A person who is brain dead looks like they are unconscious or in a deep sleep. The eyes are usually closed, there is no purposeful or spontaneous movement, and if he is on a ventilator, his chest may rise and fall while the machine breathes for him. Because the ventilator is bringing oxygen into the body, the heart will continue to beat pumping blood through the blood vessels, so the skin may still be pink. The skin will still be warm to the touch. Judging casually by external appearance alone, it may be difficult to tell that the person is dead. Even to a medical professional, a brain dead person on a ventilator may look surprisingly like a living person even though they are not alive. That is why the determination of brain death is so carefully documented and confirmed with appropriate testing.