September 24, 2008
The Police Chief Commissioner Christine Nixon says contamination of DNA evidence is always possible.
Victoria Police admits it can't guarantee DNA evidence used against alleged criminals will be free from contamination.
A review of the police DNA database was sparked after concerns over the validity of the DNA evidence against a man accused over a double murder in 1984.
A 43-year-old man was charged with killing Ferntree Gully woman Margaret Tapp and her nine-year-old daughter.
The police were forced to withdraw the charges against him.
A Forensic Services Department DNA audit of 6,000 cases has found only one other DNA sample, for a case involving car theft and the cultivation of drugs, may have been contaminated.
No charges were ever laid over the crime.
Speaking on the Fairfax News Network, Police Chief Commissioner Christine Nixon, said although DNA was an incredibly powerful tool there is always potential for contamination.
But she says procedures are in place to minimize the risk.
"They're accredited by national authorities, we have an external oversight board that has also looked at the material, and so we've got a range of people that are looking at this, " she said.
Ms Nixon said the Forensic Services Department has worked tirelessly to ensure the impact on all other forensic work was kept to a minimum.
"I would like to stress that the Forensic Services Department at Victoria Police is of world class standard," she said.
"They follow world best practice and employ professional, expert scientists who work with integrity, independence and professionalism."