Distribution of GSR particles in the surroundingsof shooting pistol

Lubor Fojtasek, Jitka Vacınova, Pavel Kolar*, Marek KotrlyInstitute of Criminalistics Prague, P.O. Box 62/KUP, Strojnicka 27, 170 89 Prague 7, Czech Republic

Received 18 January 2002; received in revised form 22 August 2002; accepted 2 September 2002

Abstract

Several series of experiments were performed to study the distribution of GSR particles in seven directions in the surroundings

of shooting firearm (pistol CZ 85 caliber 9 mm Luger). External and internal conditions and two different primer types were

used for the shooting experiments. The results showed that maximum number of GSR particles could be found in the right

front quadrant at a distance of 2–4 m with respect to the shooting firearm position and shooting direction. GSR particles were

even found in distance 10 m from shooting firearm. A significant influence of climatic conditions on GSR distribution was

confirmed.

# 2003 Elsevier Science Ireland Ltd. All rights reserved.

Keywords: Forensic science; Criminalistics; Gunshot residues; Particle distribution

1. Introduction

The investigation of gunshot residue (GSR) particles has

extensive significance in forensic examination of cases

involving suspected use of firearms. The number of detected

particles is one of the crucial factors influencing the deter-

mination of a probable contact with shooting gun. In prin-

ciple this number is affected by the physical activity of a

subject after the shooting incident [1,2], by the character-

istics of human skin on hands [1], by the method and quality

of particles recovery [3,4]and last but not least by the

distance from the shooting firearm.

While the persistence of gunshot residue particles on hands

was extensively reported [1,2,4–6], there are sporadic studies

of transfer of GSR in the surroundings of the shooter. In one of

them Andrasko and Petterson [3] presented a shooting experi-

ment where one person was standing on the right side of the

shooter and another person behind him. Then they examined

the contamination of clothing by GSR particles of these

persons presented during firing and walking immediately

after the discharge through the particle cloud.

The most reliable method combining the examination of

morphology and the chemical composition of GSR particles

is scanning electron microscopy equipped with an energy

dispersive X-ray analyser (SEM/EDX) [2,5,7]. Recovery of

gunshot residues from hands, face, hair and clothing is

mostly done by adhesive tapes, with hair combing and air

filtration systems used less.

The examination of GSR with the aim of differentiating

the possible shooter from other persons present is often

requested by investigators and the police when firearms are

used in criminal activity. The lack of information on dis-

tribution of gunshot residue particles in surroundings of the

shooter and frequent discussion of that problem at the courts

has led the authors to experiment with the aim of estimating

the maximum radius of GSR in the surroundings of the

shooter and mapping their quantity and distribution.

2. Experimental

The first series of shooting experiments were carried out

in a closed environment having an area of approximately

660 m2 and height of 7 m. A CZ 85, caliber 9 mm Luger was

employed with commonly used ammunition 9 mm Luger

Sellier & Bellot. The arm and ammunition were chosen on

Forensic Science International 132 (2003) 99–105

* Corresponding author. Tel.: þ420-2-61424349;

fax: þ420-2-61424323.

E-mail address: kolarkup@mvcr.cz (P. Kolar).

0379-0738/03/$ – see front matter # 2003 Elsevier Science Ireland Ltd. All rights reserved.

doi:10.1016/S0379-0738(03)00018-5

the basis of statistics monitoring the occurrence of arms and

ammunition in casework in Czech Republic.

To study the spatial GSR distribution seven radial direc-

tions originating from the supposed gun position at the

moment of discharge were selected. In each direction several

accumulating targets with the size of 25 cm � 25 cm with a

smooth surface were distributed as shown in the Fig. 1. In

order to prevent any possible contamination from the floor,

the accumulating targets were placed on supports at the

height of 10 cm from the floor.

In order to simulate GSR particle distribution in real

external conditions a second independent series of experi-

ments was carried out. The experiments were conducted in a

half-open hangar with the dimensions of 15 m � 50 m and

the height of 8 m at an abandoned military airport. The

shooter was positioned with his right side towards the open

side of the hangar, 15 m long. The experimental set-up was

similar to previous series of experiments (Fig. 1). During the

experiments the wind reached a velocity of approximately

5 m per second.

To verify the reproducibility of the shooting experiments

in a closed environment a third independent series of experi-

ments was later carried out in a garage 8 m long, 4 m wide

and 3 m high. During the experiments the same gun CZ 85

caliber 9 mm Luger was employed, but ammunition 9 mm

Luger Sellier & Bellot from different production runs was

used. Because of limited space in the garage the accumulat-

ing targets were distributed only in the direction of shooting.

Given the results obtained from the first series of experi-

ments, one additional target was placed in the position of

supposed maximum occurrence of GSR particles (at 3 m in

the direction 458 right from the shooting direction).

