Sounds like some sort of human sacrifice.
If the brain is still functioning, the person is ALIVE!! Whether he or she has any chance of recovering to society's measure of functionality is beside the point. You don't harvest necessary organs from someone who is still alive.
They will not do it 'live'; perhaps like the Chinese do it. . .a gun; at the base of the skull; and with a silencer. THEN. . .they harvest. . .