Estimation of Shooting Distance: Birdshot to the Head

In criminal cases where shootings take place it is often necessary to estimate the shooting distance. Usually garments of the victim are chemically treated for this purpose. In cases where the victim was shot on the skin, skin simulants [1] are used to assess the distance, after thoroughly examining the gunshot wound.  Test shots with the alleged weapon and ammunition are performed. In cases where a shotgun with buck shots [2] are used, determining the distance is also based on the pellet distribution patterns [3-7], in combination with chemical testing [8] which has proven to be an added value in the quest to estimate the most probable distance.

In an attempted murder case, a woman was shot to the back of her head [Figure 1] with a 9 mm Flobert birdshot [Figures 2-6], at an approximate distance of 1,5 m between her head and the muzzle of the rifle [Figure 7] according to her statement. Three pellets penetrated her scalp and two more were found being clustered in her hair, which she wore in a pony tail [Figure 8]. Shooter and victim are of about the same stature. The investigating judge instructed the medical examiner to determine the exact locations of the entrance wounds and the projectiles under the skin. The ballistic expert was then asked to perform reference shots using the alleged firearm and ammunition that were confiscated at the suspects residence in order to compare the pellet distribution patterns. To assess pellet pattern distribution as a function of shooting distance, the Equivalent Circle Diameter method was used. In the shooting range, a dummy was equipped with a skin simulant, a wig and an unused sweater, so the crime scene situation was reconstructed as closely as possible. Additionally, IR photography and the Sodium Rhodizonate test were performed to visualize the gunshot residues on the victims clothing and skin simulants for the distance determination on chemo graphical basis. The ammunition used in the crime Fiocchi birdshot  (shot number 6) contains 59 pellets, and since only 5 pellets were retrieved, the distribution pattern on which to evaluate the shooting distance is only partial.

The medical examination of the gunshot wound revealed the position of the 3 pellets in the scalp [Figure 9] but the exact position of the entrance wounds could not be established by the medical examiner, which made it impossible to determine the shooting direction. However the shooting distance can be estimated, by performing reference shots, and comparing them to the pellet distribution patterns, using the “equivalent circle diameter method” and visual comparation.

Equivalent circle diameter method 

A series of test shots were performed using the alleged weapon and ammunition of the same brand and type as was used in the crime on paper targets, at shooting distances 0,5 – 1 – 1,5 – 2 – 3 – 4 meters. Polygons [Figure 10] were drawn around the outermost pellets, the equivalent circle diameters were determined and put in a diagram versus the distance. 

Skin simulant 

Skin simulant targets, being a piece of leather, are attached to cardboard and test shots were performed using the alleged weapon and similar ammunition as used at the crime, at the same distances as above to determine the skin perforation characteristics of the pellets [Figure 11] as a preliminary test. At 0,5 m all pellets perforate the simulant in a small bundle. 

Simulation of realistic conditions 

The conditions of the shooting incident were simulated to mimic realistic circumstances using a dummy, clothed with an unused fleece vest [Figure 12]. The Styrofoam head was covered with the skin simulant [Figure 13], and an unused wig with long hair in a pony tail was placed over it [Figure 14], in the same way that the victim wore her hair [Figure 8] when she got shot. The alleged weapon and ammunition were used to perform the test shots. The shotgun was mounted into a bench [Figure 15], and was fired from a distance. The shooting distances that were deemed most probable based on the preliminary test being 1 m and 1,5 m were tested first. The absorbing effect of the wig became immediately apparent and due to lack of perforation of the skin simulant, which prompted us to test additional distances of 0,5 and 0,75 m. 

Chemometric analysis 

• Examination of the victims clothing 

The clothing of the victim [Figure 16] is examined under IR light using a Crime-Lite^®Auto Camera of Foster&Freeman, resulting in an image where the gunshot residue particles are visualized as black specks against a whiter background [Figure 17]. Subsequently, the fleece vest is treated with the optimized Sodium Rhodizonate method culminating in a pink distribution pattern [Figure 18] due to the color reaction of the lead particles with the azo dye.

