It may be something as simple as he was sold marijuana laced with fentanyl. It killed him and the people with him covered it up. I'm not arguing for that as a solution to the mystery but the idea that he crawled in a dumpster is ludicrous and if he committed suicide, the body would have been found. So either he died as a result of an accident that was covered up or someone killed him.
Fentanyl wasn't really a thing in 2006.
The flow of fentanyl into the United States in 2019 is more diverse compared to the start of the fentanyl crisis in 2014