DULUTH, Minn. (AP) — The owner of a Duluth head shop and three workers have pleaded not guilty to federal charges of selling synthetic drugs that authorities say were misbranded and marketed as incense, potpourri or bath salts.

Last Place on Earth owner Jim Carlson and his employees entered their pleas Friday in U.S. District Court in Duluth.

A federal indictment unsealed this week charges Carlson, of Superior, Wis., and his employees with conspiracy to violate federal regulatory laws and conspiracy to distribute controlled analogue drugs. Also charged are Lava Haugen of Superior and Joseph Gellerman and Jamie Anderson, both of Duluth.

Prosecutors claim the synthetic drugs are illegal. Carlson claims the products he sells are legal.

A jury trial for Carlson and his employees is scheduled March 11.

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