What exactly is the prosecutions "list" they accept as proof for Merediths TOD?
You can read the "reasoning" for yourself on pages 177-179 of the Massei report translation PDF on the PMF site.
Chris C's summary is honestly not all that far off the truth.
Massei starts by acknowledging Dr Lalli's evidence that if indeed all of Meredith's 18:00-18:30 meal was still in her stomach you would expect gastric emptying to have begun by 22:00 at the very latest. (On this point Lalli seems to have been a little out of step with the latest papers, you might say, which all indicate a shorter t(lag), but even so Lalli's view is sufficient to break the prosecution case).
Then he seizes on Dr Lalli's qualification that such measurements are imprecise to a degree, and takes that to mean that it's absolutely open slather and there's no reason the time of death can't be 23:30. This is once again akin to hearing that a police officer's radar gun has a margin of error of 5kph, and jumping to the conclusion that a reading of 100kph could really mean a speed of 30kph.
Perhaps realising this is a bit thin, Massei then references the testimony of Professor Ronchi who (incorrectly, as it turns out) asserted that Dr Lalli had not tied off the bowel as is normal in an autopsy, and floated the idea that the reason there was absolutely no food in the upper bowel was because Dr Lalli was so utterly incompetent that he had squeezed all the food in Meredith's upper bowel all the way down to the very bottom of her bowel accidentally while trying to examine it. Since the autopsy video apparently clearly shows Dr Lalli tying off the bowel properly, we can dismiss this idea.
Anyway, having thus magically handwaved away the lack of food in the duodenum, Ronchi was able to switch from establishing time of death based on when stomach emptying begins (or t(lag) in shorthand), to trying to establish it based on when it finishes. This, oddly enough, is exactly the manoeuvre several guilters right here have tried, except that lacking Ronchi's expertise they didn't realise that they needed to explain away the lack of food in the duodenum.
Then they quote Professor Cingolani who said that estimating time of death by stomach contents can be off by more than twelve hours. In this Massei is almost certainly taking Cingolani wildly out of context, because t(lag) simply does not vary by twelve hours either way. Most likely Cingolani was speaking more generally about trying to estimate time of death based on the degree to which a digested meal had progressed through the bowels, and Massei took him out of context as it suited him.
Then he lastly adds that maybe Meredith had a sip of wine and a mushroom when she got home, and that this adds even more uncertainty.
Then he concludes that Meredith thus could have died at absolutely any old time and continues merrily on his way. That's it.
There is absolutely nothing in Massei's reasoning to refute the argument that if Dr Lalli tied off Meredith's bowel correctly during the autopsy, then it follows that Meredith died before 22:00 at the very latest. Dr Lalli tied her bowel off correctly. Therefore she died before 22:00. Game over for the prosecution theory.
