Sunday, July 1, 2012
The time of death in the murder of Meredith Kercher
Part 33 in the Knox/Sollecito case
The time of death (TOD) in the murder of Meredith Kercher is a central part of the question of whether Amanda Knox and Raffaele Sollecito participated in her murder. Ms. Popovic saw Ms. Knox around 8:40 PM acting normally. If the TOD is between 9 and 10 PM on 1 November 2007, then it is difficult to imagine how they could have imbibed drugs or alcohol, met Rudy and initiated events leading to murder in the 80 minutes that followed. Let us examine the TOD primarily using the physiology of digestion. This topic was recently discussed at the pro-guilt website, True Justice for Meredith Kercher, and I am grateful to its author for reminding us of the sensitive nature of this topic. I am also grateful to the translators of the Massei-Cristiani Report and the Hellmann-Zanetti report.
Meredith’s friends’ descriptions of the meal
As summarized in the English translation of the Massei report (pp. 34-38), Robyn Butterworth was not sure about when the young women ate pizza on 1 November but thought that might have been around 6 PM. They stopped watching the movie, “The Notebook” long enough to put the dessert, apple crumble, into the oven, according to John Follain's book, "Death in Perugia," p. 54. Amy Frost thought that the time of the meal was 5:30 or 6 PM. Sophie Purton thought that the time of the end of the meal was perhaps an hour before leaving, which would mean that they finished desert around 7:45. According to Candace Dempsey’s book, Murder in Italy, Sophie Purton said that Meredith ate only part of her pizza.
Judicial estimates of Meredith’s time of death
Massei and Cristiani, the professional judges in the first trial, put the time of death as a few minutes after 11:30 PM (p. 382). Follain (Death in Perugia, p. 344) reported that PM Mignini estimated the time of as between 11:20 and 12 midnight. A summary of Raffaele’s appeal document suggests a TOD of 9:30-10:00. Hellmann and Zanetti, the professional judges in the second trial, put the time of death as no later than 10:13 PM.
Gastric emptying times
The contents of Meredith’s stomach had a volume of 500 mL, and her duodenum was empty (Massei, p. 115). Two time periods are commonly used to measure the first portion of digestion. The time at which food begins to leave the stomach and enter the duodenum is t(lag). The time it takes for the stomach to empty by half is t(1/2). Because Meredith’s duodenum was empty, the more useful number is t(lag), not t(1/2). The time between the start of Meredith’s last meal and the TOD must be less than t(lag). In some of his comments Judge Massei seems to be concerned with t(1/2) or perhaps the time it take for the stomach to empty completely. Yet he also wrote (p. 115), “Dr. Lalli also took into consideration the state of digestion. He stated that solids are ingested into the stomach and are not able to reach the pyloric sphincter until they are reduced to a semi-fluid or fluid consistency; the emptying of the stomach then begins to occur when some of the contents have become sufficiently fluid to reach the pylorus, which happens the third or fourth hour after eating. This is when one can find food material at the level of the duodenum (page 63 of the Lalli report).” This is significantly longer than the average or median values of t(lag) of which I am aware, and it may be that Judge Massei simply misunderstood Dr. Lalli’s report or did not clearly understand the distinctions among the various measures of gastric emptying. A website at Colorado State University on the pathophysiology of the digestive system shows the differences among t(lag), t(1/2), and the time for complete emptying. These values are about 80, 150, and 220 minutes, respectively in this diagram.
A 2003 study by Chen et al. (J. Gastroenterology and Hepatology, 18, 41-46) determined a value of t(lag), namely 81.9 ± 17.4 minutes, with a range of 37.1 to 117.8 minutes. The authors described the test meal: “The egg [one yolk and two whites] was ingested with two slices of white bread coated with 7 g of margarine and 8 g of grape jelly, followed by 150mL water.” A paper on gastric emptying times (Hellmig et al., "Gastric emptying time of fluids and solids in healthy subjects determined by 13C breath tests: influence of age, sex and body mass index" Volume 21, Issue 12, pages 1832–1838, Journal of Gastroenterology and Hepatology, December 2006), was published in the Journal of Gastroenterology and Hepatology, which is peer-reviewed. Other articles cited this paper at least 25 times. These workers described their test meal: “After addition of 50 mL of low-fat milk, the egg was scrambled and fried in a pan. The solid test meal was completed by a piece of brown bread (50 g) and butter (20 g).” They showed that t(lag) for a solid meal did not follow a normal distribution. The median time was 82 minutes, with the 25% percentile at 66 min. and the 75% percentile at 102 min. Out of 82 subjects (Figure 1D), the longest value was 200 minutes, and the next longest was 170 minutes (each value corresponded to a single individual).
If one uses 6:30 as an estimate for when Meredith began to eat, then 9:50 (200 minutes after 6:30) is a working estimate of the outermost reasonable time at which Meredith was still alive. In fact, the meal may have started earlier than 6:30, given the testimony of Meredith’s friends. The problem for the prosecution does not get much better if one assumes that Meredith began her meal at 7:45 (when the desert was finished, according to Ms. Purton) and uses 200 minutes as the longest possible t(lag). This assumption puts the latest reasonable TOD at 10:55 PM. However, this TOD is far less likely than (for example) 9:05 PM, which is 80 minutes after 7:45. In other words, there is no possible time for Meredith to have consumed her last meal that favors Judge Massei’s TOD over a TOD between 9 and 10 PM.
Other indications of Meredith’s time of death
The Hellman-Zanetti report did not attempt to use stomach/duodenum physiology to ascertain the TOD. However, these judges did use other means to reach a similar conclusion. Meredith attempted to call her mother around 8:56 but was unsuccessful. Meredith called her mother once a day; therefore, it would be odd that she did not call back in the period in which she was supposed to have been alone in the prosecution’s scenario. Later there were two activities in close succession, namely an aborted call at 9:58 to Meredith’s answering machine and one at 10:00 PM to Meredith’s bank, but without the country code, neither of which is a complete call. Finally at 10:13 there is a GPRS internet connection for 9 seconds. The summary of Raffaele’s appeal document notes that the tower that handled this interaction can reach both the apartment and the location at which the phones were finally found. It is difficult to see why Meredith would have initiated any of these three later activities herself.
It is strange that Meredith did not try to call her mother after her attempt at 8:56 did not succeed. Nor did she call, text, or email anyone else after she arrived home, presumably close to 9 PM. She did not change into night garments or remove clothing from a washing machine. The Hellmann court put the TOD at 10:13 at the latest, and yet the evidence suggests that the TOD might have been earlier even without bringing in the physiology of gastric emptying.
The cell phone data suggest that Meredith died no later than 10:13 PM, as Judges Hellmann and Zanetti indicated. It is undisputed that there was activity on Raffaele’s computer at 9:08 PM, and the defense argued that there was activity at 9:26 and that the screensaver log files indicate additional activity. Even by itself, the lack of material in the duodenum strongly suggests that the time of death was likely to be earlier even than 10:13. Therefore, there was not enough time for Raffaele and Amanda supposedly to become very messed up from alcohol and/or drugs, to meet Rudy Guede, and to initiate a long series of actions that culminates in murder. It is likely that Meredith was attacked shortly after returning home, probably between 9 and 9:30.