An Arkansas police officer is facing manslaughter charges for allegedly shooting a fellow cop who was knocking on his door.

36-year-old Scott Hutton was shot dead through the front door of his colleague Calvin Salyers’ home, while he was calling in to pick up a patrol car.

According to investigators, the 33-year-old Alexander PD officer had previously told another colleague that he would “shoot through the door” any protesters that came to his home, in the wake of unrest following the death of George Floyd in May.

According to court documents seen by Buzzfeed, Hutton drove to Salyers home around 7pm on June 3, in order to collect the car, which was parked in a nearby structure.

Salyers, who was off duty, was inside watching a movie with his girlfriend at the time.

When Hutton arrived, he texted Salyers “are you awake”; when he didn’t get a reply, he knocked at the front door.

According to the arrest affidavit, Salyers told his girlfriend he was going to check who was at the door, grabbing his Glock .40-caliber handgun as he did so.

Looking through the peephole, he said he saw a “figure standing on his porch with a dark shirt and a gun on his hip”.

But while transferring the gun from his right hand to his left, he said the gun accidentally went off.

The bullet went through the wooden front door and glass storm door, and into Hutton.

He said he then realized who the man was, called 911 and attempted to perform CPR.

Hutton was rushed to hospital, but doctors were unable to save him. He was wearing a black polo shirt, khakis, a “typical” police officer belt, and his badge when he died, the affidavit stated.

Investigators found evidence the gun had been pressed against the door when it was fired, and that Hutton was “standing at an angle and not squarely facing the door” when he was shot.

As part of the investigation another officer, Sgt. Matt Wharton, reported that Salyers had previously warned that if any police brutality protesters came to his door he would shoot them through it.

The sergeant admonished him for the threat, calling such an action “reckless and negligent,” insisting police should not shoot anyone without identifying them first and establishing they were a threat.

Salyers, who has been with Alexander Police Department since 2017, surrendered himself on Wednesday; his bond is set at $15,000.

A GoFundMe to raise money for Hutton’s wife of five years says he “died in the line of duty”; it revealed he had “achieved his dream of becoming a police officer”, having been medically retired following two tours with the United States Army National Guard.