Scotland’s chief constable, Sir Iain Livingstone, has said the decision to raid Nicola Sturgeon’s home in April and erect a large tent across the entrance was “proportionate and necessary.” In an interview with the Sunday Times to mark his retirement, Livingstone denied that the move was politically motivated and said the search warrant was independently approved by a judge. He said Operation Branchform, an inquiry into the Scottish National party’s finances and its use of more than £600,000 of donations from independence supporters, had been long-running and exhaustive. “When we carry out the search we will put processes in place that are proportionate and necessary to the action being carried out, and to the inquiry and its terms, and I am satisfied that the steps we have taken are proportionate and necessary,” he said. “Stating opinion or speculation without having the knowledge and information that exists is damaging … because it infringes the rights of individuals. Operation Branchform has integrity, it is expected to have rigour. If the operation had not been pursued, I would rightly have been accused of neglect of duty.” Sturgeon’s husband, Peter Murrell, was arrested in the couple’s home shortly before the search took place. After nearly 12 hours of questioning by detectives, he was released without charge pending further inquiries. Nearly two weeks later, the SNP’s then treasurer, Colin Beattie, was arrested at his home and questioned by police. He too was released without charge, pending inquiries. The decision to erect the large tent outside Sturgeon’s home provoked a furious response from her allies, who accused the police of unjustified theatrics. Murray Foote, the SNP’s former head of communications at Holyrood, told the Daily Record in early May that the use of tents was a “grotesque circus”. He claimed that if no charges or prosecutions ensued “then the reputational cost [for the police and Crown Office] will be far more substantial than the cash spent on manpower.” There has been widespread speculation that Sturgeon too could face arrest: she has repeatedly denied any wrongdoing but was party to tense internal debates about the SNP’s finances after questions emerged about its accounts. She is yet to be interviewed by police. The former first minister has begun a weekly newspaper column in the Glasgow Times and has resumed public speaking engagements. Livingstone confirmed he was aware in advance that the forensic tent would be used. “I was aware of it and was supportive of it because I knew the circumstances and the rationale for utilising it, and part of it was to protect rights of individuals,” he said. Asked if any further arrests would follow, he said: “I would never comment on operational matters.”