Drug abuse expert witnesses may testify on testify on DUI, intoxication, chemical dependence, illicit drugs, and marijuana, as well as related issues. The Colorado Department of Public Health and Environment is investigating the deaths of three people and the hospitalization of 75 others who may have smoked synthetic marijuana. Synthetic cannabis is a psychoactive drug made from natural herbs and then sprayed with synthetic chemicals. the product is marketed as “herbal incense” and “herbal smoking blends.”