Soil found on boots owned by murder accused Ross Willox was a 92% match for mud at the spot where Emma Faulds' body was found, a court has heard.
Police focused their search for Ms Faulds in Glentrool Forest, Dumfriesshire, after a soil expert examined potential evidence.
This included Timberland boots owned by Mr Willox, 41, as well as two vehicles.
Mr Willox denies murdering Ms Faulds at his home in Monkton, South Ayrshire, on 28 April 2019.
The 39-year-old's remains were discovered in Glentrool on 12 June.
The High Court in Glasgow heard Prof Lorna Dawson was an expert adviser who had worked with police forces across the UK and in Australia.
She was asked to examine Mr Willox's boots as well as a Mercedes and Jaguar for the presence of soil.
Prof Dawson told jurors that soil recovered from the Timberland boots was far more likely to have come from the specific Glentrool site "rather than a similar common bog habitat.".
She stated that there was "very strong to extremely strong" support for the findings.
The court heard there was a 92% soil match from the shoes compared to the soil that covered Ms Faulds' body.
A further possible match from the forest site was found under the wheel arch of a Jaguar car.
Ms Faulds was left in a forest area where someone "would not normally walk through", a court has heard.
'Wet and boggy'
Prof Dawson said Ms Faulds was left in a forest area where someone "would not normally walk through".
The court heard police found the body after concentrating on areas that were "wet and boggy" in Glentrool.
Prosecutor Pau Kearney asked Prof Dawson: "Police were searching in the general area at the time you provided the information. They then altered the search more to this type of environment there?"
She replied: "Near to an area that would create this boggy environment."
The body of Ms Faulds, of Kilmarnock, East Ayrshire, was found on 12 June before the professor visited the site.
The court heard there was a "strategy meeting" on how best to take soil and plant samples from the scene to compare with earlier findings.
Mr Kearney asked the professor what the area was like.
She said: "There was no walking path there...nothing of a natural path.
"It was quite difficult circumstances to work under due to the amount of midges.
"It was not an area that you would naturally walk through. You would avoid it."
Mr Willox denies the charges against him.
The trial, before judge Lord Mulholland, continues.