An autopsy report lists marijuana intoxication as a "significant contributing factor" in the death of 19-year-old Levi Thamba Pongi, a native of the Republic of Congo who fell from a motel balcony on March 11.
Pongi's friends told investigators he ate the cookie and "exhibited hostile behavior" that included pulling things off walls and speaking erratically, the report said.
Attempts by the three friends to calm Pongi seemed to work until he went outside and jumped over the balcony railing, according to the report.
Denver police ruled the death an accident and their investigation remains open.
Colorado law bans the sale of recreational marijuana products to people under 21. Possession by people under 21 is also against the law. Authorities said one of Pongi's friends was old enough to buy the cookie from a pot shop.
The medical examiner's office had Pongi's body tested for at least 250 different substances, including bath salts and synthetic marijuana, which are known to cause strange behavior. His blood tested positive only for THC, the psychoactive ingredient in marijuana, according to the report.
One of Pongi's friends also tried the cookie but stopped after feeling sick, said Michelle Weiss-Samaras, a spokeswoman for the Denver County medical examiner's office.
The marijuana concentration in Pongi's blood was 7.2 nanograms of active THC per milliliter of blood. Colorado law says juries can assume someone is driving while impaired by marijuana if their blood contains more than 5 nanograms per milliliter of the chemical.
Officials at Northwest College in Powell, Wyo., say Pongi started taking classes as an exchange student in January. He was studying engineering.
"The Northwest College campus community continues to grieve after Levy's death," the college said in a statement. "All of us were deeply saddened by this tragic incident and feel for his family."