01/21/2015 11:41 EST | Updated 03/23/2015 05:59 EDT

Police witnesses weigh in at perjury trial of RCMP

An expert in the use of Tasers had to be shown frame-by-frame video before he would agree Robert Dziekanski was already on the ground when he was stunned a second time by an RCMP officer in 2007.

Initially Delta Police Const. Craig Baltzer said it appeared to him that Dziekanski was just "going to the ground."

It's a key difference that could figure significantly in the ongoing perjury trial of RCMP Const. Gerry Rundel.

Three of the six allegations against Rundel deal with his statement to homicide investigators in which he described Dziekanski swinging a stapler above his head before a fellow officer fired a Taser at him.

At the 2009 Braidwood Inquiry, Rundel testified he mistakenly combined what he saw during the first and second stuns which were six seconds apart.

All four officers involved made similar errors and the Crown alleges they were the product collusion to mislead investigators and the inquiry.

Taser expert testifies

The Crown called on Baltzer on Wednesday to bolster its case.

Baltzer is a veteran police trainer who has witnessed hundreds of uses of the Taser and has been stunned himself more than thirty times.

It was Baltzer who originally downloaded the firing data from the Taser used on Dziekanski for investigators.

However, Baltzer's opinion of what he saw in amateur video of the incident was less than straightforward.

"At the beginning of the second deployment was Mr. Dziekanski already on the ground?" Special Prosecutor Tony Paisana asked.

Baltzer paused for several seconds.

"It's right at that moment where he's going to the ground or just about at the ground where the second Taser deployment came into play."

It wasn't what the Crown was expecting to hear.

Paisana asked Baltzer to look at the video again.

"You agree with me at the time of the second deployment Mr. Dziekanski is on the ground?", Paisana asked.

"Yes. Going to the ground," Baltzer repeated.

After pointing to a specific frame marking the start of the second deployment, Paisana tried a third time.

"You agree he's on the ground at this point in the video?"

Baltzer finally agreed.

Kwesi Millington's trial

While Baltzer's evidence was admitted unopposed by Rundel's defence lawyer, the special prosecutor handling the perjury charges is opposing the use of experts in another court room.

For several days the lawyer Const. Kwesi Millington has tried to make the case to hear evidence from two Police authorities.

Millington fired the Taser the night Dziekanski died.

His lawyer wants to question police use of force trainer Sgt. Brad Fawcett of the Vancouver Police Department.

At the Braidwood Inquiry in 2009, Fawcett testified the actions of all four Mounties were "a reasonable escalation and de-escalation of force based upon the actions of the subject."

At the time Braidwood called Fawcett's opinion "blinkered."

The Crown is opposing him on the grounds that Millington isn't on trial for misusing the Taser and any use of force witnesses would be irrelevant.