FORT WORTH, Texas, Jan. 28 (UPI) -- Ethan Couch was returned to the United States Thursday after spending more than a month in Mexico after his arrest on a probation violation, authorities said.
Couch, known as the "affluenza teen," was finally deported by Mexican authorities this week and arrived at Dallas-Fort Worth International Airport Thursday morning. He was then transported to a juvenile detention facility after his arrival, officials said.
"He's very calm. He was very quiet, very passive -- not at all argumentative or resistant," Tarrant County Sheriff Dee Anderson said of Couch upon his arrival.
Couch's attorneys had been fighting deportation from Mexico, but finally dropped the effort.
Couch is being held for an alleged probation violation related to a 2013 crash that killed four people in Burleson, Texas. Investigators say Couch, who was 16 at the time, had a blood-alcohol level three times the legal limit.
"We anticipate that the Court will lawfully transfer his probation to an appropriate Tarrant County District Court with adult criminal jurisdiction. Under the law, the transfer will become effective upon Ethan's nineteenth birthday in April," his attorneys said in a statement released to ABC News Thursday.
It isn't clear yet whether authorities will try and prosecute Couch in adult court or let the case play out in the juvenile system.
Investigators say Couch and his mother, Tonya, fled to Mexico late last year after the teen potentially violated his probation. A video online purportedly showed him drinking, which would constitute a violation of the 10-year probationary sentence imposed by the court. Police arrested him and his mother Dec. 28 in the Pacific resort city of Puerto Vallarta.
Tonya Couch has since been charged with hindering the apprehension of a felon.
Thursday, his attorneys said Ethan Couch will cooperate with authorities and "successfully complete his term of probation."
During the sentencing phase of the drunk driving trial, a defense witness claimed Couch suffered from "affluenza" -- a condition he said results in irresponsible behavior in part due to living a wealthy lifestyle.