Speaking at Holyrood, Ms Charteris suggested there could be “legitimate reasons” for delays, some of which have taken as long as a decade.

The recently completed FAI into the M9 crash took nine years. In 2019 a report found that the FAI system was plagued by “unexplained delays” that “have the potential to devalue the purpose” of the system. The HM Chief Inspector of Prosecution’s review of the FAI regime found that three years on from the last thematic report, there had been a “lack of progress in many areas” and that FAIs are characterised by “lengthy intervals of unexplained delays” and “periods of inactivity”.

SNP backbencher Fergus Ewing said that families waiting to hear if an FAI is to be held could be “fobbed off with explanations that appear to have come from the bumper book of excuses”.

He asked: “What faith can bereaved families have in the justice system when they have to wait in some cases for eight years before an FAI is actually held?”

Conservative justice spokesman Russell Findlay said that “families keep being failed by Scotland’s slow and ineffective system of investigating sudden, suspicious accidental and unexplained deaths”.

He compared the “few dozen FAIs” held in Scotland each year to the “tens of thousands of coroner’s inquests” which take place annually in England and Wales.

Ms Charteris said there were “often legitimate reasons for prolonged investigation”, but said that COPFS “has significantly reformed its processes in recent years to improve the quality of death investigations and reduce the time taken to investigate deaths and bring FAIs to court”.

She added: “In some cases FAIs have simply taken too long to commence and we appreciate and very much regret the impact which waiting for investigations to conclude has on families.

“I recognise that all families who have lost a loved one rightly expect investigations into the death to be progressed as expeditiously as possible.

“I offer my sincere apologies to those who have simply waited too long for FAI proceedings to commence. We want to do better.”