ORIGINAL ARTICLE
有个性的个性签名
Visualization of latentfingerprints using silica gel G: A new technique
Kulvir Singh,Sahil Sharma,Rakesh K.Garg*
Department of Forensic Science,Punjabi University,Patiala147002,India
Received25July2012;revid17September2012;accepted28September2012
重映射扇区计数警告
Available online9November2012
KEYWORDS
护理安全
Latentfingerprints; Development;
Silica gel G powder; Substrates;
Powder method; Conventional powders Abstract There are various methods available for the development of latentfingerprints on differ-ent substrates.This paper prents a new powder method for the development of latentfingerprints on different substrates.In this study,a less expensive,simple an
d easily available,silica gel G pow-der(usually ud in TLC plates preparation)has been ud to develop the latentfingerprints on eight commonly encountered different ,plastic,glass,ordinary mirror and metallic substrates,aluminium foil sheet,carbon paper,matchbox,cardboard,glossy-painted wooden sub-strates,top and writable surface of CD and glazed coloured magazine paper surface.It is obrved that it gives very clear results on most of the substrates with clear ridges.
ª2012Forensic Medicine Authority.Production and hosting by Elvier B.V.All rights rerved.
1.Introduction
In forensic investigations,fingerprints are considered a very valuable type of physical evidence.Fingerprints are found in majority of the crime scenes.The latentfingerprints,deposited by the ridges of thefinger or palm are a complex mixture of natural cretions and contaminants from the environment. Three types of glands are responsible for the natural cretions of the skin:the sudoriferous eccrine,apocrine glands,and the baceous glands.The three types of glands have well-de-fined functions,and the composition of their cretions varies in conquence.The sudoriferous glands are distributed all over the body and produce sweat that consists of more than 9
8%water.1The composition of latent print residue includes: chloride,calcium,sulphur,urea,lactic acid,amino acids,phe-nol,sodium,potassium,and ammonia,cholesterol,free fatty acids,wax esters with diglycerides,triglycerides,etc.2The development and visualization of latentfingerprints on some unusual substrates have remained a challenge to forensic scien-tists.Various methods are available to develop the latentfin-gerprints in the literature.Recently the hydrophobic silica bad particles had been developed to visuali latentfinger-prints.3However the traditional method for developing thefin-gerprints is the powdering method.4In this study a new material(powder)has been identified which can be ud for the development of latentfingerprints prent on both nonpo-rous and porous substrates.In this work silica gel G powder, that is ud to prepare the thin layer chromatography(TLC) plates,is ud.This powder is easily available for the labora-tory work.
Silica gel G powder is a form of silicon dioxide(silica)with the binder gypsum.The silicon atoms are joined via oxygen
*Corresponding author.Mobile:+919417522223;fax:+91
1752283073.
E-mail address:in(R.K.Garg).
2090-536Xª2012Forensic Medicine Authority.Production and hosting by Elvier B.V.All rights rerved. dx.doi/10.1016/j.ejfs.2012.09.001
Showing comparative visualization of latent fingerprints on glass surface with silica gel G powder (a)white powder (c)black powder (d).
Showing comparative visualization of latent fingerprints on ordinary mirror with silica gel G powder (a)white powder (c)black powder (d).
Showing comparative visualization of latent fingerprints on plastic surface with silica gel G powder (a)white black powder (d).
plastic paper),glass (plain glass and brown bottle glass),or-dinary mirror,metallic substrates (perfume can and currency coin),aluminum foil sheet,gloss-painted wooden substrates,top and writable surface of CD,polythene and a mi-porous
Showing comparative visualization of latent fingerprints on aluminium foil sheet with silica gel G powder (a)white powder (c)black powder (d).不要讲话打一字
Showing comparative visualization of latent fingerprints on a transparency sheet with silica gel G powder (a)powder (c).
Showing comparative visualization of latent fingerprints on perfume can with silica gel G powder (a)white Showing comparative visualization of latent fingerprints on brown glass bottle with silica gel G powder (a)white powder (c).
glazed coloured magazine paper surface.The porous sub-strates ud in this work are carbon paper (writing and inked surface),matchbox,white paper,currency note and card-board.The prints were left for half an hour in the laboratory conditions at room temperature after deposition.The exper-iment was conducted in the mid of the months of February and March.The temperature and relative humidity during the months ranged from 10to 25°C and 50.2%to 51.4%,respectively.The silica gel G powder (white in col-our)manufactured by Merck Specialties Private Limited was ud to develop the latent fingerprints on all the differ-ent substrates.The ordinary brushing method was not ud in this work.Few grams of the silica gel G powder was taken on the clean and dry glass plate and then
the powder layer was flattened using the glass rod.The latent fingerprint was developed by slightly pressing the latent fingerprint bearing surface on the sil-ica gel G powder layer.It is a physical method of enhancement of latent prints and works on the mechanical adherence of the fingerprint powder particles to the oily components of the skin ridge deposits.Application of powder to the print by brushing is a simple and an easy technique but it also has disadvantages that the brush on coming in contact with the surface having the print destroys the print and hence the ridge characteristics get destroyed.The excess of powder was removed by gently tap-ping the surface.The conventional powders available in finger-
Showing comparative visualization of latent fingerprints on CD’s writable surface with silica gel G powder (a)powder (c).
Showing comparative visualization of latent fingerprints on gift wrapping plastic paper with silica gel G grey powder (c).
Showing comparative visualization of latent fingerprints on CD’s top surface with silica gel G powder (a)powder (c).
print kit such as white powder,lightning grey powder and black powder were ud for comparative st
udy.
3.Results and discussion手的画法
The results of the prent studies are shown in Figs.1–13.The latentfingerprints on different substrates were successfully developed by using silica gel G powder in majority of the cas. It was interesting to note that the silica gel G powder gives bet-ter results on contrast substrates.The latentfingerprints pres-ent on substrates such as plastic,glass,ordinary mirror,and metallic substrates,aluminium foil sheet,carbon paper,match-box,cardboard,gloss-painted wooden substrates,top and writable surface of CD and glazed coloured magazine paper surface,were developed and showed clear ridges as is evident from thefigures.It has been found that latentfingerprints on cardboard were also visible after development and using this method the ridges were clear to read.It has also been found that after developing the latentfingerprint on the top and writ-able surface of CD,the data in the CD were not affected and it
Showing comparative visualization of latentfingerprints on glazed coloured magazine paper with silica gel G grey powder(c).
素服
Showing visualization of latentfingerprints with silica gel G powder on glossy-painted wooden substr呦呦系列
ates(a)currency (c)and cardboard(d).
芹菜饺子Showing comparative visualization of latentfingerprints on carbon paper with silica gel G powder(a)white
