Forensic scientists in the UK are developing a method of linking DNA evidence from a crime scene to the surname of the perpetrator.
This might enable investigators to narrow the scope of an investigation by focusing on suspects with certain names. But some experts question whether such an approach would be feasible in practice.
Researchers at the government鈥檚 Forensic Science Service, based in Birmingham, UK, are conducting studies to determine whether extracting potential surnames from genetic evidence would help a criminal investigation.
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The technique is based on the concept that men should inherit both a Y chromosome and a surname from their father. Broadly speaking, men with matching surnames are also likely to have matching Y chromosomes. Female criminals have nothing to fear from the technique as they have no Y chromosome.
Important sequences
David Werrett, chief executive of the Forensic Science Service, says new techniques for analysing Y chromosomes should make this surname matching possible.
Y chromosomes can be compared by matching certain key characteristics, or markers. Typically 20 of these should be good enough to match two chromosomes accurately. 鈥淲e want to get to the point where we know which genetic sequences are important,鈥� he says.
However, Mark Jobling, a DNA fingerprinting expert at Leicester University, UK, says various practical complications could make surname-matching inaccurate.
One potential problem is that the some surnames have multiple origins, and will therefore be linked to numerous Y chromosomes. Names derived from a particular trade for instance, like Smith, will probably represent a number of different lineages.
Expensive maintenance
The other main complication is that Y chromosomes will not always be inherited along with a surname. This may be due to illegitimacy, because someone takes their mother鈥檚 name, or perhaps because they are adopted.
The surname-matching approach might work for relatively unusual surnames, says Jobling. 鈥淚鈥檓 a bit sceptical,鈥� he told New Scientist. 鈥淚 think you鈥檇 need a very large database for it to be effective and that would be very expensive to maintain.鈥�
But the UK鈥檚 National DNA Database now holds more than 2.7 million DNA samples, making it the most comprehensive catalogue of its kind in the world. And data is being added to it at an increasing rate, after the UK government changed the law in 2004 to allow DNA samples to be taken from people who have been arrested as well as those who are charged or convicted with a crime.
Genetic evidence can already be used to identify a suspect through a family member. This 鈥渇amilial searching鈥� technique was used in April 2004 to secure the conviction of a killer traced through a close relative鈥檚 DNA.