The autopsy report says Adam Gilbertson died as a result of the combined effects of alcohol, hydrocodone and amphetamine "in combination with possible fresh water drowning."  The 29-year-old's body was found in January by volunteers who were searching for him nearly a month after he disappeared on December 15th. The search was initiated for Gilbertson, a registered nurse, after he never showed up to work after a night out in Denver. Gilbertson graduated from a nursing program in Wyoming in August.