DNA fingerprinting techniques 'can sometimes give the wrong results'

This is a pretty alarming study

DNA evidence is not an infallible tool for criminal investigations, experts have warned. Interpretation of samples can be highly subjective and prone to error, a study has found.

The incredibly small amounts of DNA in samples and pressure to gain a conviction can lead to bias, according to an investigation by New Scientist.

The magazine sent a sample of DNA from a real crime scene to 17 experienced analysts in an U.S. laboratory. The experts' differing results cast doubts over the technique's reliability.

The sample, from a gang rape, had already been used to convict a man - but only one of the 17 scientists came to the same conclusion. Four said the evidence was inconclusive and 12 said he could be excluded.

Itiel Dror, a University College London scientist who helped set up the investigation, said: 'It is time DNA analysts accept that under certain conditions, subjectivity may affect their work.'

Christine Funk, a defence lawyer in the U.S., said: 'The difference between prison and freedom rests in the hands of the scientist assigned the case.'

The chances of two people having the same DNA fingerprint are between 800,000 and one billion to one. But there are concerns that increasing reliance on tiny samples of blood and saliva, often from more than one person, leaves interpretation open to the scientist's judgment.

New Scientist added: 'Profiling is generally seen as infallible and always able to get its man. But DNA profiling is far from perfect.'

British experts said techniques used here are more advanced and highly regulated. Kay Francis, of the government funded Forensic Science Service, which handles the bulk of the police's forensics work, said: 'The UK has led the world in terms of breakthroughs in forensic science. North America is quite a bit behind in that aspect. 'A case is never hung solely on DNA evidence. The Crown Prosecution Service is very clear that nothing will go to court on just DNA evidence.'

Original report here



(And don't forget your ration of Wicked Thoughts for today. Now hosted on Wordpress. If you cannot access it, go to the MIRROR SITE, where posts appear as well as on the primary site. I have reposted the archives (past posts) for Wicked Thoughts HERE or HERE or here