I saw a documentary once about Mormons who practiced something similar to this. Supposedly they no longer do it, but there are some who take Mormonism to the extreme. If I recall correctly, the woman being interviewed said that her uncle killed her husband. They call it a "blood atonement". At the end of the documentary, the woman basically said, "If anything ever happens to me you'll know why." And right after that a message came on the screen that said: Shortly after this interview, she was found dead in her home.
Did anyone else see that documentary?