In the course of the all experiments the standing shooter

fired off one round with his right hand. During 30 min thought

to be necessary for complete condensation of all GSR particles

all persons assisting with measurements stayed immobile.

The accumulating targets were then carefully sampled with

minimal movement using double-side adhesive carbon tapes

(Christine Gropl for SEM) fixed on aluminum stubs. All tar-

gets were sampled in a standard way by taping their surfaces

100 times in distinct places. In order to obtain the maximum

data from the experiment each was repeated three times.

All sites selected for the shooting experiments were tested

(before the experiments) for possible contamination by GSR

particles. The analysis of the blank samples for the presence

of GSR particles was negative. The air temperature and

Fig. 1. Scheme of the experimental set-up.

100 L. Fojtasek et al. / Forensic Science International 132 (2003) 99–105

humidity were monitored during all series of experiments.

The temperature varied among the different experiments

from 19 to 21 8C and humidity varied between 55 and 80%.

3. Results and discussion

All samples were examined and analysed manually using

the scanning electron microscope CamScan 2 equipped with

energy-dispersive X-ray analyser LINK ISIS 300. During

the sample analysis only the unique GSR particles [8] were

taken into account. In our case the 9 mm Luger Sellier &

Bellot ammunitions from different production runs were

used, so we were only interested in the GSR particles with

the elemental compositions of Pb, Sn, Ba, Si, Ca and Pb, Sn,

Sb, Ba respectively. The mean values of detected GSR

particles from the first series of three experiments in seven

selected directions are summarised in the Table 1.

As seen from the Table 1, the GSR particles can be found

even in the distance of 10 m from the shooting gun position.

The maximum quantity (several thousands) was detected in

the direction 458 right from the shooting direction, a high

quantity of GSR particles (several hundreds) was also found

in the direction of shooting and on the right side of the

shooter. The distribution of GSR particles in these three

directions is compared in the Fig. 2.

The overall spatial distribution of GSR particles in the

surroundings of the shooter, that was calculated using the

values from seven selected directions is shown in the Fig. 3.

During the evaluation of the experiments the results

obtained from closed and open environments were com-

pared. As expected the results of experiments in an open

environment demonstrated the significant influence of cli-

matic conditions on the quantity of detected GSR particles.

Even though the maximum quantity of GSR particles

was detected in the direction 458 right from the shooting

direction as in the first series of experiments in the closed

environment, their total number was ten times lower. The

distribution of GSR particles in the direction 458 right from

the shooting direction measured in internal and external

conditions is compared in the Fig. 4.

In the course of data treatment from the third series of

experiments in the garage the examination was focused not

only on a total GSR particle distribution in the direction of

shooting but also on the distribution of GSR particles as a

function of their size. The results of the particle analysis

show that the curve of total GSR particle distribution in the

shooting direction has the similar behaviour as curves

obtained from previous experiments. Nevertheless the max-

imum quantity of GSR particles in this direction reaches

several thousands of particles and on one target placed at 3 m

in the direction 458 right from the direction of shooting only

several hundreds of particles were found. These results

indicate the strong dependence of GSR particles distribution

on ammunition used. The distribution of GSR particles in the

direction of shooting obtained from the 9 mm Luger Sellier

& Bellot cartridges with different primer compositions

measured in two independent series of experiments in

internal conditions are compared in the Fig. 5.

The results from the data treatment from the third series of

experiments showed that the majority of particles had a size

less then 3 mm. The distribution of GSR particles as a

function of their size and the distance is summarised in

the Fig. 6.

The results of the study have indicated the spatial dis-

tribution of GSR particles in the surroundings of a shooting

pistol. Generally in the case of shooting with a short arm

(particularly with a pistol) the maximum quantity of GSR

particles is located in the right front quadrant with respect to

the shooting arm position and shooting direction. These

results are in a good concordance with the expected direction

of escaping gunshot residues from the pistols. The maximum

Table 1

Mean values of GSR particle quantities in seven selected directions in the surroundings of the shooter

Distance from

shooting gun (m)

Number of detected particles in particular direction from the shooter

Shooting direction Right Left 458 right 458 left Back 458 right Back 458 left

0.5 105 85 58 125 75 – –

1 320 265 25 1450 228 100 46

1.5 410 570 20 1920 142 – –

2 520 670 28 2080 102 48 35

3 580 560 34 2670 31 32 23

4 550 880 11 3020 15 7 3

5 335 490 10 640 13 0 0

6 20 460 3 225 5 – –

7 20 101 0 53 0 – –

8 6 22 0 20 0 – –

9 1 5 – 18 – – –

10 0 0 – 6 – – –

11 0 0 – 0 – – –

L. Fojtasek et al. / Forensic Science International 132 (2003) 99–105 101

Fig. 3. Overall spatial distribution of GSR particles in the surroundings of the shooter.

