Police confirmed that a human head found in a quarry last month was male - and that the man might have died up to 50 years ago.
Officers from the Bedfordshire, Cambridgeshire and Hertfordshire Major Crime Unit (MCU) have been working with specialists from the Natural History Museum, and an odontologist, since the head was discovered on May 16.
Following numerous tests and examinations, specialists believe the man was aged between 30 and 50 at the time of his death, which could have been as long ago as the 1960s. However experts believe it is more likely to have occurred about 10 years ago.
Detective Inspector Jerry Waite, from the MCU, said: “One possible scenario we are looking at is that it may have been a tragic accident whereby the man was hit by a train along the Bedfordshire line.
“We believe the head may have been lodged somewhere along the structure of the bridge in Sharnbrook, and as part of the recent cleaning process, has been dislodged, found its way into the skip and deposited at the quarry in Mepal.
“We have been working very closely with anthropologists at the Natural History Museum in London to establish the age and gender of the deceased, as well as the National Crime Agency’s Missing Persons Database, which unfortunately has not shown any DNA matches.
“I would urge anyone who has any suspicions around who this person may be to contact us.”
When the head was discovered it was initially suspected that it might be that of missing Milton Keynes woman Natalie Hemming. However this was subsequently ruled and her body was found in woodland in Hertfordshire.
Anyone with information regarding the head is asked to contact the Major Crime Unit on 101 or Crimestoppers, anonymously, on 0800 555 111, or via their online reporting system at www.crimestoppers-uk.org.