Steven Purcell, the former leader of Glasgow council, has been questioned by police after he claimed he he took cocaine.
He went voluntarily to a police station on Wednesday as part of an ongoing criminal investigation, Strathclyde police said.
Mr Purcell was seen as Scotland’s most powerful out gay man until March, when he resigned citing exhaustion.
In the following weeks, a string of lurid allegations emerged about him, including that he had taken drugs and was involved in corruption.
After treatment in a private hospital specialising in addiction, he gave an interview to the Scottish Sun in which he said he had taken cocaine a “handful” of times and admitted to alcohol problems.
A police spokesman said: “Strathclyde police can confirm that Steven Purcell attended voluntarily at a police office in Glasgow on Wednesday June 2nd to assist with an ongoing criminal inquiry.”
Glasgow’s LGBT centre is at the heart of claims he was involved in corruption and one of his closest allies, the centre’s boss Ruth Black, has been questioned twice by police over allegations she procured drugs for him.
Ms Black was also reportedly questioned over claims Mr Purcell used undue influence to award her a £50,000 a year contract to run the new lesbian and gay drop-in centre.
The 37-year-old was ranked at number 16 last year on PinkNews.co.uk’s 50 most powerful gay, lesbian and bisexual people in British politics. Last year, he was named Scottish councilor of the year.
Before his resignation, he was tipped as a future leader of Scottish Labour. He was elected, unopposed, as leader of Glasgow city council in May 2005 at the age of 32 and came out a year later.