taser distance determination
yu ran (danny) zhou
Purpose: The purpose of the research was to examine whether distance determination could be accurately established for TASERs (models X26P, TASER 7, and X2) using TASER-to-target distances, probe launch angles, and probe spread. In cases involving the use of TASERs, if testimonies and witness accounts are unclear or inconsistent in describing the relative positions of involved individuals, then TASER distance determination could help contextualize the scene.
Methodology: The total sample size was n=72. Each of the 4 probe cartridge types were fired at 3 different distances from large, vertical, cardboard targets for 6 repetitions. The TASER-to-target distances chosen for each cartridge type were the most appropriate for the range capability of each model, optimizing data collection for the most relevant results. X2 cartridges were launched from 3m, 6m, and 8m away from the target. TASER7 Close Quarters cartridges were launched from 3m, 4.5m, and 6mfrom the target. TASER 7 Standoff cartridges were launched from 3m, 6m, and 8m from the target. X26Pcartridges were launched from2m, 4m, and 6m from the target. TASERs were held by a Ransom Rest to maintain consistency and minimize human error. Puncture holes created by the probes upon contact with targets were labelled, and the distances between each pair were measured for probe spread. For each cartridge type, the probe spread was plotted against TASER-to-target distance, generating linear trendlines and standard deviation for the average value at each distance. The trendline equations were then used to perform distance determination calculations for comparison against blind test results. Blind testing comprised of 5 repetitions for each of the 4 cartridge types, for a total of20 tests
Results: The graphs demonstrated that rates of probe spread increase were proportional to probe launch angles. TASER 7 Standoff (3.5olaunch angle) had an average probe spread rate of 7.6cm / TASER-to-target distance (m).X2 (7olaunchangle)had an average probe spread rate of12cm / TASER-to-target distance(m).X26P (8olaunch angle) had an average probe spread rate of 14.7cm / TASER-to-target distance (m).TASER 7 Close Quarters (12olaunch angle) had an average probe spread rate of23.5cm / TASER-to-target distance (m).Results also showed greater standard deviation values at greater TASER-to-target distances, consistent with the expectation that accuracy would decrease while further from the target. When comparing equation-based distance calculation values against the blind test results, it was found that estimated distances were less than actual distances across all cartridge types.Onaverage,X2 distance calculations were around 8.7cm less than the actual distance. TASER 7 Close Quarters distance calculations were around 15.8cm less than the actual distance. TASER 7 Standoff distance calculations were around 23.2cm less than the actual distance. X26P distance calculations were around 28.1cm less than the actual distance. Overall, it was observed that all calculated distances estimated the target to be closer to the TASER at the time of launch than it was in actuality. However, the average error margin between calculations and actual distances were all within 30 cm, with the most accurate calculation being approximately 8.7cm closer than the actual distance.
Conclusions: There is a linear relationship between probe spread and TASER-to-target distances for the X2, TASER 7 Close Quarters, TASER 7 Standoff, and X26P cartridge types. The rate of probe spread, launch angles, and observed probe spread on targets were all variables that effectively culminated in distance determine. We expect our findings will help establish a reliable method of distance determination for TASERs, and perhaps with a larger sample size, generate calculation models with more accuracy and lower error margins. TASER distance determination has the potential to provide support in contextualizing crime scene reconstruction with further research. By providing distance estimations alongside validated error margins, it would be possible to induce how far apart individuals were at the time a TASER was fired, within the calculated window of error.