Forensic Services

Familial Searching

Familial Searching uses the National DNA Database to identify possible close relatives of an offender when they are not present on the Database themselves. The technique relies on genetic inheritance principles that mean a parent will share half of their DNA with an offspring and siblings will share significantly more DNA than unrelated individuals. The high degree of coverage offered by the National DNA Database, (approximately 1 in 20 of the population has been sampled) means that it is possible for an offender who is not on the Database to have a close relative who is. A list of individuals who may be related to the true offender can provide investigators with a valuable intelligence tool.

The technique has been used successfully in a number of high profile cases. On of the earliest was the conviction of Jeffrey Gafoor for the murder of Lynette White in Cardiff in 1988. A DNA profile thought to be from the offender was detected on a number of items at the crime scene but the profile didn't match anybody on the National DNA Database. Using Familial Searching techniques the police were led to a close relative of Gafoor who had been sampled. Subsequently when a sample was obtained from Gafoor a full match against the crime scene profile was obtained.

The main relationships that familial searching can detect are parent/child and siblings. It is useful in serious cases where a full DNA profile of the offender has been obtained from the crime scene and no matches are obtained from a Database search or Intelligence Led Mass screen. Agreement to use the technique has to be given by an ACPO rank officer. This technique has been used around 80 times between July 2003 and June 2005. Its value was demonstrated in identifying the person responsible for the murder, 30 years ago, of three teenage girls in South Wales. It was also successfully used in the investigation into the murder of Michael Little, a lorry driver who was killed in March 2003 when a brick was thrown from a bridge through his windscreen.

A familial search will produce a list of many possible relatives. None of these individuals match the crime scene profile and most will have no connection with the criminal. The investigation team needs to be aware of the ethical implications that this information holds and have a strategy planned to use additional factors such as the geographical location, age and ethnicity to filter the results.