Family tree

The popular use of the term DNA 'fingerprinting' has resulted from normal fingerprinting becoming synonymous with crime detection. In any case, DNA profiling, which is the correct term for the method used in investigating Naina Sahni's murder-(and many other cases), had an ancestor in the Inspector General of Police of the Lower Bengal Residency, Sir Edward Richard Henry of the British Raj in India. Vexed with thwproblem of keeping the attendance of employees of the East India Company in check he studied the fingerprints of the workers, who marked their daily presenc.e using left thumb impressions on the muster rolls.

Fingerprinting itself is based on traces of sweat, which can be recovered from anything touched by a person. But in the absence of a control sample (i.e. an already existing fingerprint specimen), the chances of positive identification remai In remote. Eventually, the world's first fingerprint bureau, based on Sir Henry's observations and principles, was set up in Calcutta in 1897.

Much later, scientists 'devised the technique of skull-super- imposition pictures - matching photographs of the deceased with postmortem pictures of her/his skull to establish identity. First used in the US in 1935, it operates on the premise that each skull is unique and one does not fit into another face.

However, this technique was not considered fool-proof, as some questions, like the angle of the photograph taken, and the magnified skull-photograph ratio, remained unanswered.