The Human Factor in Crime Scene Measurement Accuracy: A Comparison of Four Measuring Devices and Three Crime Scenes

Abstract

Measurements in crime scene sketches need to be accurate, as they are used in court and to recreate a scene. The accuracy of devices used in crime scene measurements has been studied; however, there is little research on the amount of measurement variability introduced by the user. This research investigated the average human error along with the accuracy of three different measuring devices. Three mock crime scenes were set up – 2 indoor scenes (with and without furniture) and 1 outdoor scene. Twentyone volunteers were used to measure 10 predetermined measurements in each of the three scenes using 3 different measuring devices. Volunteers had no previous experience measuring crime scenes and were provided with the same instructions. Each volunteer measured all three scenes. Measurements were taken in the same sequence first using a class 2 measuring tape (a TR Industrial 88016 FX Measuring Wheel™ was used on the outdoor scene), then Bosch GLM 35™ and Leica DISTO 810™ electronic measuring devices. The data from each measurement was averaged for each measuring device within a scene and compared. Angles and the presence of furniture increased measurement variability in indoor scenes. In the outdoor scene, measurements that were not taken along walls (e.g. from one marker to another) had significant variability. The measuring device used does not appear to have a significant impact on measurement variability when scenes are “easy” to measure but may make a difference in large scenes or scenes with angles or obstacles, particularly in novice investigators.