The officer was heard to make the comments in a video uploaded to YouTube by a man who had had his camera seized following an accident
A policemen threatened to make a man’s day a “living hell” after he photographed the scene of a car crash.
The 26-year-old recorded the officer on his phone and posted it online.
The sergeant said: “You’re lucky I didn’t knock you out. I swore at you, yeah. It got your attention, didn’t it?”
The officer added: “We’ll nick you now and I will make your day a living hell because you’ll be in that cell all day.”
He seized the camera but gave it back.
Gloucestershire Police said a misconduct probe is ongoing.
The accident on November 19 involved a woman of 86 hit by a vehicle in Churchdown, Glos.
She died later in hospital.
Gloucestershire Police Commissioner Martin Surl said: “Police should deal with the public in a civil manner at all times.”