During the trial, the court heard how Ross raped the first woman after they met at a party on Lewis between August and October 2012.
The woman told the court how Ross “pinned her down to a bed” before carrying out the attack.
She said the incident had left her traumatised.
A second woman told the trial Ross had sat on her and restrained her before raping her in June 2014.
He went on to subject a third woman to a course of abusive behaviour between October 2019 and June 2022 in Inverness.
In evidence, the court was told Ross threatened to kill the woman, repeatedly pushed and pulled her, threw her to the ground and brandished a knife at her.
Ross was also convicted of behaving in a threatening and abusive manner on 5 June 2022 at an address in Inverness, where he shouted, swore and acted aggressively.
He later attempted to pervert the course of justice on that date by trying to speak to a woman who was providing a witness statement to an officer.
Ross has been placed on the sex offenders register indefinitely.
Faye Cook, of the Crown Office and Procurator Fiscal Service (COPFS), said Ross had carried out “deliberate and repeated acts of abuse against women over the course of a decade”.
She added: “This was sustained offending, which caused significant harm.
“As a police officer, he was in a position of trust. Instead of upholding the law, he chose to break it in a serious and persistent way.
“I would urge anyone affected by similar offending to come forward and report it.
“The Crown is committed to prosecuting those responsible for sexual and domestic abuse, regardless of who they are.”