On Wednesday, the U.S. Drug Enforcement Administration announced it was extending the ban on five chemicals used to make Spice that mimic THC, the active ingredient in marijuana. Sellers or users often spray or sprinkle the chemical on plant material, then smoke it, according to the DEA. The DEA has classified the chemicals as Schedule 1 controlled substances, meaning they have high potential for abuse and no currently accepted medical use in the U.S.

Distribution of Schedule 1 substances is a felony, Walsh said.

Prosecution can be difficult because those who make these chemicals can alter them slightly to make them technically legal, he said. “The bad thing then is that people say this stuff is safe, it’s not illegal, and the reality of the world is that the scientists who’ve created this stuff stay one step ahead of law enforcement.”

An entire police patrol team and nearly half the department’s detectives have been interviewing patients and investigating the source of the drug, he said.

No one had been arrested as of Thursday afternoon, he added.

Bob Harrington, director of the Casper/Natrona County Health Department, said the case began Sunday when a person went to the Wyoming Medical Center with reported kidney failure.