ST. JOHN'S, N.L. -- Nelson Hart told police a clash with prison guards started over a spilled lunch and escalated into a beating that left him bruised, an officer with the Royal Newfoundland Constabulary testified Thursday.

Hart, who was imprisoned in St. John's, N.L., pending an appeal of a murder conviction in the deaths of his twin daughters, was in court on three charges of making threats and one count of mischief to property.

Const. Matthew Dixon told provincial court the dispute began June 24, 2013, when, according to Hart, a prison guard shoved his lunch plate through his cell door slot and onto the floor.

A silent prison security camera video entered as evidence and played in court shows Hart laying on his bed as an item falls near the door.

Dixon said Hart told police he came out of his cell and when a guard told him his lunch was on the floor, he grabbed a kettle from the common kitchen area and threw it into a wall-mounted TV.

The video shows Hart whipping the kettle at the television. He then heads back into his cell when a male correctional officer shoves him into a wall and then onto the floor of his cell with two other guards behind.

Hart is seen on the video laying face down as those guards leave. Hart appears to be pointing and yelling toward his closed cell door before he lays down on the bed.

Minutes later, footage from outside the cell shows 10 guards responding. Eight enter Hart's cell and swarm him as they pull him to the floor and take him to a segregation unit with his pants around his ankles.

Hart told police that at one point he was punched as one of the guards told him to "squeal like a pig," Dixon said.

Dixon testified that when he took Hart's statement two days after the incident, he saw purple bruising on his left shoulder, both upper arms and scratches behind his left ear.

Hart's defence lawyer Jeff Brace later asked Jeff Mackey, the investigating Royal Newfoundland Constabulary officer, why he laid charges against Hart and not the guards.

"I didn't see any punching going on there at all," Mackey replied as Brace reviewed the video with him.

Correctional officer Krista Williams also testified that, as far as she knew, none of the guards hit Hart.

She said she didn't know how Hart's lunch hit the floor. She said Hart was told another meal was on its way but he became volatile, telling the guards they were all "going to get it."

Williams said it's not unusual for at least six correctional officers to help remove inmates during a "cell extraction."

The trial continues April 1.

Hart, 46, has been free since the Crown decided last August it lacked enough evidence to retry him for murder in the 2002 drownings of his three-year-old daughters at Gander Lake.

A Supreme Court of Canada ruling last July concluded that confessions Hart made to police posing as gangsters during a so-called Mr. Big sting were inadmissible. It said those tactics potentially infringed Hart's Charter rights and cast doubt on the reliability of evidence drawn from similar investigations across Canada.

The judgment affirmed a 2012 appeal court decision overturning Hart's 2007 first-degree murder conviction and life sentence.

Hart was convicted Wednesday of threatening a guard in a separate prison incident in January 2013.