Nunez, who worked for the Bexar County Sheriff's Office for 10 years, silenced the mother of the child by threatening to reveal her undocumented status and deport her back to Guatemala if she reported the assault.
The child "made an outcry to her mum" who brought her to a local fire station to report the abuse Saturday evening, according to the Washington Post.
He was arrested Sunday around 3am and is being held without bail.
"The details of the case are, quite frankly, heartbreaking, disturbing, disgusting and infuriating all at the same time," Salazar said in a press conference.
"Folks like this are creatures of habit and opportunity. I don't know that he was purposely targeting the undocumented community.
"Certainly I think what appealed to him, in this case anyway, is the vulnerability of that community because of the fact that they're less apt to report things."
Police have not released the victim's residency status and the mother has been given a protected status in the case. Their identities have not been released.
Nunez is due in court Monday afternoon. If found guilty, he could face a minimum of 25 years behind bars. Nunez's charge of super aggravated sexual assault of a child means that the alleged victim is under the age of 6, which allows for a harsher sentence structure in Texas.
Nunez has been placed on administrative leave pending the investigation.
Given the nature of the crime, Sheriff Salazar urges undocumented immigrant victims to speak up regardless of their status.
- With AP
