The cause of death for a University of Wyoming student found dead in January has been determined.

According to a police release, 18-year-old Triston Harvey’s death has been ruled an accident. Harvey, of Gillette, was found dead in Laramie during the early morning hours of January 31, 2015.

Police say the cause of his death has been determined to be brain injury caused by lack of oxygen after his heart stopped. They say the use of synthetic LSD and a moderate case of premature atherosclerotic cardiovascular disease are listed contributing factors in his death.

According to the release, the toxicology report was positive for two synthetic hallucinogenic drugs, 25C-NBOMe and 25I-NBOMe, which are often referred to as synthetic LSD.

In 2013, the DEA classified both compounds as Schedule I controlled substances under the Federal Controlled Substances Act.

Police waited to release Harvey’s cause of death until after they received results from his toxicology report.