It is a shocking murder mystery which has kept a community wondering for more than 40 years.

Eastern Daily Press: The pink nightdress worn by a woman whose headless body was found at Cockley Cley in 1974The pink nightdress worn by a woman whose headless body was found at Cockley Cley in 1974

Now detectives believe new DNA evidence could help to uncover the killer as they look to finally shut the file on the gruesome cold case.

Detectives investigating the case have confirmed the victim, found headless at Cockley Cley, was probably a mother and is thought to be aged between 23 and 35.

The body was found, wearing only a pink Marks and Spencer night-dress, on heath land off Swaffham Road in Cockley Cley, near Swaffham, on August 27 1974.

DCI Andy Guy, from Norfolk and Suffolk's Major Investigation Team, said tests on her remains had revealed the woman, whose identity remains a mystery, had probably given birth to a child or children.

Eastern Daily Press: Det. Supt. Ivan Mead holding the dustsheet with the 'N.C.R' crest about which Norfolk POlice were seeking information, in relation to the Cockley Cley Headless Body, 1974staff pic R.J. 10/09/74Det. Supt. Ivan Mead holding the dustsheet with the 'N.C.R' crest about which Norfolk POlice were seeking information, in relation to the Cockley Cley Headless Body, 1974staff pic R.J. 10/09/74

He said: 'With the advances we have made in recent years in science and technology, we are now able to look at the case in more microscopic detail and as a consequence of the work carried out so far we now have her full DNA profile.

'The second post mortem examination also showed her pelvic girdle had widened which is a bodily change in expectant mothers to allow childbirth to take place.

'It is absolutely possible we could use the DNA recovered to link the woman to a living family member which could provide the breakthrough in the case. I believe if we identify the victim we can identify her murderer.'

He added: 'Other examinations showed the cover, used to conceal her body, was marked with NCR. This is a logo for National Cash Registers and was, as we later found out, quite a rare cover. In addition, the rope used to tie the victim up was unusual as it contained an non-standard make up which would indicate a particular use. Further enquiries revealed this type of rope was predominantly used in agricultural businesses.'

Eastern Daily Press: Police pic showing Swaffham cemetery, where they exhumed the body of the headless woman that was found in Cockley Cley in 1974Police pic showing Swaffham cemetery, where they exhumed the body of the headless woman that was found in Cockley Cley in 1974

The victim had been bound and concealed under the dust sheet. The first post-mortem examination, conducted the same day, suggested she was in her 20s or 30s and about 5ft 2ins tall.

Despite inquiries and nationwide appeals in the year after the discovery, neither the woman nor her killer were ever identified.

The first murder inquiry ran from 1974 to 1975 before the case was left open on police files.

A total of 15,000 people were spoken to, 700 statements taken and 6,750 house to house questionnaires completed.

Eastern Daily Press: Swaffham cemetery where the woman was later buried.Swaffham cemetery where the woman was later buried.

In 2011, over 580 missing woman were traced as part of a further enquiry into her death and of those 580, over 540 were identified with 263 women found alive and well, 52 women traced as dead and 41 women eliminated through DNA profiles taken from their family members.

DCI Guy said: 'The task of finding someone who has decided not to be found should not be under estimated, this often presents ethical dilemmas as the missing person may not want the family to know where she is.

'However, one important line of enquiry remains unresolved. As part of our investigations we employed two scientists to study the victim's isotopic make up. This resulted in both experts believing that the victim had spent time in an area defined central Europe this would encompass Denmark, Germany, Austria and northern Italy.

'Another interesting feature was her diet appeared to be predominately fish/shellfish. This led us to one report of a woman known as 'The Duchess', who lived and worked around Yarmouth docks and was thought to be from Denmark. She was known to people in the Great Yarmouth area around 1973/74 but one day just disappeared. It may be that 'The Duchess' has nothing to do with this enquiry but we would very much like to be able to eliminate her as the victim at Cockley Cley as we have been unable to establish her true identity.

'If anyone does have any knowledge of who the 'The Duchess' may have been or has any information about the victim at Cockley Cley we would be very pleased to speak to them in confidence if necessary. I believe the victim was murdered in the first or second week of August 1974, so I would ask members of the public, is there a female relative, friend, neighbour or colleague who disappeared about this time and has not been seen since? This would apply even if you reported her missing to the police at the time.'

•Anyone with information to the case or believes they have may know the victim should contact the investigation team on 01953 424520.