Going from memory.
As I recall, Denver had a problem with alcohol, and had been in trouble for mixing alcohol and AV/GAS. While he had periods of sobriety, there was some suspicion that he had been drinking prior to the fatal crash, and the resolution seemed to respect that whether he was or not was irrlelevant.
That's memory, it's not worth researching, and I'm pretty sure it's correct.
Arf