I met a homeless man under a bridge in Milwaukee about two years ago. I would regularly visit the local train yard just to look around and find interesting things, and this man probably took the cake in that regard. Anyways, I gave him a bit of food that I had with me and asked what his story was... long story short, he had died at one time due to two veins in his head crossing. He vividly remembers being in a purgatory-like place; stuck between a Heaven and a Hell. After 5 or so minutes of actual death, the doctors had somehow revived him.
Now I'm sure you're thinking about the credibility of a random homeless man, but he was very well composed and had not yet lost his mind. He served in Vietnam, had old worn tattoos to prove it, and also had a collection of old photographs so that he could hang on to the family he once had.