Texas prosecutors have said Tonya Couch will be charged with hindering the apprehension of a juvenile, and if convicted, faces between two and 10 years in jail.
A Mexican immigration official with knowledge of the case said Ethan Couch's attorneys had filed a writ to seek protection and block his deportation. If the teen confirms his wish to go forward with that approach, the case would go to trial, and proceedings could take months, the official said.
"At this time we do not have a time frame. We do not know if the Mexicans have the highest priority on this case like we do here in America," Chief Deputy U.S. Marshal Richard Hunter told reporters Wednesday. "It's on their time schedule. We've seen these things happen as quickly as two weeks to two months."
The law caught up with Ethan Couch, 18, and his mother in Mexico on Monday after the pair went missing earlier this month.
He was on probation for killing four people in a drunk driving accident in 2013
, when he was 16. At the time, many were outraged that a judge sentenced him to probation instead of jail time, slamming his now-notorious "affluenza" defense.
Even if a Mexican immigration court does decide to send Couch back to the United States, he might not face much time behind bars.
Violating his probation by fleeing to Mexico may earn Couch a maximum of 120 days in jail, said Tarrant County District Attorney Sharen Wilson.
Anderson told CNN Wednesday that the punishment, which he considers lenient, is infuriating.
"He doesn't believe the rules apply to him, he doesn't believe the laws apply to him," the sheriff said.
Adult or juvenile
What kind of justice Couch could face this time will depend on whether he is treated as an adult or a juvenile for his alleged probation violation.
Prosecutors want to see Couch in an adult court, but because the alleged violation happened in the juvenile system, Couch effectively would start with a clean slate in the adult probation system. As a result, the adult court judge could not punish Couch for violations he committed as a juvenile.
The maximum he could get would be 120 days. But if he is treated as a juvenile, the sentence would be lighter, Wilson said.
Anderson said he supports the district attorney's request to transfer Couch's sentence from the juvenile system to the adult court system. Even if the time behind bars is short, the requirements for probation as an adult are much more strict than for juveniles, he added.
Though he's an adult now, Couch was 16 when he was sentenced for the original crime. If he is punished for a violation in the juvenile probation system, that would have him in jail until his 19th birthday on April 11, 2016, about 102 days.
But moving Couch to the adult system holds a potential advantage for prosecutors. If he ends up on adult probation and violates that, he could land in jail for up to 40 years, Wilson said.
He also could get more time on top of that, if he is convicted of new crimes as an adult.
It wasn't so much Ethan Couch's original crime that drew the nation's ire as it was the punishment doled out for it.
In June 2013, Ethan Couch plowed into a stranded motorist and three people who were helping her. All four were killed.
Two people riding in the bed of the teen's pickup were tossed in the crash and severely injured. One is no longer able to move or talk because of a brain injury, while the other suffered internal injuries and broken bones.
Three hours after the crash, tests showed Couch had a blood alcohol content of 0.24, three times the legal limit, prosecutors said.
Prosecutors wanted to see Couch behind bars for 20 years, but instead he was sentenced to probation and rehab.
During the trial, a psychologist testified that Couch suffered from "affluenza"
-- he was the product of wealthy, privileged parents who never set limits for the boy.
Caught drinking again?
The sentence and that term triggered widespread outrage, and the Couches' alleged fleeing has drawn attention back to his case.
In mid-December a warrant was issued for Couch
to be taken into custody after his probation officer couldn't reach him. He appeared to have dropped off the radar after a video emerged that allegedly showed him at a party where alcohol was consumed.
Couch had been ordered to stay away from drugs and alcohol for the duration of his probation.
The U.S. Marshals Service tracked Couch to Mexico 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 were found in an apartment in the Pacific resort city of Puerto Vallarta, and Couch had changed his look. His normally reddish blond hair and goatee were dyed a dark color.
It's unlikely the pair had gone to Mexico for a vacation, said the sheriff, Anderson.
"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," Anderson said.
The pair entered Mexico as tourists and exceeded their allowed length of stay. When captured, they were turned over to the custody of immigration authorities in Puerto Vallarta.
Tuesday, a representative in Jalisco state for Mexico's National Institute of Immigration said the Couches would be "deported voluntarily."
"Their wish is to return to the state of Texas. This is what they have requested," Ricardo Vera said.
Since then, Ethan Couch apparently changed his mind.
He was moved Wednesday to an immigration holding facility in Mexico City where he will be held during his legal proceedings there, a Mexican government source said.
Victims' families relieved
Families of the people killed by Couch were relieved the teen and his mother were 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.
Kevin McConnell, whose son Lucas -- 12 years old at the time -- was injured in the crash caused by Couch, was happy at the news of the detentions, but confounded, too.
"Oddly enough, my first reaction was, 'Really? Puerto Vallarta?'" McConnell told CNN's New Day Wednesday.
Of all the places to hide, McConnell said, the popular resort town seemed like the latest in a string of bad decisions made by mother and son.