Just minutes before Oscar Arfmann allegedly shot and killed an Abbotsford, B.C., police officer, he told witnesses they would "see what he would do to the cops," if they were called, a courtroom heard Monday.

Arfmann, 66, is charged with first-degree murder in the Nov. 6, 2017 shooting death of Const. John Davidson. He pleaded not guilty as his trial kicked off in B.C. Supreme Court in nearby New Westminster.

In her opening remarks, Crown prosecutor Theresa Iandiorio laid out a timeline of the events that ended with Davidson lying facedown in an Abbotsford parking lot, shot twice from behind.

She said two car dealership employees confronted Arfmann that morning after they spotted a black Ford Mustang that had recently been stolen from their lot. The car was parked in a disabled spot outside the Mount Lehman Business Centre, Iandiorio said.

They told Arfmann that the police were on their way, and he "told them that they would see what he would do to the cops when they got there, or words to that effect," Iandiorio said.

Arfmann wore a black sweatsuit in court, his long grey hair reaching to his shoulders, his beard and mustache unshaven.

Davidson's family members wore black and occupied the first row of the packed courtroom. A uniformed member of the Abbotsford Police Department was front and centre. Davidson was 53 when he was killed. He had been a respected member of the force for 11 years, and was known for developing a strong connection with the city's young people.

The key issue in the trial will be identification, according to Iandiorio; whether the Crown can prove conclusively that it was Arfmann who fired the gun that killed Davidson.

Davidson was shot and killed in a parking lot in November 2017. (Abbotsford Police Department)

The court heard the Mustang was stolen from MSA Ford Sales in the Fraser Valley Auto Mall on Nov. 4, 2017. Two days later, staff at the dealership noticed the missing car parked outside a Quizno's restaurant, bearing Alberta licence plates.

An employee called police and boxed in the stolen car with his pickup truck.

When Arfmann returned, two employees confronted him, Iandiorio said. He pulled out a knife, and as the men backed away, he pulled a gun and fired twice at the pickup truck, the court heard.

Officers lined B.C.'s Hwy. 1 to pay their respects to Davidson, on Nov. 7, 2017. (Bill Cook)

Arfmann then got back into the Mustang, did a multi-point turn, hopped the curb and pulled out of the parking spot. Before driving away, he allegedly stopped and aimed his gun at the pickup truck once again, but it jammed when he tried to fire.

Multiple witnesses called 911 to report the shots and Davidson was the first on the scene, driving an unmarked white truck with his police lights on.

The two men met in the parking lot of the business centre, the court heard, where Arfmann allegedly "ambushed" the officer.

Davidson was shot from behind, landing face down on the ground.

Arfmann then "stood over Const. Davidson, who was face down and motionless, and shot Const. Davidson a second time," Iandiorio said.

Justice Carol Ross at the trial on Monday. (Jane Wolsak)

As the shooter drove away, several witnesses ran to help the fallen officer. An employee of a nearby insurance business was the first to reach Davidson.

"When she saw that Const. John Davidson was unresponsive, she grabbed his police radio and tried to call for help," Iandiorio said.

These Good Samaritans were soon joined by police, paramedics and doctors, who all tried their best to save Davidson's life, but he was pronounced dead at around 1 p.m.

Arfmann was located a short distance away from the scene not long after the shooting. Police rammed his vehicle and then shot him before they were able to take him into custody, the court heard.

Iandiorio told the court the Crown intends to call about 30 witnesses, who will help paint a picture of what happened on that day. The trial is expected to last eight weeks.