Rio Grande City, TX (KRGV) — A Rio Grande City High School teacher was arrested after “flirty” text messages between him and a student were shown to a teacher, according to a criminal complaint obtained by Channel 5 News.

The teacher, identified as Francisco Contreras Jr., admitted to investigators that he had sex with the student "on more than 10 occasions," and one of those times was at the school, the complaint said.

Contreras was booked at the Starr County jail on Oct. 7 on charges of improper relationship between an educator and a student and two counts of sexual assault of a child. A spokesperson for the Starr County Sheriff's Office said bond for Contreras was set at $150,000.

County jail logs do not currently list him as an inmate.

According to the complaint, a student told a teacher that Contreras was in a romantic sexual relationship with another student. The student showed the teacher photos of the student and Contreras kissing, as well as photos of "flirty" text messages between the two.

Investigators with the sheriff's office questioned Contreras, who confessed to the relationship the complaint said.

According to the complaint, Contreras met the student in February, and the improper relationship happened between April 2026 and October 2026.

In a statement issued on the day Contreras was arrested, Rio Grande City ISD said they had suspended an educator. 

As of Thursday afternoon, Contreras was listed on the Rio Grande City High School website as a special services teacher.