THE EFFECTIVENESS OF SOOT REMOVAL TECHNIQUES FOR THE RECOVERY OF FINGERPRINTS ON GLASS FIRE DEBRIS IN PETROL BOMB CASES

Abstract The increased use of petrol bombs as an act of vengence in Malaysia has heightened awareness for the need of research relating physical evidence found at the crime scene to the perpetrator of the crime. A study was therefore carried out to assess the effectiveness of soot removal techniques on glass fire debris without affecting the fingerprints found on the evidence. Soot was removed using three methods which were brushing, 2% NaOH solution and tape lifting. Depending on the visibility of prints recovered, prints which were visible after soot removal were lifted directly while prints that were not visible were subjected to enhancement. Glass microscope slides were used in laboratory experiment and subjected to control burn for the formation of soot. Soot was later removed following enhancement of the prints over time (within 1 day, within 2 days and after 2 days). While in simulated petrol bomb ground experiment, petrol bombs were hurled in glass bottles and the fragments were collected. Favorable results were obtained in varying degrees using each soot removal methods. In laboratory testing, brushing and 2 % NaOH solution revealed fingerprints that were visible after removal of excess soot and were lifted directly. As for tape lifting technique, some prints were visible and were successfully lifted while those that were not visible were subjected to superglue fuming for effective fingerprint identification. Keywords: Soot removal, Glass, Petrol bomb, Brushing, NaOH wash solution (2%), Tape lifting Abstrak Penggunaan bom petrol sebagai alat untuk membalas dendam yang semakin meningkat di Malaysia telah menimbulkan kesedaran untuk kajian mengenai bahan bukti fizikal di tempat kejadian yang dapat dikaitkan dengan penjenayah. Maka, satu kajian telah dilakukan untuk menilai keberkesanan teknik penyingkiran jelaga pada kaca tanpa merosakkan cap jari yang berada pada bahan bukti. Jelaga disingkirkan dengan menggunakan tiga kaedah, iaitu memberus, larutan NaOH 2 % dan pengangkat pita. Bergantung kepada ketampakan cap jari yang ditimbulkan, cap jari yang tampak selepas penyingkiran jelaga akan diangkat terus manakala cap jari yang tidak tampak akan ditimbulkan. Sisip kaca mikroskop telah digunakan dalam uji kaji makmal dan dibakar dalam pembakaran terkawal untuk pembentukan jelaga. Jelaga disingkirkan dan diikuti dengan penimbulan cap jari dalam tempoh tertentu (dalam masa 1 hari, dalam masa 2 hari dan selepas 2 hari). Manakala dalam simulasi bom petrol, bom petrol yang terisi dalam botol kaca telah dilontar dan fragmen-fragmennya dikutip. Keputusan yang memuaskan diperoleh pada tahap yang berbeza menggunakan setiap jenis kaedah penyingkiran jelaga. Dalam uji kaji makmal, kaedah memberus dan larutan NaOH 2 % telah menimbulkan cap jari yang tampak selepas menyingkirkan jelaga yang berlebihan dan direkod terus. Dalam kaedah pengangkat pita, sebahagian cap jari adalah tampak dan berjaya direkod manakala sebahagian cap jari yang tidak tampak diproses dengan kaedah pewasapan superglue untuk penimbulan cap jari