GUADALAJARA, Mexico (AP) — A teen fugitive from Texas known for using an "affluenza" defense and his mother were scheduled to depart for the U.S. after authorities said a phone call for pizza led to their capture in the Mexican resort city of Puerto Vallarta.

Eighteen-year-old Ethan Couch and his mother, Tonya Couch, were being held at immigration offices in Guadalajara to be returned to the United States aboard a commercial flight to Houston on Wednesday, authorities said.

A U.S. Marshals Service agent tipped local authorities off Monday to the location of Couch — who was on juvenile probation after killing four people in a 2013 drunken-driving wreck — and his mother, according to a police report issued by the Jalisco state prosecutors' office. Couch disappeared as authorities investigated whether he had violated the terms of his probation.

During the sentencing phase of Couch's trial, a defense expert argued that his wealthy parents 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.

According to the police report, one of the Couches' telephones had been used to order delivery from Domino's Pizza to a condominium complex in Puerto Vallarta's old town, far from the glitzy resorts of the city's newer section.

Agents from the prosecutors' office went to the complex, where a tourism operator told them that the people who had occupied the condo were asked to vacate because the owners were coming to stay, the report said. The Couches then moved to an apartment, and the agents set up a surveillance operation in the surrounding streets.

On Monday evening, two people matching the Couches' description were spotted and intercepted. The police report said they behaved evasively, claimed to be carrying no IDs, gave inconsistent stories about their names and failed to provide proof of their legal migratory status in Mexico.

They were taken into custody and handed over to immigration officials.

Tarrant County Sheriff Dee Anderson said Tuesday that the Couches had prepared to be gone a while, even dyeing Couch's blond hair black.

"They had planned to disappear. They even had something that was almost akin to a going-away party before leaving town," Anderson said. He would not give details about the event, including how many people attended.

Anderson said Couch and his mother apparently crossed the border in her pickup and drove to Puerto Vallarta. It was not clear whether they had any accomplices.

No immediate charges were planned for others who may have known about or assisted with the flight plan, Anderson said. He said authorities have no evidence that Couch's father, who owns a sheet metal factory in North Texas, was involved.

The sheriff has said he believes the two fled in late November after a video surfaced that appears to show Couch at a party where people were drinking. Authorities had begun searching for the pair after Ethan Couch missed a mandatory appointment with his probation officer on Dec. 10.

If found to be drinking, Couch's probation could be revoked and he could face up to four months in jail. Once returned to Texas, Couch will be held in a Tarrant County facility until a probation violation hearing Jan. 19.

Tarrant County District Attorney Sharen Wilson said that at the hearing she plans to ask a judge to transfer Ethan Couch's case to adult court. Couch would then face up to 120 days in an adult jail, followed by 10-year probation. If he violates probation, he could face up to 10 years in prison per death, Wilson said.

If the judge declines to transfer Couch to adult court, Wilson will ask that his probation be revoked, in which case he could be held in a juvenile facility until his sentence expires when he turns 19 next April.

Anderson said an arrest warrant was being issued for Tonya Couch on charges of hindering an apprehension, a third-degree felony that carries a sentence of two to 10 years in prison.

Ricardo Ariel Vera, the representative of Mexico's immigration institute in Jalisco state, said the mother and son were being held at immigration offices in Guadalajara and would be returned to the United States aboard a commercial flight to Houston.

"They are going to be sent back to their country, given that they were in Mexico improperly," Ariel Vera said. "They would have had to enter, for example, as tourists, but they entered without registering."

He initially said that would happen Tuesday; however, another immigration official who is not allowed to be quoted by name told The Associated Press that there were no seats available on commercial flights and the return would be Wednesday.

Couch's attorneys, Scott Brown and Reagan Wynn, said they won't comment until they speak with him, which likely won't happen before Couch reaches the U.S.

Couch was driving drunk and speeding on a road south of Fort Worth in June 2013 when he crashed into a disabled SUV off to the side, killing four people and injuring several others, including passengers in his pickup truck.

He pleaded guilty to four counts of intoxication manslaughter and two counts of intoxication assault causing serious bodily injury. A judge sentenced him in juvenile court to 10 years' probation and a stint in a rehabilitation center.

Greg Coontz, a Burleson, Texas, attorney representing the family of one of the victims of the crash, says his clients look forward to seeing the Couches face the consequences of their actions.

"I can't think of a worse attempt to evade punishment," he said.

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Schmall reported from Fort Worth, Texas. Associated Press reporters E. Eduardo Castillo, Peter Orsi and Mark Stevenson in Mexico City contributed to this report.