The body of a newborn boy found at a recycling centre is likely to have been collected from a household bin, according to detectives.
Cambridgeshire Police said the infant, named Gabriel by medical staff, was discovered at the site in Waterbeach on November 29.
Inquiries with recycling centre staff suggest it is "likely" the baby came from recycling collected from household blue bins in Peterborough and its surrounding villages, March, Whittlesey, Melbourn or streets off Mill Road in Cambridge, added the force.
A post-mortem examination carried out on December 5 returned inconclusive results about how Gabriel died.
Police have now obtained the baby's DNA, but are still trying to track down his mother.
In a statement, the force said: "Detectives have narrowed down the area that a baby boy found at a recycling centre may have come from as the investigation into his death continues.
"The newborn has since been ‘named’ Gabriel by medical staff due to his discovery at the centre, in Ely Road, Waterbeach, on 29 November, just before the start of advent.
"A post-mortem examination carried out earlier this month (5 December) returned inconclusive results about how he died. Police continue their efforts, together with partners, to get to the bottom of what happened to him."
Detective Chief Superintendent John Massey said police are "exploring every potential avenue".
He said: "We are still investigating this tragic incident and trying to locate the baby's mother to offer her all the support she needs.
"It is important to note that we have now obtained the baby boy's DNA, so we can compare this to any name that is put forward for a parent.
"We are particularly touched by the gesture of medical staff naming him Gabriel, given the start of advent, while we work together to try to identify him and his family.
"We are still keeping an open mind as to what has happened and are exploring every potential avenue, but if anyone has any information we would strongly urge them to contact us or Crimestoppers anonymously."
Anyone with information is urged to pass it to the force online here.