Switched cups in the hospital room is the hypothisis most of us here have. Reason being we know he brought her drugs in California when she was in the hospital drying out, makes sense that when he went out for food and drinks he spiked her drink with her normal drug quotient and Daniel accidentally (or on purpose) drank from the spiked cup.
But now, the motive is becoming more clear. I beginning to believe there may be a few witnesses in the inquest into Daniel's death, that aren't going to be good for HK$.
What an asshole! She's trying to dry out, and the bum smuggles drugs to her? The switched cup theory is a valid one. I'm still trying to figure out why Daniel turning 21 would be a reason to off him, though. I have heard about the contents of Anna's will, and I don't recall if there was a clause regarding Stern's control of her assets being nullified if and when Daniel became of age.