DALLAS -- High-profile Mexican attorney Fernando Benitez will represent "affluenza" teen Ethan Couch in his fight to stay in Mexico, CBS affiliate KTVT reported.

Benitez has been called a "rock star" and is the same attorney who got a U.S. Marine out of a Mexican prison last year where he had been held for seven months.

Couch, 18, won a delay in his deportation based on a constitutional appeal in Mexico that could lead to a trial process that could last weeks or even months.

He is being held in a detention center in Mexico City until a judge hears arguments on whether he was rightfully detained.

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Couch's mother, Tonya Couch, 48, was returned to the United States early Thursday after her deportation from Mexico. She has been charged in Tarrant County with hindering an apprehension, a felony charge that carries a two- to 10-year prison sentence, and is being held on a $1 million bond.

Any flaw in the process of his detention by Mexican immigration authorities can be considered a violation of due process and of his human rights, San Antonio attorney Javier Lopez de Obeso, who is licensed to practice in Mexico, said Thursday.

"If the immigration authorities didn't act properly, he can find a way to stay in Mexico for more time," said Lopez.

U.S. authorities expressed a similar sentiment earlier this week.

"The Couches have legal counsel, and it seems to me that if they wanted to they could pay them as much money as they want to to drag this thing out as long as they want to," Richard Hunter, chief deputy for the U.S. Marshals Service in South Texas, said Wednesday.

If the judge considering the appeal decides there was a mistake made in the process of detaining Couch, he could be released, and authorities would have to re-arrest him, Lopez said.

Treaties between the U.S. and Mexico say that Mexican authorities have to respect Couch's warrant in the U.S., so unless he files for asylum, he will not be able to stay in Mexico indefinitely, said Aldo Salazar, a Texas attorney also licensed to practice in Mexico.

"Asylum is granted to those who can prove a well-founded fear of persecution. I'm not sure 'affluenza' would qualify," said immigration attorney Nicolas Chavez.

Tarrant County Sheriff Dee Anderson has said he believes Couch and his mother fled to Mexico in late November after a video surfaced that appears to show Couch at a party where people were drinking, which would be a violation of his probation. The mother and son were arrested Monday after using a phone to order pizza delivery that was traced to a condominium complex in the Mexican resort city of Puerto Vallarta.

Couch, who was 16 at the time of the crash and was tried in juvenile court, received 10 years' probation for driving drunk and crashing into a disabled SUV parked on the side of the road in 2013. The collision killed four people and injured several others, including passengers in his truck. He pleaded guilty to four counts of intoxication manslaughter and two counts of intoxication assault causing serious bodily injury.

During the sentencing phase of his trial, a defense expert argued that Couch's wealthy parents had coddled him into a sense of irresponsibility - a condition the expert termed "affluenza." The condition is not recognized as a medical diagnosis by the American Psychiatric Association, and its invocation drew ridicule.

Judge Jean Boyd sentenced Couch to probation over the objections of prosecutors who asked for 20 years' detention. Couch's attorneys argued probation would be more effective than detention because Couch could have been eligible for release in as few as two years.

Benitz told KTVT he has not spoken with Couch yet but hopes to on Tuesday.

He also said no gun was found during Couch's detention and calls that information "gossip from unconfirmed sources."

Benitez would not say who hired him.