Police probing the "tragic" deaths of a mother and her two daughters in a crash have held a roadside check a week on in the hope of finding new information.
Grampian Police spent two hours speaking to motorists
Ann Copeland, 45, and her daughters Ciara, seven, and Niamh, 10, died in the A92 crash in Aberdeenshire.
It has been established some form of spilled lubricating oil was on the road and could have been a factor. Police fear the vehicle may still be leaking.
Grampian Police stopped motorists between 0730 GMT and 0930 GMT.
The family, who were travelling in a Citroen Saxo apparently on the way to school, were from the coastal village of Johnshaven.
The accident happened on a double bend, said locally to be an accident black spot.
Police were asking motorists on Wednesday morning if they were on the road and if they saw any vehicle leaving a deposit on the road.
Grampian Police said that the substance found on the road was oil-based.
It was some form of lubricating oil from a vehicle, possibly hydraulic fluid, gearbox fluid, or engine oil. The substance was not diesel.
Insp Ian Kirkwood said that the fluid, which covered several yards of the roadway at the scene, could prove to be a significant factor in the circumstances surrounding the collision.
Ann Copeland and her two daughters were killed
He said: "We are trying to establish the source of the fluid and are following a number of lines of enquiry.
"We are anxious to trace the vehicle involved in case it is faulty as we would want to stop the same thing happening again.
"We are appealing to garages which may have had a vehicle in for repair say to a gearbox or engine and which had lost similar fluid to contact us."
Insp Kirkwood said of the roadside check: "We have had a good response from the public to our appeals for anyone who was on the road around that time to contact us.
"However, there may be a number of people who are unaware of our appeal or have not contacted us for whatever reason.
"They may well have seen something which could help us establish the cause of this terrible collision."
Anyone with information is asked to contact Grampian Police on 0845 600 5700.