If one wanted to be technically pure about it, the plane would have to hit precisely vertical to not go very far, and with the amount of energy having been converted from a Potential energy of 3000' to virtually sea level in under half a minute (check the radar returns) it would create a crater.
As pointed out before it sounds more like a spiral dive. Hence it had a small horizontal component.
To call out the so called evidence of PeterC and yr right, please explain your theories. Actually maybe better not.
There were no signs of performance issues (ignore the usual witness reports), no radio broadcasts of any issue or distress, easy glide to beach or water away from houses and what certainly looks like a spiral dive under power (known).
Draw your own conclusions to the above but it does not sound like your average CFIT does it, nor engine/mechanical failure.