So-called 'Affluenza teen' released from prison

FORT WORTH, Texas -- The so-called Affluenza Teen, Ethan Couch, has been released from prison.

RELATED: 'Affluenza' mom Tonya Couch arrested days before son's release from jail

Couch served two years in prison for violating his probation. He was 16 years old when he killed four people while driving under the influence in 2013.

Couch's attorneys argued his wealthy upbringing made it impossible for him to understand the consequences of his actions.

RELATED: 'Affluenza' Teen's Dad Guilty of Claiming to Be Officer

Couch will be required to wear an ankle monitor while finishing his probation.

A Texas judge revoked bond for his 50-year-old mother.

RELATED: Report reveals Mexican authorities detain 'affluenza' teen Ethan Couch

Tonya Couch was booked into the Tarrant County jail on March 28. Court documents show that she failed a urine test required as a condition of her bond but don't specify the substance the urinalysis revealed.

State District Judge Wayne Salvant had warned Couch last June to "use common sense" pending her trial on hindering apprehension of a felon and money laundering charges. She was charged after she and son, Ethan, fled to Mexico in 2015.

The Associated Press contributed to this report.