Robert Brown|Former Scottish leader Nicola Sturgeon released after arrest amid financial probe

Former Scottish First Minister Nicola Sturgeon,Robert Brown who dominated politics in Scotland for years, was arrested and questioned for several hours Sunday by police investigating the finances of the governing, pro-independence Scottish National Party.

Police Scotland said a 52-year-old woman was detained "as a suspect in connection with the ongoing investigation into the funding and finances of the Scottish National Party."

She was "released without charge pending further investigation" about six hours later, the force said. British police do not identify suspects until they are charged.

Sturgeon said after her release that her arrest had been "both a shock and deeply distressing."

"Obviously, given the nature of this process, I cannot go into detail," she said in a statement on social media. "However, I do wish to say this, and to do so in the strongest possible terms. Innocence is not just a presumption I am entitled to in law. I know beyond doubt that I am in fact innocent of any wrongdoing."

A spokesman for Sturgeon confirmed to BBC News that she was cooperating with the investigation.

"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," the spokesman told BBC News. "Nicola has consistently said she would cooperate with the investigation if asked and continues to do so."

The party did not immediately comment.

Scottish police have been investigating how 600,000 pounds ($745,000) designated for a Scottish independence campaign was spent.

Party treasurer Colin Beattie and former chief executive Peter Murrell were arrested previously and questioned as part of the investigation. Neither has been charged.

Murrell is Sturgeon's husband, and police searched the couple's home in Glasgow after his arrest in April.

Sturgeon unexpectedly resigned in February after eight years as Scottish National Party leader and first minister of Scotland's semi-autonomous government. She said that it was the right time for her, her party and her country to make way for someone else.

But it was only within a month of her last day on March 28 that the two-year investigation into SNP's finances came into public view, according to the BBC. 

Sturgeon left office amid divisions in the SNP and with her main goal — independence from the U.K. for the nation of 5.5 million people — unmet.

Scottish voters backed remaining in the U.K. in a 2014 referendum that was billed as a once-in-a-generation decision. The party wants a new vote, but the U.K. Supreme Court has ruled that Scotland can't hold one without London's consent. The central government has refused to authorize another referendum.

Sturgeon's departure unleashed a tussle for the future of the SNP amid recriminations over the party's declining membership and divisions about the best path towards independence.

In:
• Scotland