The 53-year-old’s body was found with “significant head injuries” just “a few hundred yards from her house” in Akholt Wood, Snowdown, near Dover, on Tuesday.
Police said she died from blunt trauma to the head, but would not comment on any potential murder weapon.
At a news conference in nearby Aylesham, on Friday, Kent Police assistant chief constable Tom Richards urged people to be “cautious, vigilant, aware of their surroundings”.
He said he was not specifically advising women, or anyone, to stay at home or to avoid any particular locations.
“I do understand that local residents are concerned, that’s completely natural,” he said, adding that Ms James’s murder was “an incredibly rare and isolated incident”.
Hundreds of officers are involved in the investigation and searches for evidence in the area continued on Friday.
Mr Richards said police did not at this stage “have any identified suspects”.
“We are keeping all options open to us while we fully investigate the circumstances of this matter and try to understand fully what happened,” he said.
“We do not at this stage understand the motive.”
He declined to say whether detectives had found signs of a struggle.
Ms James, who had served with the force since 2008, was not on duty or in uniform and had been walking her dog at the time of her death.
Her dog was found unharmed at the scene when police arrived and there was “no evidence that any of her possessions were missing”.
The death was originally viewed as “suspicious”, but Kent Police confirmed on Wednesday afternoon that it was being treated as murder.
Ms James was a “hugely devoted, passionate” person who was “completely committed to serving the people of Kent”, where she had recently worked with victims of domestic violence, Mr Richards said.
He said her colleagues were “very shocked, very upset”, and were receiving support.
Police said Ms James’s family were being supported by specialists officers at this “incredibly difficult and challenging” time.
Ms James’s nephew, Karl James, said his aunt was “just a lovely person” and her death has been “a real shock”.
“Obviously it’s been a real shock. I work away, but my wife is here – heavily pregnant – and with young kids, so she’s on edge at the moment too,” he told 5 News.
“So I’ve come home and just waiting for answers – that’s the worst bit really.”
Floral tributes have been left for Ms James in Aylesham.
Officers have appealed for anyone who may have seen something unusual or suspicious in the area on Tuesday or Wednesday to come forward.
They are encouraged to contact Kent Police on 0800 0514 526.