TOPEKA, Kan. (AP) — A northeast Kansas father and son have been convicted of manufacturing and selling synthetic marijuana through a worldwide network.

The U.S. Attorney’s office says a federal jury on Thursday found 55-year-old Clark Sloan and 33-year-old Jonathan Sloan guilty on 20 counts each. They were acquitted on five other counts.

Clark Sloan lives in Tonganoxie. His son lives in Lawrence, where he was co-owner of a shop where the synthetic marijuana business began.

Prosecutors said the Sloans’ operation involved the manufacture of K2, a substance treated with the active ingredient in marijuana and marketed as an all-natural herbal product.

The enterprise grew to include suppliers, vendors and others throughout the U.S. and in countries around the world. Investigators said the defendants made at least $3.3 million from selling the drugs.