Son's genes prove dead man top Tiger: Lanka

Shortly after Tuesday noon, reports quoted Sri Lankan defence sources as saying DNA tests had confirmed that the body recovered from near the Nandikadal lagoon in north-eastern Sri Lanka earlier in the day was that of LTTE leader Prabhakaran.

Close-up photographs of the face left little doubt, but how did they establish it through DNA fingerprinting? What tissue did they have to refer and compare the DNA collected from the body?

There was no sample from Prabhakaran���s own body collected anytime earlier. Neither were there samples of his father or mother. The reference material could have come from the DNA samples of Prabhakaran���s son Charles Antony, whose body the authorities claimed to have recovered on Monday. DNA fingerprinting is vital, as several countries including India are likely to ask for Prabhakaran���s DNA profile for closure of cases including the Rajiv Gandhi assassination.

State-of-the-art laboratories worldwide use a technique called short tandem repeats (STR) of sequences of DNA by amplifying some regions of the DNA strand using polymerase chain reaction (PCR). This is the standard test followed in cases of paternal disputes. There are 23 pairs of chromosomes in a human cell, including 22 pairs of autosomes and one pair of sex chromosomes. A person inherits 50% of chromosomes from the father and the rest from the mother.

What could be clinching scientific evidence in such cases would be to compare the son���s samples with those of the mother���s too, to see if the DNA sequence matches with that of both the parents. But, in this case, samples of Prabhakaran���s wife Mathivadani were not available.

���Another opportunity here is the Y chromosome amplification technique,��� said Lalji Singh, director of Centre for Cellular and Molecular Biology. ���If they are father and son, sequences in the Y chromosomal strand should match 100%, as the Y chromosome is found only in males and is inherited by a male from his father.���

Experts, however, are not sure if Colombo could have done such a high-end analysis in such short a time. ���They (Sri Lanka) have not explained the method they have followed. To my knowledge, there is no sophisticated lab there which can do the technique so fast,��� Singh said.