Sarah Everard, 33, vanished while walking home from a friend's apartment in London on March 3.
UK police investigating a young woman's disappearance discovered what they think are "human remains" in woodland in Kent on Wednesday.
It comes after a serving UK police officer was arrested on suspicion of murder following the disappearance of the 33-year-old woman in London a week ago.
Sarah Everard vanished while walking home from a friend's apartment in London on March 3.
A man in his 40s was arrested on suspicion of kidnap on Tuesday evening in relation to her disappearance, London's Metropolitan Police said.
The force said he had been arrested on suspicion of murder and a separate allegation of indecent exposure.
Metropolitan Police Commissioner Cressida Dick said on Wednesday the fact that the man is a serving police officer "sent waves of shock and anger through the public and through the whole of the Met."
Police said on Wednesday evening that they found human remains in an area of woodland in Ashford, Kent.
"As you can imagine, at this early stage we are not able to confirm any identity and indeed this may take us some time," Commissioner Dick said.
The last known contact with Everard was a phone call with her partner, organising plans for the following day, while she was making a 50-minute walk to her home in Brixton from Clapham.
Police are studying CCTV, doorbell footage and phone analysis to work out the exact route she took, and are asking residents & delivery drivers in the area to check any doorbell or dash-cam footage from the night.
The officer was not on duty at the time of Everard's disappearance.
The force said he was arrested along with a woman who has been held on suspicion of assisting an offender.
"This is a serious and significant development in our search for Sarah and the fact that the man who has been arrested is a serving Metropolitan Police officer is both shocking and deeply disturbing," the Met Police's assistant commissioner, Nick Ephgrave, told reporters.
A cordon has been put up outside a block of flats in Clapham, near where she was last seen and sniffer dogs have been used to search areas nearby.
"We have seen an overwhelming response from the public and I repeat my request for anyone with information that may be relevant to come forward, no matter how insignificant it may seem," Detective Chief Inspector Katherine Goodwin said in a statement.