Authorities are investigating whether a teenager who killed four people in a 2013 drunken-driving wreck — and claimed as part of his defense that he suffered from "affluenza" — has fled with his mother to avoid a potential violation of his probation.

Prosecutors said Wednesday they're investigating whether 18-year-old Ethan Couch was one of the people seen in a video posted on social media showing people drinking at a party.

Lawyers for Couch issued a statement saying his probation officer hasn't been able to reach him for several days, prompting authorities to issue the juvenile equivalent of an arrest warrant for the teen.

During his sentencing hearing in December 2013, Couch's lawyers had invoked the affluenza defense that claimed his irresponsible lifestyle was due to wealthy parents who coddled him.