Forensic Science Leaps At Ground Zero

The victims' remains retrieved from the debris of World Trade Centre are too scarce to identify a victim. This situation, two years after the tragedy, has forced a group of forensic scientists to break new ground. Forensic scientists working on the project have devised techniques, which can extract data pretty quickly from extremely minute amount of biological samples. This helped in the identification process of the twin towers' victims. 

It is well known that the telltale sign of individuals' identity is embedded in their DNA. Every person has a unique DNA profile, which closely matches his parents and siblings. To identify a victim's remains, researchers compare DNA samples from bodies to those taken directly from victim - from a hair - or toothbrush, for example - or from a family member. But, for this forensic scientists need intact stretches of DNA, which contain several hundred chemical letters. A DNA molecule looks like a twisted staircase, whose rungs are made of four types of compounds - adenine, guanine, cytosine and thymine, which are known as chemical letters. 

Many twin towers body parts were too decomposed to yield such samples. The techniques devised by John Butler of the US National Institute of Standards and Technology in Gaithersburg, Maryland can deal with shorter stretch of DNA - about 100 letters long. "The techniques developed for the World Trade Centre will benefit the whole field," said Butler. Using the new methods, forensic scientists can identify decomposed murder victims in war zones like Iraq, Bosnia and Rwanda. 

Till date, 14,249 body parts have been recovered from the wreckage of the twin towers. Extracting DNA samples from these body parts, researchers are matching them to the 2795 people who have been killed by the terrorist attacks on the twin towers. So far, 1,484 victims had been identified. 

To accelerate the process of identification, the forensic scientists went a step further. Charles Brenner, a consultant forensic mathematician based in Oakland, California has written new software to search quickly for the strongest matches of DNA samples from all of the possible combinations. His study has been published in a recent issue of journal Theoretical Population Biology. 

Coincidental sharing of genes between unrelated people can lead to bogus match-ups. "For every parent that has lost a child, there are likely to be quite a number of victims, that are a plausible child of that parent," Brenner explained. "There will be about one false relative among every 1000 victims."

To solve this, Brenner stressed on collecting DNA from several relatives of each victim. It will reduce the chance of one victim's DNA profile matching both the father and mother of another victim. 

To be dead right in their identification, recently the research team added a new weapon to their armoury. The researchers zeroed in on individuals' distinctive single letter genetic changes, known as single-nucleotide polymorphisms (SNPs). Such single letter genetic changes can be identified just scanning a stretch of DNA containing 50 chemical letters. 

Though SNPs have been the focus of intense medical research, but are new to the field of forensic science. Using this technique, forensic scientists are identifying about ten new victims of the attacks each month. At this pace, the identification process may be wrapped up in a year's time.