Calgary police Const. Chris Harris was so alarmed by the beating he witnessed during the "out of control" arrest of Clayton Prince, he tried to get his fellow officers to stop their attack by yelling "Youtube alert" in hopes they'd be scared a member of the public was recording a cellphone video.

Harris was the second witness for the prosecution in the trial of Calgary police officers James Othen, Kevin Humfrey, and Michael Sandalack, who are each charged with assault causing bodily harm.

Earlier in the day, Prince testified he was hospitalized for five days with broken ribs and a collapsed lung after the officers "beat the shit" out of him. 

A video was played for provincial court Judge Margaret Keelaghan in which Prince could be heard screaming in pain, though the incident is taking place off camera.

Harris testified the officers made "no meaningful attempts" to put the suspect in handcuffs, continuing the beating with their fists and knees instead.

"It was clear that Mr. Prince's reaction was one of pain," said Harris. "It appeared he wasn't resisting the officers, he was attempting to move away from the pain."

Clayton prince injuries

Photos show some of the injuries Clayton Prince sustained when he was arrested by Calgary police officers who are now on trial. (Clayton Prince)

Clayton Prince testified earlier that he was lying face down with his hands on his head as the officers delivered what the prosecution has called "tremendous violence."

"They beat the shit out of me and I was just laying there," said Prince.

The three officers sat shoulder to shoulder in the prisoners' box dressed in suits.

The resident of High Level, Alta., had been in Calgary for the Chasing Summer music festival with his girlfriend on July 30, 2016, when police pulled him over for a traffic stop in a parking lot in the 6700 block of Macleod Trail.

Instead of complying with the first officer's demands to stay in the car, Prince says he took off because he was paranoid after taking cocaine and marijuana and had been driving without a licence.

Clayton Prince

Clayton Prince is the alleged victim of three Calgary police officers who are accused of 'tremendous violence' during an arrest. Prince suffered broken ribs and collapsed lung as a result. (Meghan Grant/CBC)

After running through a sushi restaurant, Prince said he tried to hide in some trees but was flushed out by more officers who arrived on scene. When one officer pulled a gun, Prince got down on the ground and put his hands on his head. 

"I immediately got to the ground because I didn't want to get shot," said Prince. "I was expecting to get handcuffed and thrown in a car."

Even though Prince was complying with police demands at that point, Othen and Humfrey began to attack, said the Crown.

"[They] delivered tremendous violence to Mr. Prince while he was surrendered," said prosecutor Jim Stewart in his opening statement. "In response to that violence, he thrashed and moved."

5 days in hospital

Prince suffered a collapsed lung and broken ribs from that beating. Afterwards, he said he was thrown into a police car, which split his lip, and then punched behind the ear with a key.

"Then Constable Othen, in a cruel and unnecessary way, continued his assault on Mr. Prince," said Stewart.

Eventually, the officers called an ambulance for Prince, who said he couldn't breathe. He spent five days in hospital, but it was several months before Prince says he could move around without pain because of his broken ribs. 

The area where he was punched with the key became infected.

Othen also faces charges of mischief and assault with a weapon for allegedly digging the key into Prince's neck, while Humfrey is also charged with two counts of public mischief.

Officers accused of lying in reports

The mischief charges relate to false statements the two officers are alleged to have given after the incident.

"In an effort to change the narrative from the truth, both James Othen and Kevin Humfrey made false statements to [a constable], who they knew was in charge of writing up the report," said Stewart.

Both officers are also accused of submitting further written false statements.

Eventually a video from a police dashcam surfaced contradicting the officers' accounts of the incident, prompting an investigation led by the Alberta Serious Incident Response Team (ASIRT). 

Defence lawyers Alain Hepner, Paul Brunnen and David Butcher, who represent the officers focused their cross-examination on Prince's history of driving without a licence, his drug use and the path he took after he ran from the officers.

Othen and Humphrey are suspended without pay while Sandalack is on administrative duties.

The trial is set to last all week.