Many Iowa communities report a rise in cases of people becoming badly sick — and in one case dying — after smoking synthetic marijuana. Six people were arrested Tuesday in Des Moines, all charged with possession and delivery of the synthetic drug known as K-2 or Spice.

Des Moines police spokesman Sargent Jason Halifax says investigations involving the drug take time because high-inducing chemicals are being sprayed on legal herbs.  “Part of the problem we’ve had with these investigations in the past is a lot of what’s sold, a lot of this synthetic marijuana is legal to be sold and there’s nothing in there that’s illegal to have.”

This investigation began six months ago and involved four convenience stores. Halifax says during the six months, there have been 53 cases involving synthetic pot, including the death of a Des Moines woman in January.

State laws were enacted to ban K-2 but manufacturers can change up the ingredients, making the “new” drugs legal.