But in passing judgment, Superior Court Justice Gary Hearn added his voice to a growing chorus of those who believe the so-called robocalls affair was not the work of a single rogue operator acting alone.
Sona, 25, the only one ever to be charged in the case, hung his head in the Guelph, Ont., courtroom while nearby family members fought back tears as Hearn delivered his verdict.
The judge rejected the inconsistent and "largely self-serving" testimony of the Crown's star witness, Andrew Prescott, who held out for an immunity deal before agreeing to testify against his former friend and colleague.
Much more credible, said Hearn, were the other witnesses: young Conservative employees who described how Sona eagerly bragged about an elaborate plan to stymie Liberal voters, one he likened to the TV action-drama "24."
By now, the saga of the Guelph robocalls is well known. On the morning of May 2, 2011, automated phone calls were set up to target voters in Guelph — most of them Liberal supporters — with misleading instructions on where to vote.
The company that made the calls, Edmonton-based tech firm RackNine, was hired by a customer who used fake names, including the infamous "Pierre Poutine," a disposable pay-as-you-go cellphone and prepaid credit cards.
In their closing arguments, both the defence and Crown said they believe more than one person hatched the plot — a conspiratorial note that has long pervaded the robocalls narrative, and one with which Hearn clearly agreed.
"Although the evidence indicates he did not likely act alone, (Sona) was a party to the offence," he said.
"I'm also fully satisfied that he did so with clear intention to prevent and endeavour to prevent the electorate from voting."
Despite the defence's "valiant effort" to highlight inconsistencies in the testimony, Sona's former colleagues — with the exception of Prescott — were "candid, forthright and consistent," and telling the truth, Hearn decided.
"The balance of the evidence which I do accept is sufficient to establish beyond a reasonable doubt that Mr. Sona is guilty," he said. Sona's "apparent arrogance and self importance" were his downfall, he added.
Outside court, Sona's lawyer Norm Boxall described his client as being "very disappointed" by the ruling. Boxall said a decision on whether to appeal wouldn't be made immediately.
Sona, who faces a maximum penalty of five years in prison and a $5,000 fine, returns to court for a sentencing hearing on Oct. 17, at which point "we'll be making very forceful submissions on sentencing," said Crown attorney Croft Michaelson — a warning, perhaps, to political operatives of all stripes watching in Ottawa.
"If there was any political party that actively participated in a scheme to endeavour to prevent electors from voting ... that would be very serious conduct," Michaelson said.
"Anyone who engages in this kind of conduct, where there's evidence that they endeavoured to prevent electors from voting, I think based on what took place in court today and what you've seen us do in relation to this case, I would expect they would be prosecuted."
Conservative party spokesman Cory Hann was quick to react to the verdict, issuing a statement within minutes of the decision.
"Voter suppression is extremely serious and those responsible should be prosecuted to the full extent of the law. That's why we reached out to Elections Canada when we heard of wrongdoing in Guelph and did all we could to assist them," Hann said.
"As we've said all along, the Conservative party ran a clean and ethical campaign."
Not so fast, noted the equally swift Council of Canadians, which has long alleged that the Conservatives are no strangers to electoral meddling.
"We have a few clues about one minor player but we still don't have the ringleaders," said Maude Barlow, the council's national chairperson.
"Remember, this didn't just happen in Guelph."
Last year, the council backed a court challenge of election results in six ridings. Federal Court Judge Richard Mosley concluded that the Conservative party's massive voter identification database, the Constituent Information Management System, or CIMS, was "the most likely source" of information used to make misleading robocalls to electors "in ridings across the country."
Mosley nevertheless refused to annul the results in the six ridings.
However, Yves Cote, commissioner of Canada elections, dismissed the nationwide conspiracy theory in April, after wrapping up a three-year investigation into some 2,500 complaints about robocalls from voters in 261 ridings.
Cote concluded there was insufficient evidence to believe an offence was committed in any riding other than Guelph.
Hearn's ruling marks the second time a judge has concluded more than one person was involved in the robocall scam and that CIMS was used to carry it off, said NDP democratic reform critic Craig Scott.
At a minimum, that should prompt Cote's investigators to re-open their probe into the Guelph case, said Scott, who also called for a public inquiry to determine whether there was cross-country voter suppression scheme at play.
"I think this is sufficiently damaging to our electoral system, our democracy, to have a crime of this sort proven in court," he said in an interview.
"I think we have to get to the bottom of it."
Liberal Leader Justin Trudeau said the judge's comments were cause for concern, adding his party will revisit the issue as the 2015 federal election gets closer.
"There's an awful lot of questions to be answered about who, and how much of a co-ordinated approach was this by the Conservative party," Trudeau said in Saskatoon.
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