SOUTHBRIDGE (CBS/AP) — A Southbridge teacher charged with sending nude photos of himself to a high school student remains free on bail after pleading not guilty.

Joseph Zuniga of Webster pleaded not guilty Thursday to a charge of dissemination of obscene matter to a minor.

READ MORE: 'A Step In The Right Direction': Juneteenth A Symbol Of Hope For Many In Boston

Police say the 23-year-old Southbridge Middle/High School teacher sent nude photos to the 17-year-old boy through a Facebook message. A school resource officer overheard students talking about it and alerted police.

“In some of them we could clearly see his face attached to the image, so we knew it was the teacher,” the officer said.

The school district says Zuniga is no longer an employee. He taught English to non-native speakers.

READ MORE: Video Shows Bear Entering Truck In Thornton, NH

He is free on $500 bail with conditions, including no unsupervised contact with children under 16, except his siblings.

Zuniga has legal custody of his younger brother and sister.

Zuniga and his lawyer did not respond to questions from the media.

MORE NEWS: Parent, 2 Children Rescued From Salisbury Beach Rip Current

(TM and © Copyright 2015 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2015 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)