BARRIE, Ont. -- A Barrie police officer was captured on video delivering repeated blows to a man's head as he lay pinned facedown on the ground with his arms behind his back -- all because of a broken Christmas ornament.

The troubling video, which was played in court on Wednesday, shows Const. Jason Nevill speaking to the man and then suddenly beating him to the ground.

Nevill is on trial charged with assault causing bodily harm, fabricating the evidence against the victim and obstruction of justice.

The beating was caught on the mall security video which shows Nevill repeatedly punching and kneeing, Jason Stern, 25, of Barrie, who was pinned to the ground by two mall security officers.

Stern appears to have gone limp and unconscious twice, but still the officer can be seen punching him in the head.

"I didn't know why I was being beaten -- I kept pleading with him, 'Stop, stop, I'm a good person'," Stern said on the witness stand. "Then I blacked out."

He said he came to and the punching was still going on.

The entire incident began with the video showing Stern walking through the Bayfield Mall with his girlfriend and another couple after a midnight game of bowling when suddenly his friend, Simon, playfully reached up and took a swipe at a Christmas ornament, breaking.

The foursome then exit the mall but Stern returned because he forgot his wallet.

He was met at the door by two security officers who ask him to remain until police arrive. Stern is seen waiting patiently with the two security officers, not knowing he was facing any trouble.

As Nevill approaches, the two can be seen talking when Nevill attacks Stern and wrestles him to the ground.

"He asked me what my friend's name was," Stern explained.

"I didn't want to tell him. I figured the worst that could happen was I would have to pay for the Christmas ornament."

Court heard Nevill later told police that Stern had attacked him first by kneeing him in the groin and that he only punched Stern twice. However, the video shows Nevill delivering about a dozen blows to Stern's head without ever being attacked.

"I was terrified. I was so confused," Stern said, noting he had never been in a fight or previously run into trouble with police.

"I will never know to this day why it happened."
The trial continues.