What is the past precedent for SNP suspensions?

First Minister Humza Yousaf has rejected calls to suspend Nicola Sturgeon from the SNP after his predecessor was arrested as part of a police probe of party finances.

Ms Sturgeon was released without charge and insists she is innocent, but has faced calls from opposition parties and some SNP politicians to step back from her party membership while the investigation continues.

This inquiry has taken the SNP into uncharted territory after years of stability at the top of Scottish politics, but there have been questions over the membership of some parliamentarians in the past.

What precedent will Mr Yousaf and Ms Sturgeon have to lean upon as they weigh up her future in the SNP?

The most immediate examples come from the same police investigation into party fundraising and finances, which has seen two other senior SNP figures arrested and released without charge.

The first was Peter Murrell, the party's former chief executive and Ms Sturgeon's husband - the arrest which sparked a two-day search of the couple's home in Glasgow. Mr Yousaf rejected calls for him to be suspended because he is "innocent until proven guilty".

Meanwhile Colin Beattie opted to step down as SNP Treasurer, but has stayed on as an SNP MSP - with Mr Yousaf saying "it is really important that due process takes place".

The first minister has leaned on these two examples as his reasoning for not suspending Ms Sturgeon, saying he has been consistent in his decisions.

But under Ms Sturgeon's leadership, there was a broad range of examples where MPs and MSPs resigned or were suspended from the SNP - which obviously cover quite different circumstances to her own.

Her predecessor Alex Salmond resigned his membership when he was accused of harassment, stepping back from the party while he took the government he once led to court over its investigation.

He said he intended to rejoin the SNP once he had cleared his name, but instead set up his own Alba Party after being cleared of sexual assault charges in a criminal trial.

Others have also opted to resign or voluntarily "step back" from the party whip or membership.

Natalie McGarry withdrew from the SNP whip at Westminster in 2015 - just months after being elected - amid a fraud investigation.

At the time, Ms Sturgeon said that was "the right thing to have done", although she added that Ms McGarry was "entitled to the presumption of innocence".

She left Westminster at the 2017 election, and was ultimately jailed for embezzlement.

Resignations are not always entirely voluntary though.

Michelle Thomson resigned the whip at Westminster in 2015 amid allegations of financial impropriety which ultimately led to nothing, with prosecutors announcing two years later that there was an "absence of sufficient credible and reliable evidence" against her.

She said she wanted to stay in the party, but was told it was "a case of go or be pushed" by senior figures in the party.

In a telling sequence of events, she published a statement saying she would co-operate fully with police - one minute before the party released the same statement, but with an additional line saying she had "decided to withdraw from the party whip".

The fact she was left sitting as an independent MP meant she was unable to stand for the SNP in the snap election in 2017, and lost her seat - although she has since been readmitted to the party and is now an MSP at Holyrood.

Ms Thomson has called for Ms Sturgeon to resign the party whip while she is under investigation, saying "her values should be consistent".

Others have been directly suspended by the party, without being given the option of jumping before they are pushed.

The MP Margaret Ferrier was suspended after admitting she had breached Covid lockdown restrictions, and Ms Sturgeon urged her to quit parliament entirely.

She sits as an independent MP but has now been suspended from the House of Commons too, meaning she faces the prospect of losing her Rutherglen and Hamilton West seat via a recall petition.

At Holyrood, the MSP Mark McDonald was suspended from the party amid harassment allegations which saw him quit as a government minister.

After serving a month-long suspension from parliament he saw out the term as an independent MSP, having quit the party ahead of a group meeting where his SNP membership was to be debated.

One of the stranger cases was that of Neale Hanvey, who was suspended from the party midway through the 2019 general election campaign after making a "clearly unacceptable" post on social media.

Although technically an independent candidate, the ballot papers in Kirkcaldy and Cowdenbeath had already been printed with the SNP logo next to his name - and he went on to take the seat from Labour's shadow Scottish secretary.

Mr Hanvey was readmitted to the party in May 2020, but less than a year later he resigned to join the newly-formed Alba Party.

To complete the broadest possible range of potential outcomes, the SNP MP Chris Law has pointed out that he was detained by police in 2016 as part of a financial investigation.

The Dundee West MP was questioned by officers about his Spirit of Independence campaign, but was released without charge.

He was not suspended from the party and was backed by the party leadership, and now says remaining in post "should be the right course for anyone that is in that position".