The cause of most hanging deaths is asphyxiation, not broken bones or severed spinal columns. You see those is a hanging with a drop, such as execution by hanging, where very few have that part.
When the person puts their weight on the ligature (rope, wire, cable, sheet, shirt, pants, whatever) it does several things. The airway is blocked, but the carotids are also clamped and stop allowing blood to the brain. This part actually makes you pass out, and then you just can't breathe any more and die.
If the ligature is set too high on the neck, it may not shut off the carotids, which means the subject will then usually fight to keep breathing once they figure out this isn't as easy as they thought. Depending on how they set this up, it may do no good and they die anyway, but sometimes they manage to get loose.
CSI.. I've seen a LOT of hangings.