Statement from Willie Rennie MSP, leader of the Scottish Liberal Democrats, on the M9 crash:
"I am deeply sorry that John Yuill and Lamara Bell have been failed. My sympathy is with the family and friends of John and Lamara.
"I have been contacted by constituents and serving police officers who are horrified by this tragedy. They want a thorough investigation into the serious issues raised by the case and whether they are connected to the wider problems with the operation of Police Scotland.
"Everyone agrees that a three day delay between the initial call to the control room and finding the couple is unacceptable and we need to establish why this happened.
"I know police offers have been deeply affected by this case. There is great upset within the force.
"It is of such importance that serious questions must be answered.
"It is right that the Police Investigations and Review Commissioner (PIRC) is investigating the matter but that may not be enough. A wider independent investigation may be required.
"I want the Justice Secretary to review whether an investigation by the PIRC is sufficient. The operation of Police Scotland is under scrutiny here and we need an investigation to match its serious nature."