The man whose complaint triggered the investigation into the SNP’s finances has urged Scotland’s top police officer to explain why it is still running after almost three years.

Sean Clerkin said Police Scotland Chief Constable Jo Farrell should provide an update on Operation Branchform at a public meeting this week.

He said Ms Farrell had an ideal opportunity to clarify matters when she addressed the board of the Scottish Police Authority in Edinburgh on Thursday.

“We need to know which way the case is going and whether it’s going to proceed to prosecution or not. Three years is long enough,” he said.

“I think she has a duty to inform the Scottish public about the full range and depth and what exactly is being explored, because at the end of the day it’s taxpayers paying for this.

“The cost is now standing at £1.3million.

"For transparency and full accountability, there has to be a complete and comprehensive explanation of where Operation Branchform is and where it will go, and what the timelines are for making decisions. 

“We live in a democracy and there has to be accountability.”

There is a precedent for the Chief Constable to update the public on the investigation.

In July last year, the force’s then outgoing head Sir Iain Livingstone gave an interview in which he provided new information on the progress of Operation Branchform.

He told BBC Radio 4 that it had “moved beyond” the initial complaint to look at “potential embezzlement” and “misuse of funds”.

He also explained that it was a complex matter and that obtaining information “from banks and other financial institutions” involved seeking “judicial warrants”.

Mr Clerkin spoke to the Herald on Sunday ahead of the third anniversary of him reporting alleged fraud in relation to SNP fundraising.

On 26 March 2021, he lodged a complaint at Barrhead police station about some £660,000 raised by the SNP specifically for a second independence referendum, some of which appeared to have been spent on other things.

Within hours he was visited at home by two plain clothes detectives who took a statement.

Police Scotland launched a formal investigation into potential criminality in July 2021.

In April 2023, then SNP chief executive Peter Murrell, the husband of Nicola Sturgeon, was arrested and released without charge while officers raided SNP HQ in Edinburgh.

Officers also retrieved material from the couple’s home in Glasgow, erecting a blue evidence tent outside, and seized a £110,000 motorhome from outside the Fife home of Mr Murrell’s elderly mother.

Then SNP treasurer Colin Beattie and Ms Sturgeon, who quit as First Minister in February 2023, were arrested and released without charge in April and June 2023 respectively. 

Ms Sturgeon has said she is innocent of any wrongdoing.

There have been no reported arrests or charges since June 2023, leading to growing speculation and questions about the state of Operation Branchform and how long it will run.

Former SNP cabinet secretary Alex Neil recently said the final decision on whether or not to mount prosecutions should be taken away from the Crown Office and given to an independent legal figure from another jurisdiction to avoid any perception of bias.

The Lord Advocate, Dorothy Bain KC, who is both head of the prosecution service and the top legal adviser to the Scottish Government, has recused herself from any role in the case.

However Mr Neil said that was not enough, and the Crown Office should pass the final decision to someone else, as “justice has to be done and be seen to be done”. 

Mr Clerkin said he had been “sent to Coventry” by some fellow independence supporters since lodging the complaint and received a threat of violence.

However he was unrepentant, saying he acted to head off trouble for the Yes movement. 

He said he feared lingering controversy over the SNP’s finances could be exploited by the British state in the event of a second referendum or de facto referendum in an election.

“They would throw the dirty water a week or two weeks before. I had discussed it with colleagues and we agreed the best thing was to clean the stables out. 

“The British state is not stupid. They didn’t have an empire for nothing. They’re ruthless.

“They would do what was necessary to scupper an independence attempt by Scotland, and that would involve dirty linen influencing people a few weeks before a vote.”

Mr Neil backed Mr Clerkin’s call for a statement from the Chief Constable this week.

The former Health Secretary told the Herald on Sunday: “I realise that she can’t go into detail but I think she should give some indication of when it is likely that this inquiry will be completed one way or the other.

“Because there’s a real danger the police and the Crown Office will start to lose credibility if they don’t do something or make a decision soon about where this is going.

“Quite frankly it’s not fair to the people involved. It’s dragged on now for a long, long time. 

“Jo Farrell needs to reaffirm that it will be based on the timetable required to complete the inquiries and reach a conclusion and won’t be driven by any political considerations. 

“This week is an ideal opportunity for her to update not just the Scottish Police Authority, but more importantly the nation, because people are entitled to know what the score is.”

A Police Scotland spokesperson said: "As the investigation remains ongoing we are unable to comment."