Journal of Radioanalytlcal Chemistry, Iiol. 15 (1973) 51--5R GUNSHOT RESIDUES ON PARAFFIN DROPS INSTRUMENTAL ACTIVATION ASSAY OF ANTIMONY, BARIUM AND COPPER G. BORRA,* A. BRANDONE,** G. DE BERNARDI,* A. FORNARI,* E. ORVINI,** M. A. ROLLIER** *lstituto di Medicina Letlale e delle .4ssicurazioni **Centro dl Radiochimica e Analysi per Attivazionc dei CNR presso lstituto di Chimica Generale, Universitd di Pavia, 27100 Pavia (Italy)
In an attempt to facilitate the removal of gunpowder residues from the skin, a simplified method has been tested as compared to the commonly used one of brushing with liquid paraffin. The removing material is still paraffin, but it is dropped from a lighted paraffin candle onto "..he first interdigital space of the hand. Maps were constructed for gunpowder residues on hands after pistol fixing and the first interdigital space was found to be the most sigrtifieant. Analysis of paraffin "blanks" from candles showed them to be free from antimony, barium and copper. Many sampies were examined from the left and the right hands of individuals who had or had not fired a pistol. The results clearly show that from the oontezat of Sb, primarily, and also of Ba, it is possible to identify the person who fired the pistol. Due to the random distribution of copper coming from the skin, this element appears not to be meaningful for the identification of pistol fixers, some practical cases of suicides and shootings ate reported.
Introduction Prerequisites
of a detection
method
The detection of gunpowder residues on the hands of a person is undoubtedly o f great importance in c r i m i n a l cases provided (a) the detection method is reliable, (b) the police personnel are familiar with the method and:its potential and (c) this type of evidence is accepted for introduction in court. Neutron activation analysis f (NAA) seems to have all the above prerequisities and is be,coming more widely used, especially in the USA by the Internal Revenue Service 1 a~d in Canada by K r i s h n a n . 2 The NAA method has helped to make obsolete the "paraffin" test which is no longer or rarely used. The paraffin cast technique though is used as an effective way of removing the gunshot residue components containing barium, antimony and copper in the submi3". Radloanal. Chem. 15 (1973)
4*
51
G, BORRA et al. : GUNSHOT RESIDUES
crogram range, but in this method of residue removal the paraffin simply acts as a mechanical collector of the residue components which may be present. These are assayed by neutron activation analysis without removing them from the paraffin on which they are collected if purely imtmmental activation analysis is used. The development
of the neutron
activation
analysis
method
R u c h et aL 3, 4 demonstrated that antimony, barium and copper are present as residues of fired ammunition on the hand which fired the weapon and they determined these elements for the first time by neutron activation analysis. Since then many authors have been interested in this field. K u b o t a et al., 5 S c o t t et al., 6 S c h l e s i n g e r et aL q and K r i s h n a n e t aL 8 have increased our knowledge on this subject. H o f f m a n 9 pointed out a simple method for collection of gunpowder residues from the suspects' hands by cotton swabs moistened with 5% nitric acid. B a u m g a r t n e r et aL 1I) by the NAA of antimony, determined the charge distance, and since then the development of a technique based on the NAA of antimony for the purpose of accurately determining firing distances in criminal eases received much attention by K r i s h n a n . 11,12 The problem of the identification of bullet holes has been added to the previous one by K r i s h n a n and N i c h o l . 13-15 The liquid paraffin drops for collecting mental nuclear activation assay
residues
and instru-
In the present investigation w e h a v e tried to improve the method for sampling and determination of gunshot residues~ The removing material is stiil paraffin but the technique is simplified and the amounts of antimony, b atiu m and copper are determined by instrumental NAA. The use of paraffin drops from a lighted paraffin candle directly onto chosen places of both the suspect's hands makes the method ideal for field usage, since the candle, provided it is protected from contamination by a polythene cover, can be carried in a pocket or bag very easily. The gunshot residues collection is quite inexpensive, requiring only that uncontaminated paraffin candle be used, that solidified drops from the same candle be kept as blanks and that the solidified paraffin drops collected from the suspect's hands be kept uncontaminated up to the instrumental NAA analysis.
