Hamilton Sheriff Court heard how he also headbutted his 42-year-old girlfriend and strangled her, in attacks which left her bruised and in pain.
On one occasion the thug officer told his faithful victim she “deserved” the abuse – which saw him attacking her while “frothing at the mouth” with his “eyeballs popping out his head.”
The bully would beat her down to the ground, pin her down with his bodyweight – the way he did when arresting violent criminals whilst on duty – and then clamp his hand over her nose and mouth, leaving her unable to breathe.
The attacks left Miss Hirdman, who has a heart condition, hyperventilating – and one even left her feeling like she was having a heart attack.
He would call her “pathetic, paranoid, insecure and a b**ch” and would attack her “in a rage” – even threatening to push her “down the f****** stairs.”
He beat her so badly she became a recluse and, with the help of friends and family, tried to rent a flat and move out without his knowledge.
The callous creep insisted in evidence he hadn’t repeatedly physically and mentally abused her, branding her a “jealous, paranoid and vindictive liar.”
Despite admitting he regularly physically and verbally fought with her, he denied assaulting her, claiming he had to restrain her several times because she attacked him when he tried to dump her.
But Miss Hirdman had made secret recordings – and the files were a key piece of evidence used to nail Ross for the abuse.
In one recording, he chillingly boasted he was “a f****** monster” and told his faithful victim – who refused to go to police for years because she didn’t want him to lose his job – she “deserved” to be beaten up.
He said: “You deserve what you get as you know what is going to f****** happen and you refuse to stop.
“You still keep pushing, and pushing, and pushing, and then you’re surprised when I’ve f****** snapped.
“I’ve done things I never thought I would ever f****** do.”
He was also recorded saying “it would be different” if he had hit Miss Hirdman “out of nowhere” and “for no reason.”
Ross admitted he had called her names and said: “I have said some terrible things in the heat of the moment.
“It’s something that I obviously regret – it’s not what I would normally do.”
As she asked Sheriff Ross Macfarlane QC to convict Ross, Prosecutor Jennifer Guy said: “He is not the calm, well dressed man we have seen in court for six days – he’s the violent, angry, aggressive man the court heard on the recordings and described by Miss Hirdman.”
And his prison fears may become a reality after he was convicted of three assaults on Miss Hirdman – one in October 2017, one in September 2018, and one in August 2019, at his home in Motherwell, Lanarkshire.
He was also found guilty of behaving in a threatening or abusive way towards her, between December 2013, and March 2019, by repeatedly shouting, swearing, behaving aggressively towards her, threatening her and making “derogatory remarks.”
As he convicted him, Sheriff Macfarlane said: “We saw graphic photographs of injuries and heard distressing audio recordings – including threats made by you.
“In all the circumstances I find the Crown has proved the case beyond reasonable doubt and I find you guilty.”
He then adjourned sentencing, for background reports to be prepared, until next month – when Ross could be caged for as long as 12 months.
Police Scotland has been approached for comment.
Don’t miss the latest news from around Scotland and beyond – Sign up to our daily newsletter here.