Malaysian Journal of Analytical Sciences Vol 23 No 2 (2019): 229 - 236

COLOURIMETRIC BASED DETECTION OF GUNSHOT RESIDUE ON GLOVES WORN DURING SHOOTING

(Pengesanan Sisa Tembakan Berasaskan Kolorimetrik pada Sarung Tangan Semasa Menembak)

Azie Azyanti Mohd Rafae¹, Saiful Fazamil Mohd Ali², Ahmad Fahmi Lim Abdullah¹, Kah Haw Chang¹*

¹Forensic Science Programme,

School of Health Sciences,

Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia

²Criminalistic Section, Forensic Division,

Department of Chemistry, Jalan Sultan, 46661 Petaling Jaya, Malaysia

*Corresponding author: changkh@usm.my

Received: 5 February 2018; Accepted: 16 February 2019

Abstract

Determining the shooter is an important element during investigation of firearm related offences, particularly through the detection of gunshot residue (GSR) as forensic evidence on shooter’s hand. However, such detection could be restrained if it is obstructed by the wearing of gloves by a shooter. Hence, it is worth investigating the presence of GSR on gloves, aiming to suggest an individual’s contact with a weapon. In this study, Modified Griess Reagent (MGT) commonly available in forensic laboratory was utilised to screen GSR on individual gloves of different materials worn by a shooter during a shooting training session. The experimental results revealed that both the palm and back of gloves equally allows the detection of GSR by MGT (p = 0.083). No statistically significant association was evident between the types of gloves and positive indication of MGT (p = 0.122). The types of firearms, neither revolver nor semi-automatic pistol showed significant association with the detection of GSR on the gloves (p = 0.248). When two-hand shooting was performed, glove samples worn on left and right hands gave almost similar testing results (p = 0.626). Although the presence of GSR on a glove after a shooting could be relatively low, the study has demonstrated that applying MGT, a simple test could assist crime scene investigation in determining the presence of GSR, in cases when gloves were used.

Keywords: forensic science, gunshot residue, colourimetric test, Modified Griess Reagent, glove

Abstrak

Pengenalpastian seseorang penembak adalah unsur yang penting ketika penyiasatan kesalahan yang berkaitan dengan senjata api terutamanya melalui pengesanan sisa tembakan (GSR) sebagai bukti forensik pada tangan penembak. Walau bagaimanapun, pengesanan sedemikian boleh dihalang sekiranya bahan-bahan tersebut terhalang oleh pemakaian sarung tangan oleh seseorang penembak. Justeru, adalah bernilai untuk menyiasat kehadiran GSR pada sarung tangan yang bertujuan untuk mencadangkan perhubungan seseorang individu dengan suatu senjata api. Dalam kajian ini, reagen Griess terubahsuai (MGT) yang lazimnya boleh didapati di makmal forensik telah digunakan untuk menyaring GSR pada setiap sarung tangan yang diperbuat daripada pelbagai bahan yang berbeza dan dipakai oleh penembak ketika suatu sesi latihan tembakan. Keputusan eksperimen menunjukkan bahawa kedua-dua permukaan tapak and belakang sarung tangan sama-sama membenarkan pengesanan GSR oleh MGT (p = 0.083). Tiada perkiatan statistik bererti terbukti antara jenis sarung tangan dan penentuan positif MGT (p = 0.122). Jenis senjata sama ada revolver atau pistol separa automatik tidak menunjukkan perkaitan bererti dengan pengesanan GSR pada sarung tangan (p = 0.248). Apabila penembakan dua belah tangan dijalankan, sampel sarung tangan dipakai pada tangan kiri dan tangan kanan memberikan keputusan ujian yang hampir sama (p = 0.626). Walaupun kehadiran GSR pada suatu sarung tangan selepas suatu tembakan berkemungkinan agak rendah, kajian ini telah menunjukkan bahawa penggunaan MGT yang merupakan suatu ujian yang mudah dapat membantu penyiasatan tempat jenayah dalam penentuan kehadiran GSR, terutamanya dalam kes-kes apabila sarung tangan telah digunakan.

Kata kunci: sains forensik, sisa tembakan, ujian kolorimetrik, reagen Griess terubahsuai, sarung tangan

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