the FBI investigated another suspect who had exchanged illicit material with Rosato online and who sent more than 600 images and movies of child pornography to an undercover FBI agent he believed to be a 13-year-old boy, according to an FBI affidavit.

The online chats occurred from Jan. 2 to Jan. 23 over Google Hello, a photo-sharing program that was shut down in June. To identify Rosato, the FBI subpoenaed Google and Comcast.

In a Nov. 7 search of Rosato’s Alexandria home, FBI agents found a computer with “approximately 200 images of child pornography and child erotica, and several movies containing child pornography and child erotica.” Many of the images showed prepubescent boys engaged in sexual acts, according to the affidavit.

Natalie Ravitz, Boxer’s spokeswoman, said in an e-mail that the office took immediate action.

“On Friday, the Justice Department informed our office of criminal charges made against a Senate employee,” she said. “Senator Boxer has zero tolerance for crimes against children, and the employee was immediately terminated. Our office is cooperating fully with the Department of Justice in this matter.”

A call to Patrick Anderson, Rosato’s attorney, was not immediately returned.

Rosato was released under the condition that he stay away from children and computers, according to court documents.