The Casey Anthony Murder Trial: ADD Analysis

I have done an analysis on the ADD estimate provided in the report released on analysis of decomposition gases present in KC's trunk. In the report the maximum estimated ADD (Accumulated Degree-days) was estimated at 2.6 days (62.4 hours) based on a constant temperature of 35C (95F). However, the days from June 16th onward were slightly cooler than this and so I wanted to see how this would change the calendar days that Caylee's body could have been in the trunk.

Assumptions:

I have assumed that Caylee's body was placed in the trunk some where around 4:00 p.m. on 06/16. This corresponds with the time that KC's cell phone activity went into rapid-fire mode.

I have assumed that Caylee's body remained in the trunk until it was permanently removed. (i.e. not moved out and then back in)

I have assumed the temperature in the trunk to be that of the ambient outside temperature and have not added or substracted any convective/radiant heat additions or losses. I have also assumed no lag between change in temperature within the trunk relative to change in outside temperature.

I have assumed that at no time over the period analyzed the temperature fell below the threshold temperature for decomposition to continue (i.e. it was always warm enough for the body to continuously decompose.)

Methodology:

I used historical data for the days analyzed from Weather Underground.

I averaged the temperature for each hour beginning at 3:53 pm on 06/16/08.

I calculated ADD per hour to refine the analysis since the important question comes down to the hour, versus just half days or full days.

Since it is assumed the threshold temperature was always met and exceeded, the difference in the rate of decomposition between the actual average temperature of a given hour and that hour at 35 C will reduce to the ratio of T(actual)/35.

The new temperature-adjusted decomposition rate was then subtracted from the total maximum ADD listed in the report (62.4 hours) until that total was reached.

It is noted that the report states that the ADD may have very well been less than 2.6 (62.4 hours).

Results:

The following graphics split the spreadsheet I created into three sections. The 2.6 days at 95F (35C) is noted in the third section, as well as the equivalent ADD for the actual temperatures. In addition, it is noted that 1:30 p.m. 06/19/08 falls within the envelope of the original ADD at the higher constant temperature and the new ADD using actual temperatures.

Conclusion:

BB was unable to remember if the shovel incident occurred on 06/18/08 or 06/19/08, but was fairly certain that it was around 1:30 p.m. Based on this analysis of an adjusted actual time period to arrive at the same level of decomposition as estimated in the official report, it appears that the shovel incident may have occurred at 1:30 p.m. on 06/19/08. Based on this information one could assume that in some relatively short timeframe after the shovel incident, the body was removed from the trunk permanently.

Awesone. You should be on Nancy Grace. All that work and detail would give her a spontaneous orgrasm.