The police force said it would send a report to Scottish prosecutors and that officers searched a number of locations as part of the probe.
The husband of Scotland's former first minister Nicola Sturgeon has been arrested as part of an ongoing police investigation into allegations of missing money.
Peter Murrell, 58, served as the CEO of the Scottish National Party for more than two decades but announced his resignation a few days amid a scandal, ahead of his wife's last day in office in March.
The home the couple share in Glasgow was sealed off by police, with an evidence tent erected in the front garden.
In a Wednesday night update, Police Scotland said the man arrested in the morning was questioned by detectives and “released without charge pending further investigation.” The police force said it would send a report to Scottish prosecutors and that officers searched a number of locations as part of the probe.
A spokesperson for Sturgeon, 52, said in a statement to the BBC and British TV channel Sky News that she had “no prior knowledge of Police Scotland’s action or intentions” when Murrell was arrested. She plans to cooperate with police if she is asked, the spokesperson said.
Police Scotland have been investigating allegations that £600,000 (€680,000) of party money was misused during his time as chief executive of the party.
Officers are also searching other addresses, including it is understood the SNP's Edinburgh headquarters.
“Clearly it would not be appropriate to comment on any live police investigation but the SNP have been cooperating fully with this investigation and will continue to do so," the party said in a statement released after the arrest.
In a statement, the opposition Scottish Conservatives said Sturgeon and her successor Humza Yousaf "must cooperate must cooperate fully with the investigation into this very serious case and commit to openness and transparency."
“While there is an ongoing police investigation into the SNP’s finances, and given that a suspect has now been arrested, it is right that due process is followed and any potential wrongdoing investigated thoroughly by the police," said shadow constitution secretary Donald Cameron.
Why did Peter Murrell resign from his role?
Until mid-March, Peter Murrell resigned after it became clear he had provided false membership numbers to the party's media boss in response to a journalist request, although in a statement he claimed that "there was no intent to mislead".
Murrell, who has been in charge of the party's backroom operations for more than 20 years, had also come under fire for the way the SNP's executive was running the leadership contest to find a successor to his wife.
There were accusations of bias towards one of the candidates in particular, Humza Yousaf, who was widely understood to be Sturgeon's preferred candidate, and who eventually won the race to be the party's new leader, and Scotland's first minister.
Nicola Sturgeon announced in February she was stepping down after eight years in power, saying at the time she needed more privacy for her personal life, and saying she was running out of energy.