(CNN) Will Ethan Couch, the "affluenza" teen, get off lightly again?

Couch drew the ire of many after a judge sentenced the then 16-year-old to 10 years of probation for a 2013 drunk driving crash that killed four people.

Those who felt the sentence too lenient felt validated when Couch violated his probation and fled. He was detained Monday in Mexico.

But if you are expecting a judge to throw the book at him, be warned that the book might not be too heavy.

As of now, the most severe punishment Couch could face is 120 days in adult jail, Tarrant County District Attorney Sharen Wilson said at a press conference Tuesday.

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The district attorney explained the dilemma she faces:

• Ethan Couch was sentenced as a juvenile and violated his probation as ordered by the juvenile court system.

• Under Texas law, Couch, now 18, would be punished for his violation in the juvenile system.

• The maximum sentence that a juvenile judge can dish out for a violation of his juvenile probation is imprisonment in a juvenile facility until Couch turns 19, which is April 11, 2016.

• The DA wants to transfer Couch's sentence to adult court. But since this violation happened in the juvenile system, Couch effectively would start with a clean slate in the adult probation system. That is, the adult court judge could not punish Couch for violations he committed as a juvenile.

• At the time a judge reassesses Couch's probation in the adult system, he has the power to put Couch in adult jail for a maximum of 120 days.

The 120 days in jail won't please those who think Couch deserves worse, but as the facts stand now, it is what the law allows.

If Couch ends up on adult probation and violates it as an adult, he could face up to 40 years in jail, Wilson said. Couch also could find himself behind bars for longer if he is found to have committed any new crimes and is charged and convicted as an adult for those crimes.

Couch and his mother, who were being sought by Texas authorities, have been detained in the Pacific resort town town of Puerto Vallarta, Mexico.

Ethan Couch's mother, Tonya Couch, has been charged with hindering the apprehension of a juvenile, and if convicted, faces between two and 10 years in jail, Wilson said.

It's tough to explain the legal maze that stands to benefit Ethan Couch in the form of a light punishment for violating his probation.

The judge who hears the case "will throw the book at him, but the book is only a few more months because he turns 19," said Larry Seidlin, a former state court and juvenile court judge in Florida. "So the legal issue is: Can the prosecutor move this case to adult court and try to get adult sanctions, get some state prison time. It's a close question because double jeopardy is going to take effect. We've already gone through his case. We've already done a plea bargain."

Tracking the teen

A warrant was issued in mid-December for Couch to be taken into custody after his probation officer couldn't reach him. He appears to have dropped off the radar after a video emerged that allegedly showed him at a party where alcohol was being consumed, according to authorities.

Couch had been ordered to stay away from drugs and alcohol for the duration of his probation.

When Couch was captured in Mexico with dark hair and dark goatee, Texas authorities say the 18-year-old had the look of someone on the run, trying to change his appearance.

"I don't think you go on a vacation and disappear, and don't tell anybody, and cut your hair and dye your hair, and hide out in a shabby apartment in a resort town. ... They fought so hard to keep him out of trouble when he killed four innocent people drinking three times the legal limit of alcohol, there's no doubt in my mind that when the video came out that showed him at that party and he was facing a possible revocation of probation, they made a conscious decision to run, and they did," Tarrant County Sheriff Dee Anderson told CNN's AC360 on Tuesday.

Before they left for Mexico, they "even had something that was almost akin to a going away party," Anderson told reporters.

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Weeks later, Couch's cell phone use might have led authorities to the pair.

The U.S. Marshals Service tracked Couch down using electronic surveillance, including tracking a cell phone believed to be linked to him, an official briefed on the investigation told CNN.

The Marshals Service alerted Mexican authorities, who detained Couch and his mother, the official said.

They tracked down the pair inside an apartment building, Jalisco state Attorney General Eduardo Almaguer Ramirez told reporters Tuesday.

Authorities' initial search for Couch focused on the beach area, he said, but eventually their investigation pointed them to the apartment building, which is in a more discreet location near the center of town. The pair had entered Mexico as tourists and had exceeded their allowed length of stay, Ramirez said.

Couch is wanted by authorities in Tarrant County for allegedly violating his probation. His mother, Tonya, was listed by Texas authorities as a missing person after her son's disappearance, and the authorities said they believed she was assisting him.

What comes next

Couch and his mother were turned over to Mexico's immigration authorities because police couldn't determine whether they were in the country legally, according to a statement from the Jalisco state prosecutor's office.

Ethan Couch was detained in Mexico.

The prosecutor's office said the pair will be deported to the United States.

U.S. authorities expect them to return to the United States on Wednesday, according to an official briefed on the matter.

As of Tuesday, mother and son remained in custody in Puerto Vallarta, said Ricardo Vera, the representative in Jalisco for Mexico's National Institute of Immigration.

Ethan and Tonya Couch met with U.S. consular officials and underwent a routine medical checkup, Vera said.

They were also allowed to speak with family in the United States, he said.

The Couches told immigration officials that they entered Mexico through the crossing in Tijuana. They did not have the proper paperwork to be visiting Puerto Vallarta, Vera said.

"They will be deported voluntarily," said Vera. "Their wish is to return to the state of Texas. This is what they have requested."

Families of the victims killed by Couch were relieved that the teen and his mother had been captured, attorney Todd Clement said.

"I think it's particularly satisfying to families that, indeed, it appears that his mother, Tonya, may have committed a crime and may finally be held accountable as well," he said.

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Mark Geragos, a CNN legal analyst and criminal defense attorney, cautioned that it's too soon to say what will happen when the mother's and son's cases end up in court.

"I just think there may be another side to this story," he said. "Before we jump on the bandwagon and do our public lynching, we might want to hold back a little bit and hear what they have to say."

Trial and sentence fueled debate

Couch's sudden disappearance reignited controversy over his case, which attracted widespread attention after a psychologist testified that Couch, who was 16 at the time of the crash, suffered from "affluenza," describing him as a rich kid whose parents didn't set limits for him.

His lawyers argued that his parents should share some of the blame for the crash.

Prosecutors had requested that Couch be sentenced to 20 years behind bars for the intoxication manslaughter charges. The juvenile court judge's decision to put him on probation for 10 years instead of sending him to prison outraged victims' families

It also prompted many observers to question the term "affluenza," which isn't recognized as a medical condition in any formal sense.