Police searching a cemetery for missing teenager Jayden Parkinson have revealed there is "evidence of recent and unauthorised disturbance" at a grave.
Thames Valley Police said the hunt for the 17-year-old had led them to the Great Western Cemetery next to All Saints' Church in Didcot, Oxfordshire.
Jayden disappeared on December 3 after she was last seen leaving the town's railway station at about 4.30pm.
Detective Chief Superintendent Andy Murray, who is leading the investigation, said police had received "significant and highly relevant information" which led their search efforts to a specific grave.
"This morning we have started the difficult process of securing evidence from a gravesite," Mr Murray told reporters from the scene.
"That process is primarily conducted by forensic scientists. They are meticulous, they are methodical and therefore it will take some time.
"We will be here all day, all evening and, if necessary, all night until that process is complete.
"We are at an established grave but there is evidence of recent and unauthorised disturbance at that grave.
"I would like to emphasise that we have informed the family associated with that grave, as well as families associated with gravestones in the surrounding area.
"We would like to keep the disruption to a minimum. We are trying to make sure that this church stays open and as such there is a large funeral here today and we will afford that funeral the respect and dignity that it deserves.
"We are in constant contact with Jayden's family and they will be the first to know if we have any news."
There was a large police presence at the church, with forensic teams unloading equipment from vehicles and carrying it into the cemetery.
Police also erected a large screen around the blue tent covering the grave to allow experts to work without being seen by the public walking along nearby footpaths.
Jayden's former boyfriend, 22-year-old Ben Blakeley, of Christchurch Road, Reading, Berkshire, appeared at Oxford Crown Court yesterday charged with her murder and perverting the course of justice by disposing of her body and lying to the police about the last time he saw her alive.
A 17-year-old boy, who cannot be named for legal reasons, appeared at Oxford Magistrates' Court charged with perverting the course of justice between December 3 and December 10 by assisting in the disposal of Jayden's body and other evidence.
More than 100 uniformed officers and detectives are working on the case, backed up by specialists from the National Crime Agency.
Mr Murray said yesterday that there was "no indication" that Jayden was alive and appealed to people to get in touch if they remembered seeing the teenager "on her own, or in the company of anybody".
He also repeated an appeal for any information about a man seen struggling with a suitcase just outside the village of Upton, near Didcot, at about 2am on Monday December 9.
The same man was later seen with the same suitcase in the Lydalls Road area of Didcot - where All Saints' is located - at about 3.30am.
Detectives have since recovered several suitcases, one of which "may well be significant", Mr Murray said.
All Saints' Church said in a statement posted on its website: "We at All Saints' Church are co-operating with the police in their inquiries in every possible way at this time.
"We are praying for Jayden's family and friends at this very distressing time."
Police have also sealed off a semi-detached house in Great Western Drive, which is a few hundred yards from the cemetery where police are searching for Jayden.
A park which links Great Western Drive to an alleyway running behind the cemetery has also been cordoned off.
Forensic officers are examining the park and Great Western Drive.