There are other books now. Mark wrote his MUCH too hastily, no doubt at the urging of a publisher to be the first on the market. He didn't even wait for the autopsy report. It had a few insights, but I agree, it was somewhat disappointing.
If you are going to read more, I recommend Diana Lynne's book next: "Terri's Story -- the court-ordered death of an American woman." It is well researched and written, loaded with factual material.
