From the eyewitness reports it seems the Apache encountered a
systems failure in flight that rendered a return to base
not viable. From the spiral flight downwards path taken before the
crash landing we can infer that the helicopter was either
autorotating after an engine failure (gliding), or had a tail rotor
malfunction, rendering forward flight impossible.
The landing was probably not as hard as a crash,
but perhaps more of the fact the pilot might have flared
the helicopter just before touching down and causing a
tailstrike... we can see from the still-extended wheel bogeys and
general intactness of the fuselage that the impact to the forward
part of the fuselage was somewhat mitigated, perhaps by
the tail strike.
It is difficult to infer travel of the aircraft following impact
(it might have rolled forward) due to the lack of pictures in
the appropriate angle to show ground marks, but if
it did then it explains why the tail rotor was found a
distance away.
I do not think it's likely that the tail rotor snapped off in
flight, the results of such a catastrophic failure is
usually such that the aircraft is virtually uncontrollable, and
certainly almost impossible to put down with such minimal damage to
the forward airframe as indicated in the pictures.
My analysis from the pictures.
