Crime scene investigation: How to collect physical evidence

Crime Scene Investigation 

Crime scene investigation is a very sensitive issue anything doing wrong spoil the physical evidence and its an injustice to the victim. If not collected carefully than its not leads to a fruitful information. Physical evidence should be collected in an organised manner so that chances of loss , contamination and distortion are minimum. The  basic techniques used for collecting evidence are  -

1) Handpicking  -

In this technique we give preference to large exhibits which easily picked by hands. We Use tweezers and use hands (wearing gloves) for collection of macroscopic evidence. The simplest method of evidence collection. For picking up of paint particles a moisten brush having good hair is used. Its the simple technique used in crime scene investigation  for collecting evidence.

2) Swabbing  -

Swabs poured with distilled water are used to collect body fluids. Dry swabs are used to collect minute particles.  Fiberous swab are used to collect particulate matter. Cotton threads and cotton cloths are also used for body fluids collection. 

3) Sweeping -

This technique is useful for collecting evidence from a large and open place. By this technique we examine a car , house , bus , garage , hall etc. One of the major requirement for sweeping is a new paint brush and use separate brushes to avoid any contamination. 

4) Vacuuming  -

In crime scene investigation for collecting evidence , this technique is used for micro evidences and in this technique a specialized nozzle is attached with a Vacuum cleaner and by suction materials collected on traps. It is used on carpets , hidden parts of sofas etc.

5) Tape lifting  -

  In this technique a transparent adhesive tape is used to lift micro-traces from the crime scene. Traces  get attached to the adhesive surface and then placed to transparent glass or rigid plastic . Packed them in a plastic bag with proper labeling. Always avoid overlapping of tapes . By using this technique we lift micro-traces from motor vehicle floor , from its seat , carpets and from any garments , sofa cover etc.

By using these techniques we are collecting evidence from crime scene.

Some importance points to be considered before applying these techniques  - 

Larger article's scrutinized first. 

Floor should examined first for foot or shoe prints.

Before applying powder technique of fingerprints, blood and microscopic evidence should be collected. 

Before applying these techniques all visible trace materials like hair , fibers etc should be collected. 

Tape lifting always done before removing of dead body.

Always look out about quantity of material collected , it is better to collect excess of material. In some cases control sample is necessary. If comparison between two substances is required than a reference sample always be provided.

Avoid contamination of crime scene by the investigator himself as it is a possibility that hair sweating etc add to the scene by investigator body.

A systematic and organized approach to crime scene investigation and in collecting evidence reduce stress and fatigue and results in minimal loss and contamination of physical evidences.

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About forensic fingerprint

MR. DEEPAK PAWAR has been working as Finger Print Expert / Police Officer in Finger Print Bureau , Delhi Police at New Delhi since 2001 . He is the senior most Finger Print Expert , attending / visited several scene of crime and solved many crime cases .He has passed M.Sc (Chemistry) and he is the Member of International Association of Identification . He is the Member of Delhi Police welfare association . He is supervising the Forensic , New Delhi District , Mobile Crime Team . He is one of the Expert in the Special Investigation Team held for investigation of important cases . He has been giving fingerprint proficient training to Delhi Police personnel's . He has been Presented / giving lectures on topics related to forensic science . He is also making examination paper of Finger Print proficient course . He is awarded with Police Medal by MHA and Delhi Police.

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