(CNN) Ethan Couch, known for the "affluenza" defense in his deadly drunk driving case in 2013, had a "weak positive" result on a drug patch he wore after being arrested Thursday, officials said Friday. His lawyers said he was released from custody.

Couch, 22, was accused Thursday of testing positive for THC on a drug patch, the Fort Worth Star-Telegram reported, citing court records.

A drug patch adheres to a person's skin and can detect drugs that come out in sweat. THC, or tetrahydrocannabinol, is the primary psychoactive component of the cannabis plant.

Ethan Couch booking photo from the Tarrant County Sheriff's Office.

The Tarrant County Probation Office said they "did not have confidence" in Friday's result, according to a statement from the county's Criminal District Attorney Sharen Wilson. At this point, Wilson's office cannot tell if the result was caused by legal CBD oil or illegal marijuana, the statement says.

Couch was released from custody Friday afternoon "pending further investigation and additional testing," his attorneys, Scott Brown and Reagan Wynn, said in a statement to CNN.

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