HOUSTON (AP) — A National Guard member arrested on a sexual assault charge while serving on the U.S.-Mexico border lost his job as a county jailer last year after being arrested for drunken driving and allegedly lying to investigators.

Luis Carlos Ontiveros, 30, was arrested Monday in Alpine, Texas, and accused of sexually assaulting a woman at a motel. He was part of the National Guard mission that began in April at the call of President Donald Trump, who has since sent active-duty soldiers to the border as well.

Records obtained by The Associated Press on Thursday show Ontiveros was fired in January 2017 by the El Paso County Sheriff's Office. Sheriff Richard Wiles fired him one month after he was arrested for driving while intoxicated, accusing him of crashing his car while drunk and lying about it to police and investigators.

But Ontiveros remained in the Guard, where he's currently a sergeant.

Ontiveros didn't respond to phone messages left Wednesday or Thursday at a number listed for him. The Guard said it is cooperating with investigators.

"We will not tolerate acts such as sexual assault, sexual harassment, and any forms of social media that degrade or demoralize unit cohesion and readiness," the Guard said in a statement. "We must ensure all victims receive our utmost support and care."

According to court records in El Paso, Ontiveros was charged with a misdemeanor DWI while having a blood-alcohol level of over 0.15 percent. He completed a pretrial diversion program and the case was dismissed.

Ontiveros, who had joined the sheriff's office in 2011, appealed his dismissal, but an arbitrator sided with the sheriff. He enlisted in the Guard in 2007.

The Texas Military Department, the umbrella agency for the state's Guard divisions, would not say whether it was aware of Ontiveros' DWI or firing from the sheriff's office, or whether it took any action regarding Ontiveros' status in the Guard. The El Paso County Sheriff's Office, which released records of Ontiveros' termination, wouldn't say whether it notified the Texas National Guard about his firing.

Geoffrey Corn, a military law expert and professor at the South Texas College of Law, said in an email that the military's most common response to a first-time DWI charge would be a letter of reprimand. A reprimand "will often trigger a process to fire the soldier," Corn said.

Ontiveros is the second guardsman in Texas known to have been arrested since the Guard was sent to the border.

Edwin Baez, 20, was charged in August with stealing 1.5 kilograms of methamphetamine. Baez was detailed to an international bridge in Laredo. He has pleaded not guilty.

Ontiveros was released on $20,000 bond in the sexual assault case.