A couple of ways off the top of my head. I think
@TLDR20 and
@Blizzard are private pilots, so they'll know more than I. Something causing the aircraft to lose speed and stall, center of gravity too far aft, icing adding weight and degrading lift generated by the wings.
Blancolirio (A former Air Force and current American Airlines pilot) has a great breakdown of the crash and video (as he always does for aircraft accidents). As mentioned earlier, a spin in a T-tail a/c is basically a guaranteed crash. He's leaning towards icing as a probable cause.