SNP treasurer Colin Beattie is stepping down from his role after he was arrested on Tuesday.
He said he will also step down from Holyrood’s Public Audit Committee while the police investigation into the party’s funding and finances takes place.
Mr Beattie, who has been SNP treasurer for most of the past 19 years, was arrested on Tuesday and spent around 11 hours in police custody before he was released without charge pending further investigation.
On 5 April, Nicola Sturgeon’s husband Peter Murrell, who recently stepped down as SNP chief executive, was also arrested as part of the investigation and was released after nearly 12 hours in custody without charge pending further investigation.
Mr Beattie said in a statement: “This afternoon I informed the party leader that I will be stepping back from my role as SNP National Treasurer with immediate effect.
“I have also informed the SNP Chief Whip at Holyrood that I will be stepping back from my role on the Public Audit Committee until the Police investigation has concluded.
“On a personal level, this decision has not been easy, but it is the right decision to avoid further distraction to the important work being led by Humza Yousaf to improve the SNP’s governance and transparency.
“I will continue to cooperate fully with Police Scotland’s enquiries and it would be inappropriate for me to comment any further on a live case.”
First Minister Humza Yousaf, who replaced Ms Sturgeon in March, said he wanted to “offer my thanks to Colin” after he announced he would step back as treasurer.
“I know that his decision to step back from the role of SNP National Treasurer will not have been an easy one, but he has done so in the best interest of the party,” he said.
“A new treasurer will be appointed as soon as possible.”
On Tuesday, he told Sky news Mr Beattie’s arrest was “not helpful” and “of course, I’m surprised when one of my colleagues is arrested”.
The police inquiry, named Operation Branchform, is looking into whether £666,953 of money raised since 2017 specifically for a second independence referendum has been improperly spent on other activities.
Police are also looking into a loan of £107,620 made in June 2021 by Mr Murrell, while he was chief executive.
It was launched in 2021 following seven complaints to Police Scotland but ramped up at the beginning of April with Mr Murrell’s arrest and the search of his and Ms Sturgeon’s Glasgow home.
Detectives also seized a £100,000 motorhome owned by the SNP from outside the home of one of Mr Murrell’s elderly relatives on 5 April, and searched the SNP’s Edinburgh offices at the same time.
Scotland’s deputy first minister Shona Robinson earlier told Sky News a “culture was allowed to develop” at SNP HQ
Ms Robison denied Ms Sturgeon had overall responsibility for the governance scandal – despite her being party leader for eight years.
She said the party needs to “get its house in order” to rebuild trust.
“There are clearly big issues for the party here,” Ms Robinson added.