Forensics, the science of finding a killer

Importance of scientific evidence in Yeates case may refocus attention on decision to break up Forensic Science Service
Forensics officer
Forensics officer removes evidence from the flat of Joanna Yeates in Clifton, Bristol. Photograph: Tim Ireland/PA

Forensics, the science of finding a killer


From the moment Joanna Yeates's body was found, detectives emphasised how important scientific work would be in establishing how she had died and convicting her murderer.

It was why the postmortem examination took longer than expected: the frozen body had to be thawed with care so that no scrap of evidence was lost. "We only have one chance to get it right," one senior officer said.

And it is why Avon and Somerset police continued today to painstakingly search Yeates's flat and that of her landlord, Chris Jefferies, who was arrested on suspicion of her murder.

At one point a sign was set up outside the building warning people not to enter because a laser was being used - such equipment can detect traces of material not visible to the naked eye or be utilised to take precise measurements.

Careful checks have also been carried out on the roadside verge where Yeates' body was found on Christmas morning and the nearby quarry and woods. Forensic experts are taking cars parked on Jefferies' drive and on the street outside his house to pieces. They will be looking for DNA information from hair or traces of skin and manmade fibres that can be analysed, characterised and matched.

The importance of scientific evidence in the case may refocus attention on the government's decision to break up the Forensic Science Service (FSS), which is involved in about 120,000 cases a year.

Forensic scientists, police and victim support groups have expressed surprise and anger at the move, pointing out that the FSS has helped convict high-profile killers such as Ian Huntley, Roy Whiting and Steve Wright. Among the critics is Sara Payne, the mother of Sarah Payne, eight, who was murdered by Whiting.

Ms Payne, who campaigns on child abuse issues, said: "Ninety per cent of most current sex offender cases rely on forensic services to prove their cases. Roy Whiting, and countless other offenders I can think of, would not be in jail if it were not for the FSS."

A group of 33 experts including Professor Sir Alec Jeffreys, who pioneered DNA fingerprinting, signed a letter claiming the justice system would take a "backward step". They said services provided on the free market rather than by the government-owned company would not provide some more expensive forms of analysis crucial to police investigations. Sir Alec called the FSS "an absolute flagship of British forensic science" and called the government decision "quite bizarre".

Other notable cases the FSS played a big part in was the hunt for schoolgirl Shannon Matthews in 2008. The FSS is also proud of its work in the case of Lesley Molseed, who was murdered in 1975 in West Yorkshire. In 2007 Ronald Castree, 54, was convicted of her murder after detectives took a sample of his DNA when he was arrested on suspicion of rape. FSS investigators matched it to a sample retained from the original Molseed investigation.

The government insists the FSS is making "significant and unsustainable operating losses" and says it is confident effective forensic services will still be provided.