Gunshot residue

Source Christensen, A. M. Experiments in the Combustibility of the Human Body. Journal of Forensic Sciences 47 (2002), 466-470. 

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Gunshot/Residue Results as Determined from Test Firings. 

In the field of forensic technology, there has long been a considerable need for detecting gunshot residues on the hands of an individual suspected of having fired a gun in a criminal act. 

The pertinent neutron activation data for the determination of Ba and Sb in gunshot residues by (n,y) thermal neutron activation is given in Table 8... 

As stated earlier, when gunshot residues are removed from the back of the hand of a person who has recently fired a gun, other material present on the skin, in particular considerable amts of Na chloride, are also removed, and that the activated... 

Paraffin Coating Method for the Removal of Gunshot Residues from Hands... 

The thumb-web area, referred to in the above procedure is the V-shaped section formed by the surfaces on the back of thumb, the trigger finger and the area between the thumb and trigger finger. Controlled firing tests show that the bulk of the gunshot residues are deposited on this area of the back of the hand... 

A highly important factor in the interpretation of gunshot residue analyses is the presence of either Ba, Sb or both on a person s hands from sources other than the firing of a gun, eg, from materials encountered in their normal occupation. An extensive investigation of such handbiank measurements was conducted by GA involving... 

A Del Electronics, Model ESP-100A, electrostatic precipitator was used for sample collection. Cigarette smoke particles were found to give approx the same particle distribution pattern on the collection filter paper as the gunshot residue, and since the smoke stains the paper, this provided a v rapid technique for optimizing operation conditions. With a flow rate of 15cfm and a corona current of 125 uA, the residue collects primarily on a narrow band across the sample paper. Samples were collected on Whatman No 1541 filter paper which lined the inside of the sample collection tube. The presence of this paper allowed air to flow only thru the center of the tube, so particle collection was made upon the filter paper exclusively. The filter paper samples were pelletized prior to neutron activation analysis... 

Sb and Ba are present in the airborne gunshot residue expelled from all of the brands of 0.22 cal ammo. A chemical analysis of the primer. of the Western brand gave a Ba to Sb ratio of 65, whereas the same ratio obtained from the data in Table 11 is 2.6. The authors conjecture that this additional Sb left in the air came from the vaporized bullet Pb which contains a large amt of Sb as a hardening agent... 

Fig 10 shows the variation of airborne gunshot residue collected at various times after one firing. Following a general initial exponential fall-off, the rate of decrease slows at 48 hrs after firing. 

Firing tests conducted with larger than 0.22 cal ammo showed that even greater sensitivity for detection of Ba and Sb in airborne gunshot residues... 

Detection of Gunshot Residues on Floor Surfaces In another study at the Pennsylvania State University (Ref 20), gunshot residues from firing tests were assayed in order to establish distribution patterns of Ba and Sb on surfaces below the flight path of the buliet... 

Bratin, K., P. T. Kissinger, R. Briner, and C. Bruntlett. Determination of nitro aromatic, nitramine, and nitrate ester explosive compounds in explosives mixtures and gunshot residue by liquid-chromatography and reductive electrochemical detection. Anal. Chim. Acta 130, 295-311 (1981). 

It should be noted that a comparable survey and assessment task in the gunshot residue detection area recently has been completed by Aerospace. The long-range objectives of this research program are to develop rapid, reliable and inexpensive techniques and equipment for use by crime laboratories in the detection of gunshot residues on the hands of suspects. 

A Comparison of Neutron Activation Analysis and Atomic Absorption Spectroscopy on Gunshot Residue... 

Referring further to Table III, it is clear that not every firing of the test weapon led to a positive indication of gunshot residue. Any or all of several factors may account for the 15 incidence of "non-positives" in this study. One is variability in the spatial distribution of gunshot residue from one firing to another. A second involves non-reproducibility... 

Guinn, V. P. "The Determination of Traces of Barium and Antimony in Gunshot Residue by Activation Analysis" Gulf General Atomic Report GA 8171 San Diego, (1967)... 

Cone, R. D. "Detection of Barium, Antimony and Lead in Gunshot Residue by Atomic Absorption Spectrophotometry" presented at the Spring Meeting of the Southern Association of Forensic Sciences, (1973)... 

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