Experimental Removal
of residue
for testing
The material for removing gunpowder residues is stiU paraffin as in the conventional method, but the technique used is easier. Instead of melting and application with a brush, which limits the collection of sample to given places and is time-consuming, paraffin was dropped from a lighted paraffin candle directly onto the skin. 52
i . RadioanaL Chem. 15 (1973)
G. BORRA et a l . : GUNSHOT RESIDUES
This technique may be usefully employed by police personnel because a c o m m o n paraffin candle and some plastic containers to store the samples are simple equipment for an investigative group.
C,
Fig. 1. Sampling position of right firing hand
Site
of sampling
Preliminary experiments were carried out to investigate the selective place of deposit of firearm discharge residues. Several test shots were fired using the same pistol and ammunition (Waiter 6. 35 and Fioechi, respectively) and the amounts of barium, antimony and copper were evaluated on many positions of the firing hand as shown in Fig. 1. In Table 1 the median amounts i n / , g of Ba and Sb on the different positions of the hand are mapped and reported. The sampling area is roughly 1 to 1. 5 cm 2. Considering the residues left on the positions B and C in the firing of ammunition, the first interdigital space of the hand w a s adopted as standard site of sampling. The standard procedure is to cover it with liquid paraffin dropped from a lighted paraffin candle onto an area of about 3 em 2, with a thickness of about 3 mm. Neutron
activation
analysis
The samples were irradiated at a flax of about 1 9 1012 n 9 cm "2 9 sec "1 for 3 hrs, together with standards of barium and antimony in the TRIGA Mark II (250 kW) reactor of the University of Pavia LENA Laboratory. After irradiation the samples were counted using a 20 cm 3 germanium-lithium crystal connected to a 4096-channel pulse-height analyser LABEN "correletron". J. Radloanal. Chem. 15 (1973)
53
G. BORRA et a l . : GUNSHOT RESIDUES
Due to the high resolution of Ge(Li) detectors c h e m i c a l separations are not n e c e s sary, the purely instrumental analysis of the g a m m a - s p e c t r a from the radionuclides obtained being sufficient for identification. Table 1 Map of the average amounts in p g of Ba and Sb on right firing hand a
Position A B C D E F G
Ba
Sb
0. 22 0. 24 0. 31 0,13 2.30 0.44 0. 07
N~ D .
Position
0.12 0. 14 0.07 0.07 0. 21 0.11
y
Ba
Sb
1.9 0.15 0. 31
0.11 N.D. N.D.
N. D. : not detected, less than 0.05 for Ba, l~ss than 0.01 for Sb. a For the identification of position refer to Fig. 1. The data were stored on m a g n e t i c tape and m a n u a l l y processed later. For the evaluation o f the barium concentration, the samples were counted after a one-hour cooling period and the area of the 0. 164 MeV g a m m a - p e a k of 139Ba was compared to that of the standard. For the antimony content the 0. 564 Mev g a m m a - r a y of 122Sb was compared to the standard after a cooling ~eriod of 24-36 hrs. The detection l i m i t with the adopted procedure is 0. 05 /~g for barium and 0. 01 /~g for antimony. In agreement with R o d i e r et aL 16 our preliminary experiments showed copper to be present as the residue of c o p p e r - j a c k e t e d bullets, but Its content in samples from "blank", non-firing and firing hands varies erratically. This e l e m e n t was therefore considered as not sufficiently reliable. Copper was d e t e r m i n e d by the 0. 511 Mev g a m m a - r a y e m i t t e d in the decay of 64Cu (T = 12. 8 hrs), after subtraction of the contribution due to the high-energy g a m m a - r a y e m i t t e d in the decay of 24Na, whenever present.
Results
Blanks
and
residues
after
firing
Preliminary experiments showed that the paraffin from an appreciable number of c o m m e r c i a l common candies is barium and a n t i m o n y - f r e e . Tests were also m a d e 54
J. Radioanal. Chem. 15 (1973)
G. BORRAet al.: GUNSHOTRESIDUES on the right and left hands of about fifty persons with different professions: students, p o l i c e m a n , technicians, physicians, and laboratory chemists, and in no case was antimony found at the site of standard sampling. In the case of barium, for ten individuals a concentration range from 0. 05 to 1 #g was found on at least one hand as shown in T a b l e 2. Table 2 Barium concentrations in #g on non-firing hands Subject No.
Right hand
Left hand
3 5 6 8 9 11 14 23 26 28
0.16 1.0 0. 14 0. 23 0.05 0.08 0.10 N.D. 0.10 0. 57
0.18 0. 20 N.D. N.D. N.D. N.D. N.D. 0.19 N.D. N.D.
