Nearly 12 crime branch officers and two from the general branch are currently being trained in the techniques of lie detection by Professor Sibi George and Dr Richard Poe of the International Training Centre. Other police officers will soon join the training programme.

``In three months' time, our officers will be fully equipped to use the lie detection techniques,'' a senior crime branch officer said.

The polygraph test is widely used in the United States of America (USA) and other countries. However, in India, only the Ahmedabad Foresic Sciences Laboratory has so far availed of the lie detection techniques.

``By this technique, it will be very easy to detect that acriminal is lying. A little bit of sweat around his thumb area, delay in answering questions, increase in heartbeats and even the amount of pressure he exerts on his elbows while sitting will give away his lies,'' Professor Sibi George said.

Before conducting the test, electrodes are fitted on to the chest, abdomen, arms and thumbs of the accused. The accused is then supposed to answer questions only in the affirmative or negative. There has to be a space of 25 seconds between two questions. This time gap is crucial to bring about a natural change in the accused. The physiological changes amplify on the screen, and the machine records these changes and issues a printout. The lies of the accused can be determined in one session, at the least, or three, at the most, Prof George noted.

``The minor changes in the psychological and physiological behaviour of an accused will expose the criminal's lies,'' said assistant police inspector P Lonandkar, one of the officers who is undergoing training.

The polygraphreports cannot be used as independent evidence in a court of law. However, ``the polygraph reports, along with other evidence, can be used as additional evidence which will strengthen the case,'' said assistant police inspector Madhav Pradhan of the general branch.