Tamanna Jaitly

Fingerprints are an important piece of evidence in crime investigation and play a key role in crime investigation due to their permanency, universality, uniqueness and of course availability. Utilization of water or any other liquids to destroy evidence by criminals is a very common practice. It becomes difficult to collect and analyse such evidence from underwater in terms of its forensic reproducibility, though not impossible. The methods employed are quite tedious, expensive and unreliable. There are many fingerprint powders accessible to the scientific examiners to recuperate and gather the unique fingerprint impressions submerged, the vast majority of them are for explicit materials like small particle reagent (SPR). The technique has been compromised by its downsides as it is highly toxic, very sensitive, low contrast and quite costly. An urgent and imperative need to foster an economical and effective, low cost fingerprint powder for underwater impressions by using the materials that are easily available. The present study was conducted to fulfil the same objective and proposes a modest unique fingerprint powder which provides great proficiency from a combination of surfactant sodium dodecyl sulphate (SDS) with chalk powder (yellow) and silver powder respectively.

Polycarbonate is widely used as structural material due to its extreme resistance to impact and perforation. In a crime involving firearms, the bullet may impact various objects fitted with or made of polycarbonate sheets leaving high chances of discovering the fractured PC sheets and fragments at the scene of crime; hence, these objects may become objects of the criminal investigation. In the present work the perforation pattern of PC sheets of thicknesses 8 mm, 10 mm, 12 mm and 15 mm at firing ranges 5 m and 10 m when impacted against 9 ×19 mm full metal jacket (FMJ) bullet were examined. It was observed that after impact, the PC sheet develops entry hole smaller than the calibre of bullet; formation of crack zone, plastic zone; and petalling on the distal face was observed. It was found that as the thickness of the sheet increases, the diameter of the entry hole increases, the diameter of the exit hole initially increases and then becomes constant. At 5 m range of fire the trend of crack zone becomes nearly constant from 8 mm to 15 mm thickness, however, at 10 m range of fire crack zone increases from 8 mm to 15 mm thickness. Furthermore, the diameter of the plastic zone increases as the thickness of the sheet increases (from 8 mm to 15 mm, respectively).