• Almost two weeks later, SNP treasurer Colin Beattie was also arrested and released without charge while further inquiries were carried out.
• Mr Beattie resigned as party treasurer shortly afterwards.
Former First Minister Nicola Sturgeon has been arrested in connection with the ongoing investigation into the funding and finances of the SNP.
Police confirmed a 52-year-old woman was taken into custody as a suspect and is being questioned by detectives.
It follows the arrest and subsequent release of her husband, ex-SNP chief executive Peter Murrell, in April.
A spokeswoman for Ms Sturgeon confirmed she had attended a police interview by arrangement on Sunday.
The former SNP leader, who stood down in March, was then arrested and questioned by officers who have been investigating for the past two years what happened to more than £600,000 of donations given to the party by independence activists.
The spokeswoman said: "Nicola Sturgeon has today, Sunday 11 June, by arrangement with Police Scotland, attended an interview where she was to be arrested and questioned in relation to Operation Branchform.
"Nicola has consistently said she would cooperate with the investigation if asked and continues to do so."
Officers searched Ms Sturgeon's home and the SNP's headquarters in Edinburgh on 5 April, with Mr Murrell being arrested before later being released without charge pending further investigation.
A luxury motorhome which sells for about £110,000 was also seized by police from outside the home of Mr Murrell's mother in Dunfermline.
Almost two weeks later, SNP treasurer Colin Beattie was also arrested and released without charge while further inquiries were carried out.
Mr Beattie resigned as party treasurer shortly afterwards.
Ms Sturgeon, Mr Murrell and Mr Beattie were the three signatories on the SNP's accounts and the arrest of the former first minister had been widely expected - although there was no indication of when it was going to happen.
Under the Criminal Justice (Scotland) Act 2016, police can release a suspect for further investigation, but they can be re-arrested at a later date.
A spokesman for the SNP said the party would not comment on Ms Sturgeon's arrest, adding: "These issues are subject to a live police investigation."
Ms Sturgeon served as Scotland's first minister for more than eight years after succeeding Alex Salmond in the wake of the independence referendum in 2014.
She announced on 15 February that she would be standing down as both SNP leader and first minister once a successor was elected, with Humza Yousaf winning the contest to replace her.
Ms Sturgeon said at the time that she knew "in my head and in my heart" that it was the right time to go, and has denied the timing was influenced by the ongoing police investigation.
She was Scotland's the longest-serving first minister and the only woman to have held the position.
Scottish Conservative chairman Craig Hoy said the SNP was "engulfed in murkiness and chaos" and called on Mr Yousaf to suspend his predecessor from the party.
And Labour's shadow Scottish Secretary, Ian Murray, described the developments as "deeply concerning" and said the police inquiry must be allowed to proceed without interference.
Police Scotland launched their Operation Branchform investigation two years ago after complaints were made about what happened to £666,954 that was donated to the SNP by activists for a future independence referendum campaign
The party's accounts later accounts showed it had just under £97,000 in the bank at the end of 2019, and total net assets of about £272,000.
Last year it emerged Mr Murrell gave a loan of more than £100,000 to the SNP to help it out with a "cash flow" issue after the last election.
The SNP had repaid about half of the loan by October of that year, but still owes money to Mr Murrell - although it has not said how much.
Police Scotland has been looking into SNP funding for some time.
Ms Sturgeon is the third high-profile arrest. Her husband - Peter Murrell - was previously arrested and released without charge. So was the party's former treasury Colin Beattie.
This is a live case, so there's a limit to what journalists can report.
But politically, there's no doubt this is a big blow to Scotland's governing party.
The new leader - Humza Yousaf - had been trying to move on from arrests and police probes, to talk about policy and his vision for government.
It's inevitable he'll now face days of questions about this arrest and what it means for the party.