For those of us who have been around General Aviation for a good few years there is very little mystery as to the technical reasons for this accident, your last post talked of the aircraft shaking, this could quite easily have been the engine being difficult to start, this is not at all unusual with the larger injected engines.
Many above have described how a pilot without any formal instrument qualification decided to cruise an aircraft designed to fly much higher at the perfect altitude to accumulate ice and a then decided to descend ( probably a under marginal control ) to melt the ice. It’s hardly a surprise that under these conditions the aircraft was flown into the sea ether unable to maintain altitude due to the accumulated ice of because the pilot exceeded his skill level and lost control.
If you want to get to the truth of the matter the technical issues are of little relevance because they are merely the logical conclusion to the actions of a trail of people who have decided to cheapskate on transport and who commissioned an unqualified pilot to fly and aircraft that his licence and experience did not allow him to fly safely.