The man who called police to report a car crash which the force did not investigate for three days has said he feels guilty he did not follow it up after both people in the vehicle died.
Lamara Bell, 25, was critically injured in the crash off the M9 near Stirling on Sunday July 5 and died in hospital yesterday, while her partner, John Yuill, 28, died at the scene.
They were only found in the car on Wednesday, around 72 hours after the accident, despite the incident being reported to police on the day it happened.
Police Scotland Chief Constable Sir Stephen House has said he will not resign over the matter.
The man who initially reported the crash last Sunday told the BBC the officer he spoke to was not dismissive and sounded as though he knew what he was doing.
Details were taken of the location, which the caller described as "on the fork, between the M9 and M80".
The man, who wants to remain anonymous, told the BBC there was "nothing to suggest they would not take it seriously" and that he "assumed the police would check it out".
He became concerned on the Monday and Tuesday when the car was still there with no police tape covering it, but thought it "must be awaiting recovery".
He said he was "aware of what was being said about whether he should have done more" but believed police were handling it.
Sir Stephen has said he believes it is right for him to stay in the job and provide leadership at Police Scotland despite the incident.
He said: "In anything like this I consider my position. I think you would be inhuman if you didn't. You see what's happened over the last week and think about that, and I certainly have.
"I believe the right thing to do is to stay to get through this process, to get through this tragic event and the series of events that followed it and to see what can be done to fix the situation.
"I don't want anyone out there thinking I'm the type of person that says 'I'll never go, I'll have to be forced out'.
"If I come to the conclusion that I should resign then I will resign. I don't believe that's the case at this moment in time.
"This organisation needs leadership, I'm providing that leadership."
Sir Stephen last week apologised to the relatives of the two crash victims and admitted police ''failed both families''.
Scottish Justice Secretary Michael Matheson has ordered Her Majesty's Inspectorate of Constabulary in Scotland (HMICS) to undertake an urgent review of all police call handling.
The case is also subject to an independent probe by the police investigations and review commissioner (Pirc).
Asked whether he still has full confidence in Sir Stephen, Mr Matheson told BBC Radio Scotland: "Yes, he still has my confidence" and added that there was no indication of any ''systemic failure'' in the police call handling process.
First Minister Nicola Sturgeon also told the channel that the police chief has her "confidence" and "backing".
But Scottish Labour justice spokeswoman Elaine Murray said earlier that Sir Stephen should be considering his position.
The couple were reported missing after visiting Loch Earn, Stirlingshire, in a blue Renault Clio.
Police say a member of the public contacted Police Scotland at around 11.30am on Sunday July 5 to report they could see the vehicle down an embankment near the M9 slip road at Bannockburn.
The call was answered, but ''for reasons yet to be established'' it was not entered on to the police systems and no action was taken at the time.
The car was found when officers were called to the scene by another member of the public on Wednesday.
Meanwhile, Ms Bell's brother Martin has posted his thanks on Facebook to the community in Falkirk.
He wrote: "I'm blown away by the effort and time our community in Falkirk are putting into making the loss of my sister as painless as possible for my family."