The hole through the windshield on the marked RCMP truck driven by Haines Junction Cpl. Kim MacKellar was caused by a bullet, a firearms expert testified this morning.

Laura Knowles told the Yukon Supreme Court jury her investigation of the windshield indicates the bullet would have been fired from directly in front of the police vehicle.

The degree of cracking around the bullet hole indicates it came from a weapon capable of firing bullets at speeds greater than 2,000 feet per second.

Knowles testified the .375 H & H rifle she was sent for examination has a muzzle velocity of between 2,400 and 2,500 feet per second.

Three bullet casings she was sent for examination were fired from the .375 H & H, she testified.

Knowles said the hole through the dashboard radar control box was caused by the bullet fired through the windshield.

The location of the hole is consistent with the bullet's change of direction after it hit the windshield, she said.

Knowles testified the damage to the left breast pocket area on MacKellar's yellow RCMP jacket – stained in red – was consistent with bullet fragmentation from the bullet that was fired.

The damage to his duty shirt and bullet proof vest was also consistent with bullet fragmentation, she said.

Knowles said the bullet fragmentation collected from the RCMP vehicle was not sufficient for an analysis to determine if it came from the .375 H & H she examined.

She described fragmentation damage in several areas of the truck, including the dash, the driver's side head rest and the area of driver's side window.

Although Knowles testified she did not have any evidence of how the drivers side window was smashed out, there's a possibility it was caused by fragmentation of the bullet.

Christopher Cornell, 32, and Jessica Johnson were charged on Sept. 26, 2011 with attempting to murder MacKellar and deputy conservation officer Shane Oakley by firing a rifle at them during a high-speed chase along the Alaska Highway.

They were also charged with using violence and spraying custodian Frank Parent while robbing or attempting to rob Madley's General Store in Haines Junction.

Justice Leigh Gower of the Yukon Supreme Court declared Knowles is an expert in firearm analysis after she explained her work experience and educational background, which included a degree in mechanical engineering.

The nine women and five men of the jury began hearing evidence last week. The trial is scheduled to continue next week.