Federal authorities have joined Texas officials in the search to find and apprehend missing “affluenza” teen Ethan Couch, who went missing this week.

Late Thursday afternoon, Tarrant County Sheriff Dee Anderson said U.S. Marshals and the FBI officially joined the search to find Couch, KXAS 5 (NBC) reported. Texas authorities issued the order to apprehend Couch, who made national headlines after killing four people in a June 2013 drunk-driving accident. He went missing this week and is now believed to be on the run. Couch and his mother stopped communicating with his probation officer and appear to have abandoned their home. Local officials believe Couch may have fled with his mother following a possible violation of his probation.

Anderson tweeted to the public for help in locating Couch, asking anyone with information to contact the Sheriff’s office.

Couch was 16-years-old at the time when he drove drunk and killed four people in a car accident in Burleson. His blood-alcohol level was three times the legal limit for an adult and there were traces of Valium in his system. Instead of jail time, Couch was tried as a juvenile and sentenced to the 10-year probation sentence that included time in a rehabilitation center as part of his “affluenza” defense.

Affluenza is defined as “a psychological malaise supposedly affecting wealthy young people, symptoms of which include a lack of motivation, feelings of guilt, and a sense of isolation,” a condition claimed by Couch’s defense team resulted in his irresponsible behavior caused by having wealthy parents who coddled him and hindered his ability to know right from wrong.

Tarrant County investigators began searching for him early Wednesday after Couch’s probation officer could not reach him or his mother for several days. Now 18-years-old, Couch is in the second year of serving a 10-year probation sentence that included rehab and counseling. Although legally an adult, Couch’s case remains in juvenile court because the offense happened when he was a minor.

His most immediate problem is that he ditched probation and his probation officer could not find him, which prompted the “directive to apprehend,” a term used in juvenile cases that is the equivalent to an adult arrest warrant. However, another potential problem surfaced. A social media video posted earlier this month and showed what appeared to be a teenager who resembled Couch at a party where alcohol was consumed. Among the violations of his probation are driving, drinking or doing drugs, KXAS 5 (NBC) reported.

Tarrant County District Attorney spokeswoman Sam Jordan told the Fort Worth Star-Telegram Couch faces a prison sentence of up to 10 years if he is found to have violated the terms of his probation. She said that investigators with the county’s Juvenile Services and with the D.A.’s office continue to search for the Couch and his mother, Tanya.

Prosecutors must determine if Couch was one of the individuals drinking alcoholic beverages at the party. The video itself would not necessarily be a probation violation, Dallas attorney Nicole Knox told KTVT 11 (CBS). “The state would have to prove that this was him in the video and it was taken at a time and occurred at a time that was during his probation instead of before it,” she said.

The Tarrant County Sheriff previously confirmed for the local NBC affiliate that Couch missed an appointment with his probation officer and, while that is not uncommon, what was not a good sign was when juvenile services went to speak to Couch, they could not find him or his mother. Anderson believed Couch’s disappearance was planned following the release of the video.

Anderson told KTVT 11 he was not aware of any travel restrictions for Couch but would not be surprised if the Couch was no longer in the country. He said: “I’ve got a bad feeling that he’s gone and I don’t think he’s gone a short distance.” The sheriff added that the “affluenza” teen is the top fugitive his investigators are trying to find. No arrest warrant was issued for his mother but Anderson said they are looking for anyone who may be with him or helped him leave the area.

Follow Merrill Hope on Twitter @OutOfTheBoxMom.