She was being held at the Metropolitan Detention Center in Downtown Los Angeles, police said, as they wait for Texas authorities to take her home.
Texas' Tarrant County District Attorney has formally charged her with Hindering Apprehension of a Felon and set bail at $1 million. It is still unclear when she will be transported from California to Texas.
Tonya Couch, 48, was escorted overnight by officials from Los Angeles International Airport, Terminal 2, to an unmarked Sedan.
Couch, who was wearing handcuffs, did not say anything.
He has been granted a three-day stay in his deportation case, which will now go before a judge who could potentially take longer to make a decision, according to a government official. It was unclear how long that would take.
A Mexican immigration official said Wednesday night Couch was being transferred to Mexico City from Guadalajara to follow up on the injunction.
Ethan, 18, and his mother were arrested in Puerto Vallarta, Mexico, Monday after U.S. Marshals and other American law enforcement agencies had been searching for them for nearly two weeks.
"We believe that, until the Mexican Federal Judge enters an appropriate order authorizing it, Ethan will not be returned to the United States," they said. "We are uncertain how long the legal process in Mexico will take or how it will ultimately be resolved."
The teen was being sought after missing a mandated probation check-in with Texas authorities earlier this month. During his 2013 trial on drunken-driving charges, a defense witness testified that Ethan was afflicted with so-called "affluenza,” meaning his irresponsible behavior and lifestyle were a product of his affluent upbringing and "profoundly dysfunctional" parents.
Editor’s Note: An earlier version of this story incorrectly stated that Tonya Couch was arrested by the Los Angeles County Sheriff’s Department. She was actually arrested by the Los Angeles Police Department.