The first set of witnesses observed the airplane with the engine sputtering. They observed the left wing drop and the nose pitch up. The right wing then dropped,
This report makes it appear that the pilot did not continue to fly the aircraft after the engine produced less power.
So, the cause of the fatality was a crash. The cause of the crash was failure to maintain flying speed following a loss of power. The cause of loss of power was misfueling. The cause of the misfueling included inattention by the pilot.
A departure toward the built up area looks like it would be messy to force land into, but not necessarily fatal, if the aircraft returned to earth under control.
If the fuel were correct, would there have been a crash? Probably not - this time. But, the underlying fact seems to be the the pilot did not continue to fly the plane. Any number of other anomalies could put that pilot in a position where "flying" the plane was immediately required.
I'm going to have a look at Mary's EFATO thread. After a bit of research, I'll have some comments on "best glide speed" as it relates to EFATO....