The UK and Scottish parliaments should hold a joint inquiry into Peter Murrell's financial crimes, former Labour first minister Jack McConnell has said.
Murrell, the ex-SNP chief executive and estranged husband of Nicola Sturgeon, pleaded guilty last week to embezzling more than £400,000 from the party over 12 years.
Lord McConnell called for Westminster's Public Accounts Committee and Holyrood's Public Audit Committee to look into the scandal together.
It came after Sturgeon, speaking to the BBC's Sunday with Laura Kuenssberg, denied covering up problems in the party's finances or having any knowledge or Murrell's wrongdoing.
McConnell, who was first minister from 2001 until 2007, told BBC Radio Scotland Breakfast he "would like to see the two parliaments coming together" to investigate the embezzlement.
The peer said a standalone Holyrood inquiry might be seen as presiding over a "cover up", while a Westminster one might be perceived as carrying out "a hatchet job" on the SNP.
Lord McConnell said a joint probe should look into whether the relationship between Scotland's prosecution service – the Crown Office and Procurator Fiscal Service (COPFS) – and politicians in the Scottish government had become too close.
He also said it should examine whether public funds provided to the SNP at Westminster were involved in the embezzlement and whether safeguards should be introduced for small donors to political parties and movements.
"Let's get to the bottom of this and let's ensure that political parties and political movements in the future and perhaps also the governance of Scotland in relation to the legal system are protected in the interests of the public," he said.
Opposition MSPs raised concerns about the role of Scotland's top law officer, Lord Advocate Dorothy Bain, after it emerged she told First Minister John Swinney details about Murrell's charge almost a year before they became public.
Bain - who has a dual role as head of the prosecution service and the government's chief legal adviser - defended her conduct, saying she had no role in the prosecution and that the disclosure to Swinney was standard practice in high-profile cases.
It is not clear how a joint inquiry would work in practice as there has never been one in the 27 years since the devolved Scottish Parliament opened.
There have also been calls for separate Holyrood and Westminster inquiries.
First Minister John Swinney has previously rejected calls for any parliamentary inquiry, arguing that his party has improved its governance and oversight, and that an inquiry would add nothing to a lengthy and detailed police investigation.
He has also denied that any public funds from the UK Parliament were involved in the embezzlement, and stressed that the prosecution service acts independently of government.
Lord McConnell said Swinney's opposition to an inquiry was a "big mistake", accusing the SNP leadership of "digging their heels in".
He urged Swinney to "reflect" that a joint inquiry could be in the public interest and perhaps in the party interest too.
Critics have accused Swinney and Sturgeon of shutting down concerns about SNP finances.
They point to the resignation in 2021 of senior party officials - including former treasurer Douglas Chapman - who say they were not given access to key documents.
Ex-MP Joanna Cherry, who also quit the SNP ruling body in 2021 due to a lack of transparency, has recently claimed concerns were not listened to by party leaders.
Sturgeon told the BBC's Sunday with Laura Kuenssberg: "I reject completely the notion that people were trying to alert the party to the kind of behaviour that Peter pled guilty to on Monday."
Swinney said last week that he was not "not conscious" of having shut down concerns about party finances.
Rejecting calls for a Holyrood inquiry, he said "we know exactly what happened" in the Murrell case.
The first minister told the BBC: "You can't actually get a standard of investigation any higher in Scotland than a forensic police investigation that results in a successful high court prosecution and a guilty plea."
There is not expected to be an announcement on whether the Public Accounts Committee will launch an inquiry for at least a week.
Sturgeon was arrested and released without charge in 2023 as part of the police probe into SNP finances. She was told last year that she was no longer under investigation.
The former first minister, who was jointly responsible for approving SNP accounts during her eight years in charge of the party, told the BBC: "The idea there was anything in the accounts that would have alerted me to what Peter pleaded guilty to is absolutely fundamentally untrue.
"If there had been, I suspect the police and the Crown Office might have reached a different position on me."
The former first minister announced last year that her marriage was Murrell was ending after almost 15 years.
Murrell is due to be sentenced later this month.
Responding to McConnell, a COPFS spokesperson said: "Professional prosecutors from COPFS and independent counsel dealt with this case without involving the lord advocate or solicitor general. All Scotland's prosecutors operate independently of political influence.
"Communications from the lord advocate's office to the office of the first minister's office have been explained to the Scottish Parliament."
