Time since death nomographs implementing the nomogram, body weight adjusted correction factors, metric and imperial measurements

Stefan Potente, Mattias Kettner, Takaki Ishikawa

The concept of nomography was developed around 1880 as a means to compute formulas graphically. Regular use has decreased over time in most fields, mainly owing to progress in electronic computation devices. In forensic pathology, nomography is still used in the so-called "nomogram method" for the estimation of time since death. It is the graphical representation of the formula by Marshall and Hoare with the parameters of Henssge. Here, two nomograms exist (for ambient temperatures below and above 23 °C, no imperial measurements). Rounding for body weight input and result reading introduces errors. In addition, correction factors, applied to body weight, allow to adapt for certain conditions on the crime scene and are essential to the method. They are not directly integrated into the nomograms but must be applied in advance. A formula, scaling correction factors for different body weights, was later added by Henssge, along with a simplified table for case work. In this publication, we present newly designed time since death nomographs as representations of Henssge's parameters with the addition of both metric and imperial measurements, integration of weight adjusted scaling of correction factors, and a geometrically consistent framework for body weight and result reading, which eliminates some rounding steps and reduces the overall rounding-related estimation errors.