A man arrested for marijuana possession was found with an unknown synthetic drug in a jail search Saturday night at the Walker County Jail.

Huntsville Police officer Casie Wheeler was on patrol in the 500 block of 11th Street around 6:30 p.m. Saturday, when she noticed a vehicle with expired registration and a missing front license plate. While approaching the vehicle, Wheeler heard passengers say, “hide it” and also smelled the odor of marijuana.

A report said that Wheeler noticed empty beer bottles and realized that the smell was coming from the rear passenger – identified as Darius Wilson, 35, of Dallas. Wilson admitted to having a marijuana cigarette, but when Wheeler searched Wilson’s backpack, she found two ounces of marijuana and placed him under arrest. No other passengers in the vehicle were charged.

When Wilson arrived at the Walker County Jail, he was found with a plastic bag containing a powdery substance. Police say tests of the substance were negative for cocaine.

“This was great work by officer Wheeler to follow her instincts and make the arrest,” HPD Lt. Jim Barnes said. “We are not sure what the drug was, but there are so many synthetic substances made in foreign labs which change molecules slightly and it is hard for police to keep up.”

Wilson was arrested and charged with possession of marijuana and possession of a controlled substance. He is currently being held in the Walker County Jail on $4,500 in bonds.