N.D.: not detected, less than 0.05 for Ba, less than 0.01 for Sb.
In order to determine the amounts of barium and antimony deposits resulting from firing, test shots were carried out with different people and pistols. Table 3 gives the amounts, in micrograms, of barium and antimony found on the non-firing and firing hands of persom who had fired a p i s t o l Assays were also carried out on the forefinger of the right hand and the standard site of the left hand of a subject who had fired five shots with a m a c h i n e pistol (8eretta M 12) and the results were: forefinger, barium not d e t e c t e d , antimony not d e t e c t ed, left hand: barium not d e t e c t e d , antimony 0. 21 # g. The grips, held with the left hand, contain the m a g a z i n e of the m a c h i n e pistol, and therefore some leakage of high-pressure gas was expected at this p l a c e with consequent deposit of residues. Effect
of number
of shots
and
amount
of residues
No relation was found in the tests between the amount of barium or antimony and the number of shots. Many factors play an important role in the amount of residue, e . g . the humidity of the skin, the presence of hair, and the r e c o i l of the weapon. I. Radioanai. Chem. IJ (1973)
55
G. BORRAet al. : (TJNSHOTRESIDUES Table 3 Barium and antimony deposits in pg on bands after shooting
Subject No. 1 4 7 10 13 42 43 46 a 55 56 57 58 59 60 61 62 64 65 67 68 69 71 b
7% % 74 75 80
Amount of barium Pistol
Non-flrlng hand
Walter 6. 35 W a k e r 6. 35 Bexetta 7. 65 Beret~a 7. 65 BereRa 7. 65 Be.recta 22 Betet~a 22 Beret~a 22 W a l t e r 6. 35 Walter 6. 35 Walter 6. 35 Walter 6. 35 W a i t e r 6. 35 Waiter 6. 35 Waiter 6. 35 Waiter 6. 35 Berecta 9 Berecta 9 8execta 9 Berecta 9 Berecta 9 Berecta 9 8erecta 9 Berecta 9 Beret~a 9 Berecta 9 Beret~a 9
0. 37 N.D. N.D. N.D. 0.10 N.D. N.D. N. D. N.D. N.D. 0.30 N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.S. N.D. N.D.
Fh~ng hand 2.88 0.55 0.~ 0.88 2.51 13.31 0.18 0.40 0.62 N.D. 1.22 N.D. 3.~ N.D. 0.51 N.D. 0.50 0.30 0.14 N.D. N.D. 0.12
0. I0 N.D. N.~ N.D. N.D.
Amount of antimony Non-fixing hand
Fixing hand
N.D. N.D. N.D. N.D. N.D.
0.45 0.30 0.11 0.77 0. 59
N.D. N.D. N.D.
1.'64 0.14 0. 72
N.D. N.D. N.D. N.D. N.D. N.D.
0.58 0. 03 0. 57 0.03 2.82 N.D.
N.D. N.D.
1.20 0.25
N.D. N.D. N.D. N.D. N.D. N.D.
0.03 N.D. 0.06 0.04 N.D. N.D.
N.S. N.D. N.S. N.D. N.S.
0. 08 0.03 0.05
0.20 0.05
No. of shots 1 3 1 3 3 1 1 3 1 1 1 1 1 1 1 1 2 2 1 2 2 2 5 1 1 5 5
a The subject handled and charged the pistol. b The subjects handled, charged and fired the pistol only a few minutes previously. N.D.: Not detected, less than 0.05 for Ba, less than 0.01 for $b. N. S. : Not sampled.
