Nicola Sturgeon will face calls this week to trigger a major overhaul of a fatal inquiry system blamed for causing distress to those affected by tragedy.
Orkney Lib Dem MSP Liam McArthur will use a Holyrood debate on Thursday to raise cases including the Super Puma crash near Sumburgh in 2013 and the death of a sailor off Jura 10 years ago.
Mr McArthur will repeat demands for the Crown Office to lose control of inquiries and try to gain support for a new system of checks and balances.
He also wants to split the role of the Lord Advocate, Scotland’s top prosecutor, who is also a member of the government.
Mr McArthur said: “It took more than seven years for the investigation into the 2013 Sumburgh helicopter tragedy to conclude.
“When delays like that happen memories fade and lessons become more difficult to learn. That’s just one example of why the system needs to change.”
He added: “The current set-up in the Crown Office isn’t working. There needs to be a full and frank conversation about its reform.
“The Fatal Accident Inquiry system is grotesquely complex. It is utterly incapable of delivering timely justice. Too often it adds to the misery for the families of those involved.
“We need change so that those affected by tragedy get swifter closure, and lessons are learned.
“The system is in desperate need of reform. Scottish Liberal Democrat research found evidence of a huge backlog, with families still waiting up to a decade to see answers.
“It is difficult to imagine the pain and frustration that loved ones must feel when such tragedy is followed by stagnant and silent investigations.
“But these delays also pose a danger to public safety.
“Without learning lessons, tragedies might be repeated.
“There’s no more time for tinkering round the edges on this.
“We need a commitment to a fundamental overhaul.”
The Lib Dems highlighted the inquiry into the death of Stanislaw Bania in the Clyde in 2012, which concluded in August last year.
They also pointed to the inquiry into the death of a sailor off the west coast which took a decade since the accident.
Boguslaw Kopec died on March 13 in 2011 but an investigation only concluded 10 years later.
The 46-year-old, from Poland, was crushed to death against a railing when a rope tightened.
Mr Kopec had been working on the Forth Guardsman vessel between Islay and Jura.
The inquiry found the death could have been avoided if a “stopper” had been in place to stop mooring lines and ropes moving.
In March this year, Sheriff Frances McCartney criticised the “significant delay” which affected the family and availability of evidence.
The length of time taken to probe a helicopter crash was sharply criticised by a sheriff last year.
Four offshore workers died when a Super Puma carrying 18 people plunged into the sea off Shetland on August 23, 2013.
Sarah Darnley, 45, from Elgin, Gary McCrossan, 59, from Inverness, Duncan Munro, 46, from Bishop Auckland and George Allison, 57, from Winchester, died.
Families, survivors and unions campaigned for an inquiry which took seven years to bring to court.
At a preliminary hearing in Aberdeen, Sheriff Principal Derek Pyle said the time delay was like “wading through treacle”.
In a statement, the Crown Office and Procurator Fiscal Service said: “We have modernised our processes to reduce the time taken to investigate deaths and bring Fatal Accident Inquiries to court.
“Despite a significant increase in the number of deaths reported to the Procurator Fiscal in the last year, less than 2% of the total ongoing fatalities investigations are over two years old.”