I saw an expert video interview yesterday. It is very likely that the plane iced up and the pilot did not notice it in time leading to a stall. The stock auto pilot on those planes does not manage the throttles. So if the auto pilot was engaged then it could have kept pitching the plane up(Trying to maintain altitude) causing a loss of air speed until it stalled. It is up to the pilot of monitor the throttles and air speed. There were ice warnings in the area he was landing.
Interesting.
His landing destination was Anoka Airport, next town over from where he crashed. Wouldn’t seem likely to be on autopilot in a landing approach, unless he was not in control for some reason.