Const. Kwesi Millington's perjury conviction comes more than seven years after Dziekanski's fatal confrontation with police, which stained the image of the RCMP and led to sweeping changes to how officers across the country use Tasers.
Millington was among four Mounties summoned to Vancouver's airport in October 2007 after Dziekanski, who spoke no English, started throwing furniture in the international terminal. Millington fired his Taser less than a minute after arriving.
The officers, who were never charged for their actions on the night of Dziekanski's death, were compelled to explain what happened at a subsequent public inquiry, and all four were later charged with perjury.
The Crown alleged they lied when they attempted to reconcile their initial accounts of what happened with an amateur video released later. Prosecutors accused the officers of colluding on a story to tell investigators and then lying at the inquiry to cover it up.
B.C. Supreme Court Judge William Ehrcke described Millington's explanations at the inquiry to be "simply preposterous" and he concluded the officer had a strong motive to lie.
"The discrepancies are all in one direction: that of exaggerating the threat posed by Mr. Dziekanski," Ehrcke said Friday, as Millington listened from the prisoner's dock.
"I find his explanation to be patently false."
For example, Millington initially said Dziekanski remained standing after the first jolt of the Taser and that the four officers wrestled the man to the ground. The video clearly shows Dziekanski fell to the floor on his own almost as soon as he was stunned.
Millington told the inquiry he thought Dziekanski was standing when he pulled the trigger a second time and he said he honestly believed the officers wrestled Dziekanski to the ground, though he acknowledged in the face of the video that he was mistaken.
Ehrcke concluded the officers must have spoken to each other before providing statements to homicide investigators, but all four Mounties denied that.
"This the only rationale inference available," Ehrcke said.
Another officer, Const. Bill Bentley, was acquitted in 2013, while two other cases have not yet concluded.
The verdict places the Crown in the awkward position of having a conviction against one officer and an acquittal for another, despite the fact that prosecutors' theory was that the four officers all lied together. A Crown spokesman declined to comment about the apparent contradiction other than to say the cases were different.
Dziekanski's mother, Zofia Cisowski, who sat quietly in the public gallery as the judge read the verdict, said Friday was the first time she has been happy since her son died.
"I am the happiest person all over the world," said Cisowski, who lives in Kamloops, B.C., where Dziekanski planned to move after immigrating to Canada.
"I have no words."
Millington testified in his own defence.
He told the court he had no reason to lie because he has always believed he did nothing wrong. He denied colluding with the other officers.
The Crown also alleged the officers met in the Vancouver area in early 2009 to plan their testimony. A witness, whose ex-husband is Bentley's cousin, told the court the officers met at her home, but her ex-spouse said the meeting happened months later.
The judge said there was evidence the officers met at the woman's house at some point in 2009, but it wasn't clear whether that happened before or after their testimony at the inquiry.
Lawyers will meet again in March to set a date for a sentencing hearing.
Former corporal Benjamin (Monty) Robinson is awaiting a verdict and Const. Gerry Rundel's trial, which proceeded in another courtroom on Friday, is almost finished.
The Crown has filed an appeal of Bentley's acquittal.
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