FORT WORTH, Texas/PUERTO VALLARTA, Mexico (Reuters) - A rich Texas teenager who fled with his mother to Mexico to avoid possible jail time for violating his probation in a drunken-driving crash that left four people dead planned the flight and even held a farewell party, U.S. authorities said on Tuesday.

Ethan Couch, 18, became known as the “affluenza” teen during his trial in juvenile court over the 2013 crash. He and his mother were captured by Mexican authorities on Monday in the Pacific Coast beach city of Puerto Vallarta. They were likely to be returned to the United States on Wednesday.

During Couch’s trial, a psychologist sparked outrage by saying in his defense that Couch was so wealthy and spoiled he could not tell the difference between right and wrong. He was sentenced to 10 years drug-and-alcohol-free probation for intoxication manslaughter, a punishment condemned by critics as privilege rewarded with leniency.

Couch and his mother, Tonya Couch, fled the country after a video surfaced online apparently showing Couch at a party where beer was being consumed. Authorities had been investigating that video as a potential parole violation.

Couch had missed a mandatory meeting with his probation officer, prompting officials in Tarrant County, Texas, to issue a warrant for his arrest earlier this month.

Couch and his 48-year-old mother were tracked down and captured near Puerto Vallarta’s seafront promenade. Mexican authorities said they had been working with the U.S. Marshals Service since Dec. 24 to locate the pair.

The mother and son apparently entered Mexico by land, said Ricardo Vera, a local official for Mexico’s National Migration Institute. He said the two did not register when entering Mexico and it was not clear where they came in. Vera said owing to a shortage of seats on Tuesday flights to Houston, the two were now more likely to return to Texas on Wednesday from Jalisco’s state capital, Guadalajara.

“They had planned to disappear,” Tarrant County Sheriff Dee Anderson told a news conference in Fort Worth, Texas. “They even had something that was almost akin to a going-away party before they left town.”

When they arrived back in the United States, Couch would appear in juvenile court and his mother would be arrested for hindering an apprehension, Anderson said.

Ethan Couch’s attorney, Reagan Wynn, declined to comment, saying in a statement he had not had the chance yet to speak with his client.

In Puerto Vallarta, eyewitness Cristina Barraza said she saw Tonya Couch’s arrest. She was led with hands behind her head by a man in plainclothes to a white pickup truck in front of a modest four-story building where the pair were reportedly staying.

Afterwards, the vehicle sped off, said Barraza, saying she did not see Ethan Couch during the arrest.

She also recalled an exchange with the mother last week as she sat outside her home on the sidewalk across the street. “She came along here and greeted me in Spanish. She was nice.”

U.S. national Ethan Couch is pictured in this undated handout photograph made available to Reuters on December 29, 2015 by the Jalisco state prosecutor office. REUTERS/Fiscalia General del Estado de Jalisco/Handout via Reuters

Jalisco’s Attorney General Eduardo Almaguer told reporters the pair had first stayed in a bungalow close to the beach, then moved to a “more discreet” apartment further into town. They were detained while arriving back at the apartment on Monday evening and put up no resistance, he said.

BLOND TO DARK-HAIRED

A police booking picture from Mexico showed the previously blond Ethan Couch with dark hair, which the sheriff said suggested Couch was trying to change his appearance.

Tarrant County District Attorney Sharen Wilson said that she expected the judge to hold Couch after his juvenile hearing, and that she hoped it would be in an adult jail.

At a previously scheduled Jan. 19 court hearing, Wilson had planned to ask a judge to transfer Couch’s case into the adult court system from the juvenile system, putting Couch under stricter supervision and leaving him open to harsher punishment if he violated probation.

If he were in the adult system, Couch could face 120 days in jail for not meeting with his probation officer as required, and he could face up to 40 years in prison if he violated probation again after that, Wilson said.

U.S. Marshal Rick Taylor and Anderson declined to say how authorities tracked Couch down, but CNN said the marshals used Couch’s mobile phone to locate him.

‘HANDS-OFF’ PARENTING

In the fatal accident, Couch, then 16, was speeding and had a blood-alcohol level of nearly three times the legal limit when he lost control of his pickup truck and fatally struck a stranded motorist on the side of the road and three people who had stopped to help.

Susan Cloud, a friend of Brian Jennings, one of those killed, said she felt conflicted about what should happen to Couch, but wished he had not thrown away his second chance under his probation.

“I feel more negatively toward his mother than I do him,” Cloud said. “The parents seem to have a completely hands-off approach.”

Sheriff Anderson said last week that the passports for Couch and his mother had been reported missing by the teen’s father, who has cooperated with investigators. Fred Couch is divorced from the mother and owns a successful sheet metal business near Fort Worth.

The “affluenza” term was apparently used for the first time explicitly in defense during Couch’s trial, but has been a theory in sociological and psychological circles since the late 1990s to explain the impact of indulgent parenting, said Daniel Medwed, a criminal law professor at Northeastern University in Boston.

The notion of rich kids getting leniency based on their advantages sparked a public backlash against the theory, Medwed said, adding, “My hunch is this latest parole incident will mark the end of its use.”