SAN FRANCISCO (CBS SF) — San Francisco substitute teacher Marc Nunez has been charged in a federal criminal complaint with possession of child pornography, prosecutors announced Tuesday.

According to the complaint filed December 1 and unsealed Tuesday, Homeland Security agents served a federal search warrant at a residence in San Francisco on August 27, 2019 and seized among other things, a cell phone containing communications between the person whose residence was being searched and Nunez.

As the investigation proceeded, federal agents uncovered additional evidence that Nunez was a substitute teacher, after school helper, and kindergarten assistant at an unnamed private elementary school for boys in San Francisco.

In addition, federal investigators discovered Nunez corresponded with several individuals with whom he traded sexually explicit files of children.

The complaint further described cell phone messages and Skype messages in which Nunez received and discussed pornographic images of minors.

Prosecutors said Nunez believed that at least one of the persons with whom he was corresponding was a minor.

Nunez is charged with possession of child pornography and if convicted, he faces a maximum statutory sentence of 10 years in prison, 3 years’ supervised release, and a $250,000 fine.

Magistrate Judge Laurel Beeler ordered Nunez released on a $50,000 bail during his first court appearance on Monday. His next court appearance is scheduled for December 15 before Judge Beeler for a bond hearing.