A Texas sheriff's deputy accused of repeatedly sexually assaulting a 4-year-old girl threatened the victim's mother into staying quiet about the assaults, authorities said Sunday.

Jose Nunez, a 10-year veteran of the Bexar County Sheriff's Department, was off-duty when he was arrested early Sunday. The 47-year-old faces a felony charge of aggravated sexual assault of a child, Sheriff Javier Salazar said at a news conference.

Jose Nunez (Bexar County Sheriff's Office)

Salazar said investigators suspect that the girl had been assaulted multiple times over the course of several months.

The girl's mother is an undocumented immigrant, Salazar said, and Nunez told her she'd be deported if she told authorities about the assaults.

"The details of the case are quite frankly heartbreaking, disturbing, disgusting and infuriating all at the same time," the sheriff said.

The girl "made an outcry" to her mother sometime overnight Sunday, Salazar said. The girl's mother took her to the fire department to make a report.

"The little girl now is safe, and we're continuing to process the case," he said.

Salazar said the sheriff's office was completing paperwork to give the mother a type of protected status during the criminal investigation that would prevent her from being deported.

Officials believe there could be more victims, the sheriff said. Anyone with information about the case may contact the Bexar County Sheriff's Office at 210-335-6070.

The department is also conducting an internal investigation.