Paul: I'm one of the major adherents to the belief that Jack Thayer's "suicide" and its ascribed motives were a rather hasty call. The circumstances surrounding his death seem peculiar in a few ways -- to me, at least. And with Pennsylvania's then Lieutenant Governor, as friend of the family, having been directly involved in some of the investigative decision-making, I don't think it's at all inconceivable that a more exhaustive investigation might have been stifled, for better or worse.
As for any direct suggestion of murder (or more generally, homicide), I suspect it's entirely possible from what I've found, though I certainly wouldn't want to just venture a guess as to a culprit or motive. The one thing that's reasonably clear to me from the news accounts is that certain details and the questions that might otherwise have arisen from them seem to have been glossed over far too quickly.
I sent Phil Hind a second version of Jack Thayer's obituary and two follow-up articles a while back -- from the [Philadelphia] "Evening Bulletin" -- which include additional details of the discovery and aftermath, though I don't know if they've ever made it to the ET biographical section. (If not, and there's interest, I'll just post them here.)