What happens next following Nicola Sturgeon arrest?

When the first reports of a police investigation into the finances of the Scottish National Party emerged few people - this writer included - thought it would amount to much.

The mere fact Nicola Sturgeon was arrested as a suspect as part of those investigations, questioned for seven hours and released without charge, shows it amounts to a great deal.

Now, the former First Minister has said that she "knows beyond doubt" that she is innocent - though of what we do not know - but even as things stand this is another very difficult day for the SNP, and for her successor, Humza Yousaf.

Mr Yousaf has today said that he sees "no reason" to suspend Ms Sturgeon from the SNP 'whip' at Holyrood, in effect throwing her out of the party's group in the Scottish parliament.

Critics within the party, including SNP former MP turned MSP Michelle Thomson say that should happen.

Ms Thomson had the Westminster whip taken away after allegations about a business she was involved in. She points out she was never personally investigated or arrested. 

Others including former leadership contender, SNP MSP Ash Regan, and MP Angus Brendan MacNeil have made similar calls. 

Since he took over from Ms Sturgeon - a close ally - as party leader and First Minister Mr Yousaf has not had his troubles to seek. 

Much of his time has been taken up on internal SNP matters. Finding an auditor or dealing with earlier arrests.

The questioning and release without charge of Peter Murrell, the SNP's former chief executive (Ms Sturgeon's husband) and ex-Treasurer, MSP Colin Beattie.

On top of that, there have been a series of policy problems - over budget and much delayed new ferries for CalMac, putting off the planned deposit return scheme after a Westminster intervention to limit it, putting plans for a National Care Service on hold.

Plenty of other issues could be added to the list, including divisions inside his party over gender reform laws, but together all of these amount to a nightmare start to his premiership. 

There has quite simply been no honeymoon period for this new First Minister. And little time to set out his own vision of where he wants to take Scotland, beyond the obvious desire of a nationalist to break from the UK.

What happens next?

The question now for Mr Yousaf and the SNP is what happens next? There are legal restrictions on what can be reported already. But we can say this.

All three of the SNP then senior officer bearers - Ms Sturgeon, Mr Murrell and Mr Beattie - have been arrested as suspects, questioned and released without charge.

The Police Scotland investigations continue. For how long and what precisely the detectives are doing, we do not know, and even if we did we could probably not say for sound legal reasons.

Under Scots law, the Criminal Justice Scotland Act (2016), police can re-arrest any suspects. 

The police can ask the prosecution service, the Crown Office and Procurator Fiscal Service (COPFS) for advice. They have already consulted them.

In the end, they will send a report to the Crown Office who will consider whether there is enough evidence a crime has been committed, and decide whether to prosecute.

Part of the test of that is the public interest and whether the individuals concerned were in positions of trust.

Or the Crown can decide after all the investigations that there is not enough evidence to go to trial.

The timing of all of that is a matter, quite properly, for the police and the Crown Office. So it's a waiting game.

The public will have to wait. Nicola Sturgeon will have to wait. And so too will Humza Yousaf.