Mall Gita, Eckl Mona, Sinicina Inga, Peschel Oliver, Hubig Michael
Institute of Legal Medicine, Ludwig-Maximilians-University Munich, Frauenlobstrasse 7a, 80337, München, Germany.
Int J Legal Med. 2005 Jul;119(4):185-94. doi: 10.1007/s00414-004-0461-4. Epub 2004 Oct 6.
The temperature-oriented death time determination is based on mathematical model curves of postmortem rectal cooling. All mathematical models require knowledge of the environmental conditions. In medico-legal practice homicide is sometimes not immediately suspected at the death scene but afterwards during external examination of the body. The environmental temperature at the death scene remains unknown or can only be roughly reconstructed. In such cases the question arises whether it is possible to estimate the time since death from rectal temperature data alone recorded over a longer time span. The present study theoretically deduces formulae which are independent of the initial and environmental temperatures and thus proves that the information needed for death time estimation is contained in the rectal temperature data. Since the environmental temperature at the death scene may differ from that during the temperature recording, an additional factor has to be used. This is that the body core is thermally well isolated from the environment and that the rectal temperature decrease after a sudden change of environmental temperature will continue for some time at a rate similar to that before the sudden change. The present study further provides a curve-fitting procedure for such scenarios. The procedure was tested in rectal cooling data of from 35 corpses using the most commonly applied model of Henssge. In all cases the time of death was exactly known. After admission to the medico-legal institute the bodies were kept at a constant environmental temperature for 12-36 h and the rectal temperatures were recorded continuously. The curve-fitting procedure led to valid estimates of the time since death in all experiments despite the unknown environmental conditions before admission to the institute. The estimation bias was investigated statistically. The 95% confidence intervals amounted to +/-4 h, which seems reasonable compared to the 95% confidence intervals of the Henssge model with known environmental temperature. The presented method may be of use for determining the time since death even in cases in which the environmental temperature and rectal temperature at the death scene have unintentionally not been recorded.
基于尸体直肠温度下降的数学模型曲线来确定以温度为导向的死亡时间。所有数学模型都需要了解环境条件。在法医实践中，有时在死亡现场并未立即怀疑是他杀，而是在尸体外部检查时才发现。死亡现场的环境温度仍然未知，或者只能大致重建。在这种情况下，就会出现一个问题，即是否有可能仅根据在较长时间跨度内记录的直肠温度数据来估计死亡时间。本研究从理论上推导了与初始温度和环境温度无关的公式，从而证明了死亡时间估计所需的信息包含在直肠温度数据中。由于死亡现场的环境温度可能与温度记录期间的环境温度不同，因此必须使用一个额外的因素。即身体核心与环境热隔离良好，环境温度突然变化后直肠温度下降将以与突然变化前相似的速率持续一段时间。本研究还为这种情况提供了一种曲线拟合程序。该程序在35具尸体的直肠温度冷却数据中使用最常用的亨斯格模型进行了测试。在所有情况下，死亡时间都是确切已知的。尸体被送往法医机构后，在恒定的环境温度下保存12 - 36小时，并持续记录直肠温度。尽管在进入机构之前环境条件未知，但曲线拟合程序在所有实验中都得出了有效的死亡时间估计。对估计偏差进行了统计调查。95%的置信区间为±4小时，与已知环境温度的亨斯格模型的95%置信区间相比似乎是合理的。即使在死亡现场的环境温度和直肠温度无意中未被记录的情况下，所提出的方法也可能有助于确定死亡时间。
