The force said he had been a special constable at the time of the offences involving the teenage girl in 2014 and 2015, and a serving officer during the attacks in 2020 and 2022.
Detective Superintendent Stevie Bertram, of Police Scotland’s public protection unit, said: “Reports of violence against women and girls are rising and it is of the utmost importance for Police Scotland to play its part in tackling this national emergency.
“Our thoughts are very much with the victims in this case, and I wholeheartedly commend their strength in reporting these crimes. This was the crucial first step in bringing Williamson to justice.
“Williamson will now face the consequences of his actions and today’s outcome should highlight our determination to relentlessly pursue the perpetrators in these investigations.
