Ms Sturgeon addressed the issue at First Minister’s Questions when she came under attack from opposition leaders about how much the SNP knew about allegations of financial irregularities over property deals linked to Ms Thomson.
The First Minister has insisted she knew nothing of the allegations until they were reported in the media. But she added: “I am in no doubt whatsoever in my mind that if the allegations - and again I stress the word allegations - are proven to be correct, they will represent behaviour that I find completely unacceptable.”
Police have begun an investigation into transactions handled by Mrs Thomson’s former lawyer, Christopher Hales. He was struck off after a disciplinary hearing last year for his involvement in property deals linked to the Edinburgh West MP.
However fresh confusion emerged last night over when the Law Society of Scotland alerted the Crown Office to Mr Hales’ case, or informed them of the identity of his clients, who included Mrs Thomson. At a press conference yesterday the Law Society chief executive Lorna Jack sought to defend the year-long delay in contacting the Crown Office about Mr Hales, saying the issue was raised with prosecutors in April, a month before the general election.
But last night the Crown Office insisted they had been kept in the dark about the deals linked to Mrs Thomson until two months after the election.
A spokesman for the Crown said: “The Crown was not told of the identity of Mr Hales’s clients before we received the official report into Mr Hales’ conduct in July and we ordered a police investigation into the matter six days later.”
The Scottish Solicitors Disciplinary Tribunal report into Mr Hales which resulted in him being struck off was published in May 2014, but the Crown Office says it was not formally notified until July this year.
Ms Jack said this was not a deliberate move. “There was no purposeful delay,” she said yesterday. “We were pursuing the processes that we would normally pursue.”
Asked if the delays were down to the general election and involvement of a possible MP, Ms Jack insisted it was not.
“I can categorically assure you that it was not,” she said. The legal chief also defended the role of Sheila Kirkwood, who was secretary of the committee which handled the case against Mr Hales and is a member of the pro-independence Lawyers for Yes Campaign.
“She had no involvement in taking papers on the Christopher Hales case to the Law Society Guarantee Fund sub-committee and in no way delayed these papers being taken to the committee,” Ms Jack added.
She also stressed that Ms Kirkwood is “entitled to her personal political views”.
Mrs Thomson, who stepped down as business spokeswoman for the SNP at Westminster, insisted she “always acted within the law” and is focusing on clearing her name. She also offered to speak to police in connection with their investigation into Mr Hales.
Her solicitor Aamer Anwar said: “Over the last few days individuals have demanded full transparency from the SNP and the First Minister as to what they knew of the detailed nature of Michelle Thomson’s business dealings several years before she became an MP - the simple answer is none at all.
“Michelle Thomson maintains that she has always acted within the law.”