If Wecht was suspicious of the methadone he would've discussed that with his "employers" HKS and Anna? You've gotta figure he did. And then you would think, Anna and HKS would in turn demand an investigation by the Bahaman officials. But they didn't. So this makes me think that Howard convinced Anna not to demand an investigation. Maybe he convinced her that Daniel was on methadone and not to think her son was such a saint. That maybe he had taken some of hers or HKS's methadone that was in the hospital room.
You'd think he would have discussed it with them or the attorneys. I remember he said it wasn't his job to investigate where the methadone originated from or how Daniel got it- that it was "the media's job." Perhaps meaning it was the media's job to find out why the Bahamians didn't seem to be investigating further ( if they weren't), cover-ups, unscrupulous doctors, Anna or Howard?
The fact that it appeared Anna wasn't demanding further investigation into Daniel's death always told me they knew how it happened, and that it was, as Wecht has said, a tragic accident.