A detective investigating the savage murder of a young woman more than 40 years ago has said he believes her identity is key to discovering the killer.

Back in August 1974 a farm worker discovered the beheaded body of a petite woman in a field at Cockley Cley, near Swaffham, dressed in only a Marks and Spencers night-dress.

Detective Chief Inspector Andy Guy is heading up the investigation by the Norfolk and Suffolk Major Investigation Team into the death after the body was exhumed in 2007 to allow DNA evidence to be gathered.

Now, after the investigation has tracked down more than 580 missing women, DCI Guy thinks finding out who she was will lead to her murderer.

He said: 'Why has she been beheaded? The main reason would be to hide her identity.'

DCI Guy believes the killer is likely to be known to the victim. He said: 'What do we know? She was wearing a night-dress so there is some suggestion of her being comfortable with the person.'

DCI Guy added that a number of police forces from overseas had been in touch with missing women who could be the victim.

'Sometimes we get calls from other police forces,' he said. 'Sometimes we get calls from members of the public, other times from people who are trying to help out by speculative work.'

The case was of national interest at the time due to its macabre nature and has since remained in the public consciousness. DCI Guy said the force have been contacted with people suggesting various famous serial killers.

'It is very easy to go off on a tangent,' he said. 'We have looked at people of interest nationally who have connections to Norfolk.'

He added his team had used data compiled by other forces when investigating possible victims of Fred West and Peter Tobin as they included many missing women.

While advances in technology have seen DNA become a vital part of the detective's tool kit this was not the case in 1974 and it means officers have to track down living family members of missing women to compare their DNA against the victims.

DCI Guy said: 'We have knocked on lots of doors to ask for DNA and of course we have to explain why we are there. Telling someone a family member could have been a body found in a field is a real hand-grenade to throw into people's lives and there are other ethical dilemmas as well.'

Anyone who has information about the murder or who remembers a family member, friend, colleague or neighbour who disappeared around August 1974 should contact the Norfolk and Suffolk Major Investigations Team on 01953 424520 even if they were reported missing at the time.