There are differing definitions of death, but it is clear that if a person is unconscious, their heart has stopped and their brain ceased to function, that person has died. They are beyond resuscitation, and their body, now just an object that resembles a person, meets none of the criteria for life. The body is no longer a series of self-sustaining chemical reactions; through the same miraculous processes that allowed it to live, it will begin an inexorable return to the ecosystem from whence it came.
Following death, pallor mortis is the first stage in the process of post-mortem disembodiment. As the heart has stopped, blood no longer circulates, and the red blood cells (being denser than the plasma) drift downwards, away from the upper surface of the body. This is the cause of the paleness of dead skin, and happens within the first half-hour of death.
The Universal Blog 