Crime Scene Investigator Network Newsletter

Introduction

String reconstruction is an acceptable method for showing the suspected path of a bullet at a shooting scene. This method allows the investigators, members of the court, and the jury a way to visualize possible locations of the suspect or the victim in a shooting case. Stringing a shooting scene also shows the approximate flight path of the bullet relative to the rest of the scene. This, for example, may allow everyone to better determine the reliability of witnesses. It is helpful to emphasize that the exact flight path is nearly impossible to determine but that a very close approximation of the point of origin can be reliably determined.

The reconstruction of a shooting scene by the string method can sometimes pose several problems for investigators. Weather conditions at an outdoor scene, such as gusting wind, can make stringing the scene impractical, if not impossible. Terrain with trees or bushes that partially block the trajectory path, or low spots that place the path of the string out of reach, are also considerations. The sagging of the string becomes an issue as the investigator extends the analysis away from the point of impact of the projectile. Also, photographs of the reconstruction that accurately portray the angles and their relationships to each other can sometimes be difficult to obtain. This is usually not discovered until after the scene has been released.

An investigator who understands basic trigonometry can overcome these issues by calculating the flight path of the projectile using trigonometry. Unlike the string method, the trigonometric method is not inherently prone to error by interference of physical conditions at the scene. It can be used in conjunction with string data and scale drawings to help support conclusions. The trigonometric method allows the investigator to more easily determine the location of the trajectory at any point along the flight path. The measured data is also much more easily included in computer-generated scale drawings with programs such as AutoCad. The use of such programs is recommended because the dimensioning tools included can illustrate and compare trajectory paths from several bullets to determine their relative distances from each other. This is impractical and at times nearly impossible to perform with the traditional string method.

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