56
.L RadloanaL Chem. 15 (1973)
G. 9ORRAet al. : GUNSHOTRESIDUES Effect
of washing
on residues
Several tests were made in order to establish the retention of the residues by the skin. Our experiments demonstrated that a mild washing with cold water leaves only amounts close to the detection limit. A normal washing soap or detergent removes the residues completely. Actual cases
In an attempt to verify the reliability of the method, some actual cases were examined with the proposed technique. Standard samples from a suicide case were analysed. No antimony or barium was detected on the non-firing hand, while on the firing hand 0. 30 and 0. 15 ~g,respectively, were found. In another clear-cut suicide case we were unable to find any barium or antimony, although test firings with the pistol involved in the case confirmed both barium and anO.mony on the firing hand. This fact was surprising. The next day we were informed by the police MD, a physician of the Forensic Medicine Institute, that the body had been washed and shifted from the scene of the shooting in an attempt by the family to conceal the e v i dence of suicide. In a suicide case with a rifle no residues were found, and this was confirmed after many experimental shots and standard samples. In a homicide-suicide case the amounts of antimony on the hands of both the victim and the murderer-suicide were determined: no antimony was detected on the left hands, whereas on the right hand of the victim we found 0. 12 ~g and on the murderer' s right hand 0. 31 /~g of antimony. Antimony on the hand of the victim is justified from the fight before her death. In a ease of triple murder a suspect was analysed by the "paraffin eolorimetric test" 4 days after the deed, with a positive result. No trace of barium or antimony was detected in the same samples by nuclear activation analysis, confirming the fact that the residues are removed with time and washing. Two persons were apprehended after a shooting conflict with the police force, and nuclear activation analysts of paraffin samples from their hands clearly showed that they had fired a pistol Discussion
It can be concinded from the data reported above that the presence primarily of antimony, and also of barium, both removed by paraffin drops from a hand which has fired a pistol, is evidence of firearm discharge residues. The blank, valmes of both hands are generally antimony-free, though barium has been found on some persons, depending on the cleanliness of their hands. Nevertheless the concentration difference of barium and antimony between the firing and nonJ. ~
.
Chem. 1.~ (197J)
57
G. BORRAet al. : GUNSHOTRESIDUES firing hands is generally significant in a decision as to whether one of the hands has fired a weapon. In the t reat m e n t of actual cases, as reported above, it is necessary always to take samples of both hands for a correct interpretation of the concentration values. It is also necessary, as reported above in an actual case, to carry out test shots using the same weapon and ammunition type because the deposits vary from one weapon ~r ammunition to another. In our method we have so far tested only pistols where leakage is expected to be present. More research with revolvers, rifles and other weapons is necessary to obtain a background of knowledge and to ascertain whether the method is of g e n e r a l application. It is unnecessary to add that should the method be adopted, carefully studied procedures for application must be enacted.
The authors would like to express their appreciation to Dr. P i e r u c c i , Associate Profegsor of Forensic and Imuranee Medicine at the Institute of Legal and Insurance Medicine of the University of Pavia, for his collaboration in supplying samples o! actual cases.
References 1. The Internal Revenue Service introduced this type of evidence in court in November 1967 in the case Ohio vs Watson. The defendant was tried on a charge of first degree murder in Cleveland, Ohio, and was found guilty. U.S. Department of the Treasury, Internal Revenue Service Publication.734, Jan. 1971. 2. S . S . K r i s h n a n , A . K . P e r k s o n , N . E . E r i c k s o n , Trans. Am. Nucl. Sot., 11 (1968) 79. 3. R . R . R u c h , V . P . G u i n n , R.H.Pinker, Tram. Am. Nucl. Soc., 5(1962) 282. 4. R . R . R u c h , V . P . G u i n n , R . H . P i n k e r , Nucl. Sel. Eng., 20(1964) 381. 5. M . K u b o t a , O . T o k u n a g a , Y.Nakamura,KagakuKe.LsatsuKenkyushoHokoku, 19 (1966) 261. 6. H . D . S c o t t , R.F.Coleman, F.H.Cripps, A W R E - O - f / 6 6 A W R E , 1966. 7. H . L . S c h l e s i n g e r . C.M.Hoffman, M . P r o , CA-8171, 1967, p. 189. $. S . S . K r i s h n a n , K . A . G i l l e s p i e , E . I . A n d e r o n , I. ForensicSci. 16 (1971) 144. 151. 9. C. M. H o f fm a n , Identification News, Oct. 1968. 10. F . B a u m g a r t n e r , H.Stark, A.Schontag, Z. Anal. Chem., 197(1963) 424. 11. S 2 S . K r i s h n a n , Tram. Amen Nucl. Soc., 9(1966) 88. 12. S . S . K r i s h n a n , G.A.-8171, 1967, p. 177. 13. S . S . K r i s h n a n , J. FommicSci., 12 (1967) 471. 14. S . S . K r i s h n a n , J. ForemicSci., 12 (1967) 112. 15. S . S . K r i s h n a n , R.C.Nichol, J.ForensicSci., 13 (1968) 519. 16. J. R o d l e r , R. E s t o u r n e l , C . V e r n h e s , Ann Med. Leg., 47 (1967) 796. 58
J. RadioanaL Chem. 15 (1973)
