New DNA evidence discovered on one of the Wanda Beach murder victims is at least five years away from being useful, police say.

A weak DNA profile of an unknown male has recently been identified from a pair of jeans worn by one of the victims, the Acting Assistant Commissioner of the forensic services group, Mark Sweeney, told reporters in Sydney on Monday.

But new technology needs to be developed before a conclusive match can be made, he said.

Marianne Schmidt and Christine Sharrock, both aged 15, were found beaten and stabbed to death at the beach in January 1965.

'We've been very fortunate that in recent years we've had huge advances in technology, but at this stage we can't do much with that profile,' Mr Sweeney said.

'The sample itself is not going to take the matter any further forward in 2012.

'It will take a significant breakthrough (in technology) ... which I believe will occur, that will allow us then to revisit the sample.'

Mr Sweeney estimated the new technology was 'five years plus' away from being developed.

'There is no expectation at this point in time that we have an imminent break but clearly this is an exciting time for law enforcement, (an) exciting time for forensic science,' he said.

The case was 'wedded to the psyche of everyone', including NSW police, he said.

'There have always been a number of suspects linked to the investigation.

'It is important to give confidence to the family members, give confidence to the community generally, that NSW police continues to look at unsolved crime, in particular unsolved homicides.'

Excerpt from:
DNA evidence found on beach victim