Fig. 2. Distribution of GSR particles in the direction 458 right from the shooting direction, in the direction of shooting and on the right side of

the shooter. The error bars of 15 percent of experimental values correspond to the precision of measurement.

102 L. Fojtasek et al. / Forensic Science International 132 (2003) 99–105

Fig. 4. The distributions of GSR particles in the direction 458 right from the shooting direction measured in internal and external conditions.

Fig. 5. The distributions of GSR particles from the 9 mm Luger Sellier & Bellot cartridges with different primer compositions in the direction

of shooting measured in internal conditions.

L. Fojtasek et al. / Forensic Science International 132 (2003) 99–105 103

number of GSR particles (several thousands) was found

approximately 3 m from the shooting arm position in a

direction 458 right from the direction of shooting. The

maximum quantity of detected GSR particles decreases con-

siderably to several hundreds in the case of shooting experi-

ments carried out in external conditions. As demonstrated

by the results from experiments in internal conditions some

GSR particles were even found at a distance of 10 meters far

from the shooting arm position. The results obtained from

experiments carried out in external conditions, however,

indicate the total number of GSR particles is drastically

influenced by climatic conditions and practically no particle

was found further then 6 m from the shooting arm position.

With respect to the very high concentration of GSR

particles in the distance of 2–4 m from the gun position it

seems to be practically impossible to distinguish between the

shooter and another person present in the moment of the

discharge. Andrasko and Petterson [3] presented in their

paper shooting experiments aimed at determination of con-

tamination by GSR particles. During the experiments two

persons were standing on the right side of the shooter and

behind him. Thirty seconds after the sequence of four shots

with a 0.357 Magnum revolver the persons passed through

the area ahead of the shooter and their coats were vacuumed

and examined for the presence of GSR. The authors [3]

interpreted the contamination of clothing by GSR rather as

result of walking through the particle cloud than staying

close to the shooter. Alternatively the relatively low number

of GSR particles found on the clothing could indicate

different spatial distribution of GSR particles from a revol-

ver or their incomplete condensation.

The results of third series of experiments conducted

in a closed environment indicate the same behaviour of

characteristics of GSR particle distribution. Nevertheless an

interchange of a quantity of GSR particles was observed in

two monitored directions (direction of shooting and direc-

tion of 458 on the right side from the shooting direction).

This variation in GSR particle distribution can be caused by

ammunition with distinct primers from different production

runs used in two independent series of experiments. The

results of experiments did not indicate any observable

difference in distribution of particles with different sizes

as a function of distance but showed that majority of GSR

particles has a size less then 3 mm.

4. Conclusion

This study was initiated by several ‘‘frequently asked

questions’’ that we encounter during casework investiga-

tions. The questions concern, above all, the possible quantity

of detected GSR particles, their distribution and the possi-

bility of distinction between the shooter and another person.

By means of several series of model shooting experiments

we wanted to resolve some of these real problems that we

encounter during our everyday routine operation.

The results of reported study indicate that in the case of a

short arm used in closed environments the GSR particles can

Fig. 6. The distributions of GSR particles in the direction of shooting as a function of their size.

104 L. Fojtasek et al. / Forensic Science International 132 (2003) 99–105

be detected over longer distances (even at 10 m) than was

supposed with regard to previous estimations (approxi-

mately 6 m). Additionally the maximum quantity of GSR

particles was not found in the immediate vicinity of the

shooter but in the distance of several meters from the

shooting arm position. Presented results show GSR particle

distribution in close vicinity to the floor 30 min after the

discharge. Similar distribution probably with less amount of

GSR particles may be expected in height to 1 m from the

floor. In real cases it could be difficult to distinguish between

the shooter and other persons present during or immediately

after the discharge One can argue that the quantity of GSR

particles found on the hands could be the decisive factor for

the identification of the shooter. However, several previous

studies focused on this problem of the quantity of GSR

particles on the hands of supposed shooter found that the

number depends on different factors that can strongly influ-

ence the resulting detected number. The results obtained

from the shooting experiments carried out in external con-

ditions show that valuable evidence from the presence of

GSR particles can only be obtained in close proximity of the

supposed shooting arm position. The conclusions of the

presented study can be potentially used for evidence recov-

ery in real case investigations.

Acknowledgements

This study was supported by a grant no. 19982000004

from the Ministry of the Interior of the Czech Republic.

We would like to thank to Tomas Kmjec and other collea-

gues from the department of ballistics of Institute of Crim-

inalistics Prague for their help with shooting experiments

and helpful discussions during the preparation of this paper.

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