A “JEALOUS” ex-copper battered a police inspector after he caught him having sex with his wife outside a Screwfix, a court heard.
Gavin Harper, 45, is accused of stalking PC Stephanie Glynn following the breakdown of their marriage.
He bugged her vehicle, took her phone and hacked her social media, a jury was told.
Prosecutor Ryan Rothwell said Harper followed her to the car park at 11.45pm in February 2021.
Harper then flew into a rage when he caught her having sex with acting inspector Andrew McLullich, in his Kia Sportage, Liverpool crown court was told.
It is alleged Harper was holding up his phone while shouting: “I’ve got you on film s****ing my wife.”
Mr Rothwell, who described Harper as “jealous” after his two-year marriage broke down in 2020, said: “Miss Glynn began a sexual relationship but Mr Harper couldn’t let go. He obsessed over it.
“He did everything he could to make her life hell, affect her career, and to stop the pair seeing each other.
“One night, he tracked her to the Screwfix car park in Birkenhead. He found her and Mr McLullich having sex, trousers down, in the back of Mr McLullich’s car.”
Harper punched him in the face then appeared to grab something from under his wife’s car, which Miss Glynn, 40, believed to be a tracking device.
Mr McLullich scuffled with Harper over the item, and was allegedly struck at least twice with a torch, leaving him with blood pouring from two deep cuts and needing six stitches.
Mr McLullich had struggled to get out of the car as his trousers were still around his ankles, the jury heard.
Miss Glynn said she and her new boyfriend had been kissing in the front when “one thing led to another”.
Speaking from behind a screen, she added: “To put it bluntly we began having sex. We were clothed from the waist up but both naked from the waist down.”
The prosecutor explained Harper and his wife had been fighting for custody of their dog Maisie.
During the attack, she said he had a “deranged” look in his eyes and told her he would “kill the dog rather than let her have it”.
Harper, of the Wirral, told the force the pair had been having sex on duty.
The claim was investigated but no further action was taken.
Harper is also accused of driving by his rival’s and ex-wife’s mum’s homes.
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He denies stalking and unlawful wounding.
Trial continues.