This is a topic that has been on the minds of people for millennia.

I've read Parnia's findings and heard him speak. We may ask the question of whether a person is actually dead if he then comes back into consciousness. In the words of Miracle Max, Princess Bride, maybe he was "mostly dead."

I have written a lot about this, and have published a couple of books tackling this from all angles. Certainly it is the personal sense of self that hopes that death is not the end, because it values its own existence more than anything else. In most cases, anyway.

You asked whether consciousness returns to its source after a person dies. Because consciousness is singular, it does not return to anything. The self, the person, and all of life is contained within it. Thus, consciousness is not contained within the self, so it does not matter whether we live or die, consciousness remains as it has always been. If we change this paradigm around then we can see that it is only the limited sense of self that asks this question (whether consciousness returns to its source), because the self only sees things from its “me”-centered vantage point. If the self could recognize that it is consciousness then it would be obvious that consciousness does not go anywhere and therefore does not come in nor return to anything.