And, now for something really important!
Like it or not, I am seriously considering writing briefing on the Court's having sustained the prosecutor's objection to Dr. Egstrom's testimony relative to the deceased's air consumption. As a diver, I understand the mechanics. As a lawyer, I understand the relevance and the arguments about how it was prejudicial error. I will send a draft to SadiesMom outside of the forums and perhaps she will provide it to David's attorneys. It may save them time and fees.
For K_girl's reference, it has nothing to do with nitrogen loading. Here is the idea. Log entries from prior dives can give us a pretty good idea of a diver's SAC. We can compute SAC if we know (1) how much gas the diver started with, (2) how much gas the diver ended with, (3) how big the tank was, (4) the average depth of the dive, and (5) the duration of the dive. If instead of numbers 4 and 5, we have a dive computer that gives a profile of past dives, all the better.
If we do not have number 1, it is reasonable to assume a standard starting pressure of 3000 pounds. If we do not have number 2, it is reasonable to assume the dive ended with 500 pounds. If we do not have number 3, it is reasonable to assume an AL-80, since it is the most common size tank.
In any event, these three items tell us how many cubic feet of gas a diver has used on a dive.
Applying that to the depth and time provides us with an SAC for the diver.
If we have this information for a number of dives, we can get a pretty good idea of the diver's SAC.
Now, we should be able to tell how much air the deceased used before she died. This is the difference between the start pressure (probably 3,000 pounds) and what was left in her tank at the time she died, divided by the start pressure, multiplied by the size of the tank.
It is reasonable to assume that the deceased entered the water and descended to the bottom reasonably promptly. We should know the depth from her computer. The depth divided by 33 and multiplied by the SAC will tell us how much gas the deceased was using per minute. Dividing that figure into the total gas used tells us how long into the dive the deceased stopped using air, i.e. died.
It is sort of like saying a car gets 15 miles to a gallon of gas and used 5 gallons of gas: We know it went around 75 miles even if it was not in a straight line.
Now, if the deceased died x minutes into the dive and David's computer were to show that at that point in the dive, he had already returned to the boat, that would be pretty good evidence he did not do it. Even if David was not in the boat or on the surface, if x was after a point that David said he had parted company from the deceased, and the time stamp on his photos proved it, that would support the conclusion he did not do it.
Recall that the jury, to find David guilty, had to both believe the prosecution's evidence and disbelieve David's denial of guilt (assuming the testified in his own defense). As far as disbelieving David's denial of guilt, if his testimony placed him with the deceased within the same time frame as the prosecution's experts testified that the deceased died, that would tend to cast doubt on David's credibility. That is, either he lied about when he left the deceased or about not being with her at the time of her death or both. However, if the time frame were different, that might not cast doubt on David's credibility and therefore might not impeach his denial.
(Pretty good for explaining this without a lot of editing, huh?)