I think it is important to understand that CBS is in the business of making money and the TV show "48 Hours Mystery" is in the business of telling a story that is interesting to TV viewers.
That is correct. That is why both Dateline and 48 Hours were interested in the case from the start - because there was never any clearcut way to determine David's guilt - in a situation where his innocence was supposed to be presumed.
I also understand that there were some e-mails from Swain to this "soulmate" back home stating that his situation would be changing soon. These e-mails were allegedly sent shortly the death of his wife.
Really? This is the first I've heard of this and I know David and his family fairly well. I don't claim to have been aware of 100% of the evidence, but I'm completely unaware of these alleged e-mails. Where did you get this information? I'd really love to see a source for this. Maybe I'm just out of the loop...
The judge likely didn't want to hear the debate about air consumption because it wasn't relevant. Only one other diver was in the water when the victim died and that person was found GUILTY of murder.
Actually, at the time SHE (i.e., the judge) ruled that David's expert's testimony on the air consumption wasn't admissible because he was a Ph.D., not an M.D., David had not yet been found guilty of murder. So if your supposition was the case, then her decision to rule out his expert's testimony would have been highly prejudicial. Perhaps had she allowed David's expert's testimony about air consumption and David's psychologist's testimony (also because he was a Ph.D., not an M.D.) to be heard by the jurors, he would NOT have been found guilty of murder.
There was also a great deal of information left out of the 48 Hours piece - the botched, substandard autopsy (standard tests any coroner in the US would do in an aquatic death plus not following up on findings like the 22% blockage in the descending coronary artery with a tissue sample to see if Shelley had *had* a heart attack), some of Shelley's medical history that could have been relevant, the fact that the dive gear wasn't stored in police custody, but in the custody of a dive shop operator who had a vested interest in making sure that there was nothing wrong with the air in the rented tanks - again - something that is not standard in the US because there's no way to safeguard the integrity of the equipment's condition and other a few more things.
In any case, there is an appeal in the works - and there is another much longer thread on this subject. In that thread, an attorney who works on Tortola has said that he would not be at all surprised if David's verdict were overturned on the appeal. Several other attorneys have expressed that opinion to me as well, after hearing the judge's summation to the jurors. Not being an attorney myself, I don't know the legal issues as to why they feel that way - I only hope that they are correct.