no one can be sure of the death or near death experience in a definitive absolute way unless and until they have experienced it first hand. a coupla items though. when an individual is dying, hearing is the last thing to go. the death rattle begins and usually the feet turn slightly inward. eyesight is no more. they can still hear which gives those around them the opportunity to say their final farewells. finally, life stops with the last breath. the heart monitor goes flat, and that is that. time to call the body removal team........

here's a link for more info....

http://en.wikipedia.org/wiki/Death_rattle