The findings of an urgent review into police call handling in Scotland are expected to be published by the end of October.
The review was ordered by Justice Secretary Michael Matheson following the deaths of John Yuill and Lamara Bell in a car crash on the M9 in July.
It will be “thorough, evidence-based” and include visits to all Police Scotland call centres, Her Majesty’s Inspectorate of Constabulary in Scotland (HMICS) said.
The review will examine the “capacity and capability of the systems and the staff available in the control centres to manage, answer and prioritise calls” to the police.
Call handling has come under scrutiny after it emerged that police admitted the incident involving Mr Yuill and Ms Bell was reported to them but they failed to follow it up for 72 hours.
It was reported via a 101 call from a member of the public, but the message was not logged in the system and no action was taken at the time.
The pair were only discovered in the car three days later, on Wednesday July 8, after police received a further call to the scene.
Mr Yuill was found dead inside the blue Renault Clio. Ms Bell, who was discovered alive but critically ill, died in hospital a week on from the crash.
HM Inspector of Constabulary in Scotland Derek Penman said: “The aim of the review is to provide the Scottish Government and the Scottish Police Authority with an independent assessment of the operation, systems and procedures in place in call centres across Scotland.
“It will provide assurance on whether call handling is working effectively and efficiently within Police Scotland.
“It will examine the capacity and capability of the systems and the staff available in the control centres to manage, answer and prioritise calls.
“Staff training and the process to ensure that all calls are handled, recorded, dispatched and closed appropriately will also be reviewed.”
Mr Penman said the review will look at daily operational business in control rooms, and the wider change programme, which has seen the number of control rooms reduced.
It will audit calls on their journey through the centres and will include engagement with police officers and police staff, unions and staff associations, he said.
HMICS will set up a process to enable members of the public, police officers, police staff and others to offer relevant information.
Mr Penman added: “Information we receive this way will be treated in confidence and only for the purposes of this review.
“It will be used to identify potential strengths and weaknesses within contact, command and control (C3) centres and inform specific areas for our scrutiny.”
An interim report will be given to the Justice Secretary by the end of August, with the full report completed by the end of October.
HMICS will monitor progress in implementing any recommendations which come out of the review.