Section 296(b) in Police Regulations, Bengal , 1943
(b)Every investigating officer shall observe the following instructions:-(i)Finger marks should invariably be looked for on glass, metal, polished wood, or lacquer work. Torches abandoned by dacoits should always be carefully examined, as good finger impressions are not infrequently found on the charred surface of the torch; upon bottle-torches such impressions are usually very clear. The fact that glass forms the best medium for finger impressions is of importance also in cases in which prostitutes are drugged for the purpose of robbery, the liquor being usually administered in an ordinary tumbler or bottle. In burglary cases finger impressions are often to be found on the bamboo matting near the point of entry, or on doorposts, and the portion on which the finger impression is found should be carefully cut out and forwarded for examination. In cases of murder immediate search should be made for blood-stained finger impressions. All investigating officers are supplied with a magnifying glass, which they should invariably carry with them on investigations.(ii)Finger marks on glass, polished wood, metal and lacquer work may be intensified by sprinkling the surface with a small quantity of a powder, known to chemists as "Gray powder", which should then be gently shaken or brushed off with a camel hair brush. Should the substances be white in colour, such as paper, wood, etc., "Graphite" may be used instead of "Gray powder". This treatment has the effect of making visible impressions which cannot be seen with the naked eye. Articles which may have been handled by criminals should always be treated in this way, if possible. These powders may be obtained from Bathgate & Co., Calcutta. Steps should be taken by the Superintendents to supply all police-stations with phials of "Gray powder" and "Graphite", the expenditure being met from the contract grant. Inspecting officers are required to see that their officers understand and follow these instructions.(iii)Objects appearing to bear impressions should be forwarded to the Criminal Investigation Department for opinion. Great care should be taken not to make other finger impressions on any such article forwarded. It should not be handled unless absolutely necessary, when something with a smooth surface should be slipped underneath. The article should be carefully lifted into the box in which it is to be packed, and nothing with a rough surface should be allowed to come into contact with the portion bearing the finger impression. Particular care should be taken in following these instructions in forwarding tumblers in poisoning and drugging cases.(iv)In important cases, or when exhibits are very heavy or large, they may be sent down by special messenger. Ordinarily the package should be sealed and sent by registered post to the Assistant to the Deputy Inspector-General, Criminal investigation Department. A label should be attached to each article, giving the name of the police-station, name of district, and the name of the officer forwarding the package, and every care should be taken that the identity of the exhibit can be proved, as in the case of articles sent to the Chemical Examiner.(v)When impressions are left on articles like safes or on walls, a telegram should be despatched to the Criminal Investigation Department asking for the services of an expert to intensify the impression, care being taken in the meantime to protect it.
