Detectives investigating the murder of missing Edinburgh woman, Suzanne Pilley, are basing a team in Argyll.
Four officers have been sent to Lochgilphead to follow up more than 80 calls over the movements of a silver car near the Rest and Be Thankful.
It is three weeks since the bookkeeper disappeared. The 38-year-old was last seen on CCTV outside her Thistle Street office on 4 May at 0855 BST.
Colleague David Gilroy, 47, has been questioned by police.
Det Ch Insp Gary Flannigan, of Lothian and Borders Police, who is leading the murder investigation, said the scale of the area and nature of the terrain meant officers had to take a very methodical, rational approach and they were yet to begin detailed searches.
He said: "We have had a hugely positive response from the public to all the appeals so far, and for that I am very grateful.
"We have not begun detailed searches in the area yet, but any searching will be co-ordinated around all the information available, which is heavily supplemented by sightings from the public.
"I don't need specific details about the car. I just need to know if people saw a silver-coloured family saloon in the area, around the specified times. I'm not asking people to supply details of a make or model, or even a registration plate.
"Wednesday 5 May is the day after the last Old Firm game and the day before the general election. I'm asking people in these areas to think back to what they were doing that Wednesday, and try to remember if they saw a silver-coloured car on a quiet stretch of country road."
Police are particularly keen to hear of any sightings on the small roads from Callander, Tyndrum and the Arygll Forest, and Lochgilphead to Inverary.
Ms Pilley, from the Stenhouse area of Edinburgh, is 5ft 4in, of slim build and has short, light brown hair.
She boarded the no 2 bus at Stevenson Drive at 0820 BST on Tuesday 4 May, getting off at 0832 BST and changing to the no 4 bus at Dalry Road, opposite Caledonian Terrace.
She got off the bus at Jenners department store in Princes Street at 0848 BST then went into the Sainsbury's supermarket near St Andrew Square, before heading to work in nearby Thistle Street.
On the day she went missing she was wearing a light-blue waterproof jacket, red fleece top, light-blue trousers or jeans, trainers and she was carrying a shoulder bag and a water bottle.
Efforts to trace Ms Pilley have included a huge screen positioned in St Andrew Square, which displayed CCTV footage of her on the way to her office.