Phil Gormley, the chief constable of Police Scotland, has quit amid investigations into several allegations of gross misconduct.
The Scottish Police Authority confirmed he had tendered his resignation with immediate effect.
In a statement on its website the SPA said: “Chief Constable Gormley requested a leave of absence in September 2017 to facilitate ongoing investigations into allegations made about him, which he denies.
“It has become clear to Chief Constable Gormley that irrespective of the outcome of the ongoing investigations he will not be able to resume his operational role in Police Scotland in a meaningful way, and the ongoing disciplinary process may take some time to complete.
“He has therefore decided to step down and end his contract 10 months early in the interests of the office of the Chief Constable and to allow Police Scotland to move forward with their agenda and strategy which he previously set in motion.”
It comes amid a series of misconduct allegations and investigations made against the chief, who was appointed in 2015.
He has been on special leave for several months.
Mr Gormley said: “The last eight months have been difficult for me and my family, in particular I would like to thank my wife for her love and loyalty. The events since November 2017 have led me to the conclusion that it
is impossible for me to resume my duties in a meaningful way prior to the end of my contract.
“I now need to prioritise the health and wellbeing of my family on whom these events have taken a significant toll.
“The support of colleagues from across the UK with whom I have served during the last 32 years has been a source of great strength.
“As Chief Constable of Police Scotland I have had the privilege to meet and work with some exceptional people, I wish them well for the future and it is in their interests that I feel it is right to step aside.”
Susan Deacon, chairman of the SPA, thanked Mr Gormley for his contribution and said it had been a “challenging period for all concerned”.
She added: “We now need to move on.”
The former chief will be paid for his three months notice, but will not have to work during it, and will be paid for outstanding leave. He will receive no further settlement.