A body believed to be that of Janet McKay, who suffered from dementia, was discovered in Clydebank yesterday, nine days after she was seen leaving her home in the Knightswood area of Glasgow.
The last reported sighting of her had been on CCTV leaving a bus in Clydebank on the day she went missing.
But Chief Superintendent Andy Bates, of Police Scotland, has now confirmed that a member of the public informed police last Friday of a possible sighting of Ms McKay, but that the information was not passed to call handling centres or to the inquiry team.
Officers have apologised to Ms McKay’s family and the issue has been referred to the Police Investigations and Review Commissioner (PIRC).
But speaking to BBC Scotland, Mrs McKay’s son, George McKay, said: “We’ve been very happy with the way the police have dealt with it - they’ve been very supportive to us.
“Any wider issues are a matter for Police Scotland but we have no criticisms to make of them.”
Justice Secretary Michael Matheson offered his condolences and said a thorough investigation would be carried out.
He said: “The Lord Advocate has immediately referred the matter to the Police Investigations and Review Commissioner (PIRC), as have Police Scotland, who will now be responsible for investigating the way in which Police Scotland have handled this particular missing persons inquiry.
“It’s important that we allow them to undertake that investigation, which will be directed by the Lord Advocate, who will ensure that there is a very thorough and timely investigation into this matter because that’s what the family deserve at the very least in order to get answers to how they conducted this particular inquiry.”
The incident follows a review of Police Scotland’s procedures launched after the deaths of John Yuill and Lamara Bell, who lay undiscovered for days despite a sighting of their crashed car off the M9 being reported to a police control room.
Scottish Labour’s justice spokesman, former senior police officer Graeme Pearson, said: “Coming so soon after the police failings around the M9 tragedy, it is very concerning that once again vital information from the public has not been passed on.
“The involvement of the Police Investigation and Review Commissioner is welcome, but any inquiry cannot be dragged out. The McKay family deserve to know as soon as possible exactly what went wrong, and the public then have a right to full transparency. The only way confidence can ever be restored in our police service is through an honest acknowledgement of what went wrong here.”
Lib Dem leader Willie Rennie added: “It is too early to tell what happened but we do need answers as there is a crisis of confidence in Police Scotland.
“Police officers and staff have been under extraordinary pressure since the centralisation of Police Scotland, the introduction of oppressive targets and stop and search, the closure of police stations to the public and the closure of control rooms. We need to establish whether there is a connection between these issues and this tragic case.”