The autopsy report stated that Martin had trace levels of THC, the active ingredient in marijuana, in his blood and urine.[137][138] The toxicology report found the levels to be 1.5 nanograms/ml of THC and 7.3 nanograms/ml of THC-COOH, a metabolite of THC that can stay in the system for weeks after cannabis has been smoked.[137][138] Larry Kobilinsky, a professor of forensic science, stated that the THC amount was so low that it may have been ingested days earlier and played no role in Martin's behavior.[139]