Mr Murrell has taken responsibility after misleading information was briefed to the media over the party’s membership numbers, but insisted there was no “intent to mislead” – remarks echoed by Ms Sturgeon.
But when asked if she knew about the decline in membership numbers, Ms Sturgeon told ITV News: “I didn’t. I wouldn’t have been able to put a figure on the [membership].”
She said the figures are assessed every year for inclusion in their accounts.
Ms Sturgeon added: “It’s not something that every day someone is checking what the membership number is. It fluctuates.
“I don’t track party membership every day, week or month… we have declined in membership from a very high point and that’s for a variety of reasons.”
The outgoing Scottish Prime Minister said some of the reasons for the fall in numbers are political, while some may have simply forgotten to renew their membership.
But despite the recent decline, Ms Sturgeon believes the SNP “has probably got more members than all of the other opposition parties combined. We don’t know that for sure because none of them publish their membership figures.”
The comments from Ms Sturgeon come after her husband resigned as the SNP’s chief executive with immediate effect.
READ MORE: Nicola Sturgeon squirms as she’s challenged on resignation
Reports had suggested members of the SNP’s ruling National Executive Committee (NEC) were threatening a vote of no confidence in Mr Murrell.
It followed the sudden departure of SNP media chief Murray Foote 24 hours earlier as the row over the party’s membership numbers erupted.
Mr Murrell said in a statement: “Responsibility for the SNP’s responses to media queries about our membership numbers lies with me as chief executive.
“While there was no intent to mislead, I accept that this has been the outcome. I have therefore decided to confirm my intention to step down as chief executive with immediate effect.
“I had not planned to confirm this decision until after the leadership election.
“However, as my future has become a distraction from the campaign I have concluded that I should stand down now, so the party can focus fully on issues about Scotland’s future.
He added: “The election contest is being run by the national secretary and I have had no role in it at any point.
“I am very proud of what has been achieved in my time as chief executive and of the part I have played in securing the electoral success the party has enjoyed over almost two decades.
“Fourteen national election wins is testament to the skills of the dedicated and talented HQ team that I have been privileged to lead.
“They gave their all to the party and the independence cause and I thank them for it.
“I have worked for independence all my life and will continue to do so, albeit in a different capacity, until it is achieved – and I do firmly believe that independence is now closer than ever.”
Meanwhile, two of the contenders to succeed Ms Sturgeon have said the SNP must understand why the 30,000 members left the party in just over a year.
Health Secretary Humza Yousaf told LBC Radio it would be for a new leader to find out why so many have left the party.
He said: “First of all, the new leader, one of the first things they have to do internally is get in amongst the weeds and understand why we lost those members,” he said.
“Is it because, for example, people don’t see we’ve made enough progress on independence and have been talking too much about process and not enough about policy?”
Former community safety minister Ash Regan also said: “When large numbers like that leave, I think the sensible thing to do is to look into that and say, ‘why are we losing members and what can we or should we be doing about it?’ ‘
“I’m the only candidate here that set out an SNP action plan when I first announced my candidacy several weeks ago, the idea behind that being that we need to make members feel valued, we need to reflect the interests that they have, we need to modernize the party and bring back the democracy that I think is missing.”
