NCJ Number
198080
Journal
Journal of Forensic Sciences Volume: 47 Issue: 6 Dated: November 2002 Pages: 1309-1318
Editor(s)
Michael A. Peat Ph.D.
Date Published
November 2002
Length
10 pages
Annotation
In this report, the authors used one-videotape and three photographs to perform a new study and analyze recorded sound to determine gunshot location and attribute authorship in a fatal shooting incident during labor riots in Argentina.
Abstract
During a repression of labor riots in Argentina in April 1997, a 24-year old woman was fatally shot. The incident was videotaped, as well as photographs taken of the victim by reporters. During the trial, repeated studies of the videotape and photographs gave no clear indication on who fired the shots and killed the young woman. The judge in the case requested the authors of this report to perform a new study of the material (one-videotape and three photographs) from their point of view as physicists and analyze recorded sound to attribute authorship in shooting death incident. To investigate the acoustics at the scene they recorded detonations at four selected locations on the isolated bridge where the incident occurred. To find the locations of the objects that produced echoes, they superimposed the ellipses corresponding to the most nitid echoes for four detonations. The isolated bridge of the crime scene resulted in a poor acoustic signature with few distinctive features. Once the objects producing the echoes were identified, fluctuations in their times of arrival were noticed. Two methods were used to search for the location of each shot: (1) computing the matching between one given list of delays of echoes and those that would be generated by the posts and walls identified by a shot produced on a given position and (2) the crossing of hyperbolas. The methods were tested by applying them to experimental detonations. When the methods were applied to the real shots, 11 out of the 17 could be located, with at least 7 of the 10 echoes accounted for. Results indicate that all the shots located came from the police ranks. Analysis of the videotape proved that the victim started falling roughly at the time of the ninth shot. In addition, the suspect who had been charged on the basis of a previous study fired none of the 11 located shots, and specifically did not fire the eighth shot. In conclusion, even though it cannot clearly be identified as to who fired the fatal shot the acoustic analysis exculpated one suspect and circumscribed the responsibility to one man within a small, well-localized group. Future research recommends improvement in the areas of echo identification and combining the isolated echoes into a coherent pattern. Figures and references