DALLAS (AP) — Authorities said a Texas teenager serving probation for killing four people in a drunken-driving wreck after invoking an "affluenza" defense was in custody in Mexico, weeks after he and his mother disappeared.

The public affairs department of the prosecutors' office in Mexico's Jalisco state confirmed that 18-year-old Ethan Couch and his mother, Tonya Couch, were detained in Puerto Vallarta around 6:00 p.m. Monday. No further details were immediately available.

The Tarrant County District Attorney's office also told local media outlets that the two had been taken into custody in the Pacific resort city. A spokeswoman for the office could not immediately be reached by The Associated Press for further comment.

Authorities began searching for the pair after Ethan Couch failed to keep a mandatory appointment with his probation officer on Dec. 10, leading authorities to issue the juvenile equivalent of an arrest warrant for him.

Tarrant County Sheriff Dee Anderson 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. If found to be drinking, Couch's probation could be revoked and he could be sentenced to up to 10 years in prison.

A spokesman for the Tarrant County Sheriff's Department has declined to say whether Tonya Couch is facing any charges.

There was no immediate comment Monday night from the U.S. Marshals Service, which had issued a wanted poster promising a reward of up to $5,000 for information leading to Couch's whereabouts and capture.

In June 2013 at age 16, Ethan Couch was driving drunk and speeding on a dark two-lane road south of Fort Worth when he crashed into a disabled SUV off to the side, killing four people and injuring several others, including passengers in Couch's pickup truck.

Couch pleaded guilty to four counts of intoxication manslaughter and two counts of intoxication assault causing serious bodily injury. Because of his age, he wasn't certified as an adult for trial and a judge sentenced him in juvenile court to 10 years' probation and a stint in a rehabilitation center.

During the sentencing phase of his trial, Couch's attorneys relied on a defense expert who argued that Couch's 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 widespread ridicule.

Anderson, the sheriff, was among those critical of the judge's decision not to incarcerate Couch. The sheriff said that the teen has never expressed remorse for his actions and that his case sparked more outrage than any other Anderson has encountered in his law enforcement career.

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Associated Press writer Peter Orsi in Mexico City contributed to this report.