A woman who survived a fatal fire at a Scottish luxury hotel has said she "cannot fathom" why it took three years for the case to get to court.
Hannah Munns said that not knowing the cause of the blaze at Cameron House had "played with my mental health".
It has emerged that the cause was known just five months after the fire in December 2017, which killed two men.
But the survivors did not know the full details until they emerged in court in December 2020.
The fire was started after a night porter placed a plastic bag of ashes in the concierge cupboard.
Simon Midgley and his partner Richard Dyson died when the blaze ripped through the five-star hotel on the shores of Loch Lomond.
Andrew Wade, an independent forensic scientist who specialises in fires and explosions, was asked by Police Scotland in May 2018 to investigate what happened at Cameron House.
He told the BBC that the investigation was "relatively straightforward".
Mr Wade viewed CCTV footage showing the night porter placing a bag of ash in the cupboard, then visited the site to thoroughly examine the physical evidence.
The investigator said the ground floor of the hotel was relatively undamaged with the exception of the concierge cupboard.
"You have to, in a way, ignore what you saw on the CCTV, establish where the fire started and then look at the possible causes," he said.
"At that stage the two halves come together and say all the physical evidence confirms what we can see on the CCTV.
"So at that stage I was satisfied that we were dealing with a smouldering fire from the hot embers which were put in the cupboard there."
Mr Wade submitted his preliminary report on 13 May 2018.
It took a further two years and seven months until the case came to court and the families of the men who died and the survivors found out the full details of what happened.
The Crown Office said subsequent reports covered a wider range of matters and led to criminal proceedings. Covid also had an impact on timings.
The hotel was fined £500,000 after admitting breaches of fire safety rules, while porter Christopher O'Malley was given a community payback order for breaching the Health and Safety at Work Act.
Ms Munns and her family had been staying on the same floor as the men who died.
She told the BBC that the time it took to get the case to court "beggars belief".
"It's really hard to articulate or understand if you haven't been through it, but not knowing what caused it, what the danger was, has really played with my mental health," she said.
"I can't fathom how it's taken so long to get to court and the amount of pain people have been through, not just me.
"I speak to Jane, Simon's mum, and she has been through absolute hell trying to understand what happened and why her son's not coming home.
"I can't imagine there is a situation where someone could tell me a reason why it has taken so long and for it to be acceptable."
Ms Munns is calling for a fatal accident inquiry (FAI) to be held into the fire. A decision on whether to hold an inquiry is expected later this month.
A spokesperson for the Crown Office and Procurator Fiscal Service said: "COPFS appreciates the impact the time taken to conclude investigations can have on those involved and we are committed to resolving them as soon as we can.
"We maintained regular contact with the nearest relatives of Simon Midgley and Richard Dyson and are satisfied that our communications were appropriate having regard to the welfare and wishes of those involved.
"The convictions and sentences in this case were the culmination of a thorough and technical investigation carried out by Scottish Fire and Rescue Service, West Dunbartonshire Council and Police Scotland, overseen by the health and safety investigation unit of COPFS."