Sona, who worked on the local Conservative campaign in Guelph leading up to the 2011 federal election, is charged with preventing or trying to prevent an elector from voting.
The Crown alleges that Sona spearheaded a scheme to use robocalls to mislead non-Conservative voters in Guelph on the day of the election.
More than 6,700 phone numbers received automated calls, purporting to be from Elections Canada, with incorrect information about poll locations.
Andrew Prescott, a colleague of Sona's who was acting campaign manager for the Conservative candidate Marty Burke, has been offered immunity in return for his testimony
Prescott says he had a good friendship with Sona until recently.
"We understood one another," he said.
Court heard on Tuesday that Prescott had an account with RackNine, the company that was hired to make the automated calls in Guelph.
It was another account, created with the fake name Pierre Jones, that created the fraudulent campaign.
Both accounts logged into the RackNine website around the same time from Burke's campaign office.
On Tuesday, RackNine owner Matt Meier testified that he alerted Prescott to an Elections Canada investigation into the calls days after he was first approached by investigators.
Asked why he contacted Prescott, Meier said Prescott's name had come up in his talks with Elections Canada and he was "curious" to see if he'd been contacted too.
Prescott said he knew nothing about the calls, Meier testified.