Police admit they're still looking for the 18-year-old "affluenza" teen and his mom

By Chris Harris
December 22, 2015 04:30 PM

Authorities in Texas tell PEOPLE they’re no closer to apprehending Ethan Couch, the 18-year-old who famously avoided jail time after killing four people in a 2013 drunk driving crash by claiming his privileged background rendered him unable to comprehend the consequences of his actions.

But police have added Couch’s mother’s name to the nation’s list of missing persons, according to Tarrant County Sheriff Dee Anderson.

Anderson says investigators believe Couch and his mother, Tonya, went on the run not long after prosecutors filed court papers last month seeking to have his criminal case moved from juvenile to adult criminal court.

Anderson claims a call from Tonya’s mother prompted the sheriff’s office to list Ethan’s mom as missing.

On Monday, police released information about Tonya’s missing 2011 black Harley-Davidson edition Ford F-150, which bears Texas plates BC5 0945.

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“We don’t know if they are in it for sure, but we want to know where it is at least, because we haven’t been able to find it,” Anderson says of the truck. “We all strongly suspect they are together and that she is helping him. It would be a huge leap coincidence if they disappeared at the same time and are not together.”

Anderson says that if it is proved Tonya is helping her son, he’ll make sure she faces a judge.

“I can’t prove she is with him or helping him, but when we can prove it, criminal charges will be filed,” Anderson tells PEOPLE. “She will answer for that, if I have anything to do with that. If there is any indication she is aiding him, we will pursue her as hard as we can.”

Dubbed the “affluenza” teen by the media, Couch has been missing for more than a week.

Couch is wanted by authorities for allegedly violating the terms of his 2013 probation, which prohibits him from consuming alcohol.

A six-second video surfaced on social media last month, allegedly showing Couch at a party, involved in a game of beer pong.

The video immediately sparked an investigation into whether Couch had violated his probation.