It was a case that captivated the nation, prompting a discussion about wealth and power: A white teenager from a well-off family killed four people in a Texas suburb in June 2013 while driving drunk. At trial, a judge gave the teenager probation after a witness testified that he had suffered from too much privilege — an affliction the witness called “affluenza.”

This month, the case came roaring back after the authorities announced that the teenager, Ethan Couch, 18, had disappeared with his mother before a hearing that could have transferred his case to adult court, possibly resulting in prison time.

On Tuesday, a spokeswoman for the district attorney’s office in Texas’ Tarrant County, Samantha Jordan, said that Mr. Couch had failed to check in with his probation officer on Dec. 10, but that the office was not notified of his disappearance until Dec. 15, leaving the authorities scrambling to make up for lost time.

Mr. Couch’s escape scratched at unhealed wounds in the county, which includes Fort Worth and is near Dallas. “There are two social classes where we live,” said Alexander Lemus, 25, whose brother, Sergio Molina, was thrown from the car driven by Mr. Couch and is now paralyzed, brain-damaged and unable to speak.