Um... Kinetic energy is absolutely what does the killing when dealing with ANY object in motion, be it a bullet or a tractor-trailer. When a Peterbilt hits a deer at 70 mph, I can assure you that it's the kinetic energy that the truck has by virtue of being a mass in motion that splatters that deer all over the concrete.

Without kinetic energy the bullet would be useless. It's the kinetic energy that provides the force to to the work of punching the aforementioned hole in the deer, which is ultimately what kills it. No KE, no hole, no dead deer.

Mike