People commit crimes invariably by using tools or things or weapons. In the process they interact with various physical things besides use of physical force in the form of bodily force or weapons. The Physical things involved in the process of committing crime can be a vehicle to reach the scene of crime, shoes for walking into the place, crowbar for bending the window bar, rope for tying the neck, knife for stabbing, stone for crushing, revolver for shooting, poison for killing, pen for forging, and bodily force for committing other crimes against persons and property such as rape, murder, burglary etc. In the process, the criminal leaves marks such as fingerprint, foot prints, blood, seminal stains, saliva stains, fibers, tool marks etc., at the crime scene besides leaving behind minute bits of evidence at the crime scene, on the victim and on himself or herself.

However careful a criminal may be to avoid being seen or heard, he will inevitably defeat his purpose unless he can also control his every act and movement so as to prevent mutual contamination with his environment. Wherever he steps, whatever he touches, whatever he leaves even unconsciously will serve as silent evidence against him. However careful and conscious he may be avoiding leaving signs and traces of his presence or actions and whatever precautions he may take in destroying the evidence of his presence, he is bound to commit mistakes inadvertently which will stand against him.

But location of all such minute bits of evidence which may sometimes be invisible or partially visible is difficult to accomplish for the Investigation Officers without appropriate tools for identification, lifting and collection. But the fact remains that there do exist some interactive evidence all through the space the perpetrator traverses.

  
At a time when eye witness's evidence is difficult to obtain, mainly because no one is willing to come forward to stand as eye witness and even in those few cases where the eye witnesses are available they may turn hostile at the time of adjudication it became necessary to look for alternative. Moreover due to phenomenal advancements in Science and Technology the smart new hi-tech criminal is able to commit crimes. Because of these complexities in the investigation of crime, many crimes now a days are remaining undetected and few other crimes where detection although becomes possible, due to technical trivialities and legal loopholes the criminal is escaping unpunished. The result of all this is many criminals are committing crimes repeatedly, undeterred and unchecked and thereby all law abiding citizens are losing confidence in the Criminal Justice Administration.

The Police in advanced countries are utilising latest scientific tools for identification and collection of all available physical evidence by qualified and skilled scientific personnel. The result of such scientific approach right from collection of Physical Evidence at the Scene of Crime to its examination in the Forensic Science Laboratories, objectively linking the crime with the criminal have not only improved the levels of detection but also enhanced the rate of conviction because of the infallibility of physical/clue/material evidence.

  
Crime scene is the fountain head of various forms of evidence, and such evidence must be collected at the earliest possible time as otherwise the evidence will be lost contaminated or altered. And it may not be found at all for the second or subsequent visits. The main purpose of this team is to reach the scene of crime immediately after report and undertake all steps for crime scene processing which include protecting, recording, sketching crime scene and thereafter search, identify and collect all available evidence. Apart from these permanent team members the services of Explosive experts, Ballistic experts and Medical expert etc. will be available whenever needed as stand by. The most important feature which helps the Investigating Officer in further investigation is availability of spot test kits for preliminary analysis of commonly encountered evidence materials such as blood, paint, narcotics, explosives, cloth, gunshot residue, ink, paper, dyes etc.

Since the criminals are becoming more and more smarter, even if they don't leave any visible, perceivable clues at scene of crime the invisible and hitherto improbable to lift/collect clues like fingerprints, tool marks, fibres, stains and other microscopic evidence can be easily searched, located, identified and linked with the criminal with the help of these state-of-art imported equipment is available with these teams.