• Analysis of the skin simulants 

The leather targets [Figure 11] of the test shootings are also treated with the optimized Sodium Rhodizonate method, producing a series of patterns for the different distances [Figures 19&20], giving an indication to the amount of gunshot residue that Fiocchi 9 mm Flobert shot 6 could produce when it’s fired in the alleged weapon. 

• Analysis of the reference clothing 

Finally the reference vests that were shot at distances of 1 and 1,5 m have been treated with the same chemo graphic test, to study the influence of the hair simulant (wig) on the retention of possible gunshot residue deposit on the garment.

 Figure 1: Gunshot wound victim. 

Figure 2: Birdshot 9 mm Flobert Hail n°6. 

Figure 3: Cartridge. 

Figure 4: Headstamp. 

Figure 5: Wadding. 

Figure 6: Pellets. 

Figure 7: Single shot shotgun 9 mm. 

Figure 8: Pony tail victim.

 Figure 9: Gunshotwound measured by medical examiner. 

Figure 10: Polygon for distance 1,5 m. 

Figure 11: Skin simulant distance 1,5 m. 

Figure 12: Reference fleece vest.

 Figure 13: Styrofoam head with skin simulant. 

Figure 14: Dummy with hair simulant.

 Figure 15: Rifle fixed in bench. 

Figure 16: Garment victim. 

Figure 17: IR photograph of garment victim. 

Figure 18: Rhodizonate test on hood of vest of victim in mirror. 

Figure 19: Rhodizonate test on skin simulant at distance 0,5 m. 

Figure 20: Rhodizonate test on skin simulant at distance 1,0 m. 

From the Equivalent Circle Diameter method shooting distances of 0,75 m and 1,5 m result in a pellet distribution pattern with a diameter of respectively 4,5 cm and 7 cm. The locations of the tree pellets that were lodged under the victims scalp were determined by the medical examiner at distances varying from 2,2 cm to 0,7 cm.

The skin simulants that were shot at 1 and 1,5 m were perforated by the shot bundle but also show some pellets perforating in the periphery. The skin simulants shot at 2 and 4 m distance have no perforation at all, while at 3 m 2 pellets perforated the target. 

The dummy, with skin simulant and wig, shot at 1,5 and 1 m, showed no perforation at all of the skin simulant, whereas at 0,5 m the pellets perforated in a bundle, and at 0,75 m the perforation was very limited by 1 single pellet [Figure 21]. A possible explanation for the diminishing effect of the perforation might be the net based structure of the wig, opposed to real hair.

 Figure 21: Skin simulant from dummy wearing a wig shot at distance 0,75 m. 

The result of the color test on the victims clothing is a large very dense pattern [Figure 18], suggesting a shooting in close proximity. 

Comparing the pattern of the victims clothing to the series of test shots on the leather targets after treatment is a means of estimating the probable shooting distance. In this case the distance seems to approach 0.75 m right in between the 0,5 and 1 m. The absorbing effect of the hair cannot be evaluated at this point, since it covered partially the garment at the moment of discharge. 

Two reference vests were shot at distances of 1 and 1,5 m to evaluate the buffering effect of the hair simulant on the chromophoric test. When the results showed indeed an enormous difference in amount of GSR compared to the victims vest, probably because the shooting angle was not completely identical, referring to the victims statement that she quickly turned around right before the impact, and this shooting angle hasn’t been tested to verify due to lack of the exact positions of the entrance wounds which could not be determined by the medical examiner.

Only a frontal shot was evaluated in this case study, due to lack of information the close angular shot could not be tested. The absorbing effect of hair and skin has been demonstrated, and the estimated distance fits closest to 0,75 m taking an uncertainty of 1 m into account because the effects of the net structure of the wig is not known compared to natural hair, giving a range up to 1,75 m most probable, and in confirmation of the victims statement declaring a distance of 1,5 m.

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