The report obtained Thursday by The Associated Press shows the 66-year-old Jones had severe build-up in his arteries.
Toxicology reports came back negative for any sign of drugs in his system other than cannabinoids, a class of drugs that includes marijuana. However, that played no role in his death.
The report also notes some congestion in the singer's lungs.
Jones rocketed to the top of the 1960s music charts along with his bandmates in The Monkees, captivating audiences with hits including "Daydream Believer" and "I'm a Believer." He died Feb. 29 near his home in Indiantown, Fla.
