If anyone knows anything about embezzlement, particularly at this scale.
It's NEVER a lone figure acting on their own accord.
There are always other people involved, there's just no paper trail.
For an organisation like the SNP which will have effective directors and treasurers and auditors, several people will have been involved. The others just weren't as careless as buying campervans directly with the money as their partner was the first minister of the country.