Police Scotland consulted the National Crime Agency over its probe into the SNP’s finances.
The force sought assistance from the UK’s law enforcement body for an independent review of its inquiry last year.
The investigation, known as Operation Branchform, has led to the arrest of former party chief executive, and husband of former First Minister Nicola Sturgeon, Peter Murrell, and its then-treasurer, Colin Beattie.
Both were released without charge, while a motorhome was seized and the party’s offices and the home of Murrell and Sturgeon searched.
The NCA specialises in the investigation of serious and organised crime across the UK.
Operation Branchform began in July 2021 following a complaint about the way more than £600,000 of donations for a future independence referendum was spent.
Former FM Sturgeon, who has said she would fully cooperate with the investigation, previously described the experience as “traumatic,” but said the probe was not the reason she stood aside from the top job in Holyrood.
A Police Scotland spokesperson said: “As the investigation is ongoing we are unable to comment further”.
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