OTTAWA -- After a three-year investigation into almost 2,500 complaints in 261 ridings across Canada, the robocall scandal comes down to a solitary trial of one junior Conservative campaign staffer in a single southwestern Ontario riding.

Michael Sona's trial is scheduled to begin Monday.

Sona, 25, is charged with "wilfully preventing or endeavouring to prevent an elector from voting," having allegedly orchestrated an automated phone message scam to send non-Conservative voters in Guelph to the wrong polling stations during the 2011 election.

Sona, who was communications director for Guelph Conservative candidate Marty Burke, is the only person charged in the robocall affair.

He maintains he's been scapegoated by his former party to protect those higher up the food chain who orchestrated what he believes was a conspiracy to suppress non-Tory votes that went well beyond Guelph.

"I had no involvement in this. At all," Sona told Huffington Post Canada in a pre-trial interview last week.

Sona declined to speak to The Canadian Press, as did his lawyer, Norman Boxall.

However, when Sona was first charged a year ago, Boxall argued that a public inquiry was needed to get to the bottom of the robocall affair, "rather than a charge laid against a single individual who held a junior position on a single campaign and who clearly lacked the resources and access to the data required to make the robocalls."

From the outset, Guelph has been the epicentre of the robocall scandal. The commissioner of elections, Yves Cote, began an investigation into complaints about misleading automated calls in that city shortly after the election on May 2, 2011.

But when news reports in February 2012 first revealed details of the scam used in Guelph -- a complicated scheme involving someone going by the pseudonym Pierre Poutine using a disposable cellphone to purchase the services of the Conservative party's automated phone service, RackNine -- they triggered a flood of more than 40,000 complaints to Elections Canada from all across the country.

The notion of a nationwide voter suppression conspiracy gained credence last year from Federal Court Judge Richard Mosley, who heard a challenge from a group of voters seeking to overturn the election results in six ridings.

Mosley concluded that misleading robocalls were made "to electors in ridings across the country ... and that the purpose of those calls was to suppress the votes of electors."

Moreover, he said the "most likely source" of voter information used to make the calls was the Conservative party's massive database, known as the Constituent Information Management System, or CIMS.

Nevertheless, Mosley said there was insufficient evidence to prove the fraud actually succeeded in altering the outcome of the election, and refused to annul the results in the six ridings.

In April of this year, Cote burst the conspiracy theory balloon, announcing that a thorough investigation had not turned up sufficient evidence to believe an offence was committed in any riding other than Guelph.

Of the 40,000 people who contacted Elections Canada about robocalls, Cote said only 2,448 complaints in 261 ridings turned out to be from individuals who actually claimed to have received misleading or harassing robocalls during the 2011 campaign. The rest were from people expressing general concern about the robocall affair.

When his investigators spoke with robocall recipients, they found in most instances they "could provide only vague and incomplete information."

Only three could provide an audio recording or transcript of the allegedly misleading robocalls. Two were deemed "innocuous" by investigators and the third appeared to be a case of a local campaign providing incorrect poll information to one of its own supporters.

Cote's report turned the robocall spotlight back on Guelph and, more specifically, on Sona, who calls Elections Canada's broader investigation "an absolute farce."

Sona told Huffington Post Canada he's confident the trial will exonerate him.

But one of his former Guelph campaign colleagues, Andrew Prescott, has reportedly agreed to testify against Sona and Ken Morgan, the manager of the Guelph Tory campaign, in exchange for immunity from prosecution.

Morgan moved to Kuwait shortly after the 2011 campaign and, according to court documents, has refused to speak to Elections Canada investigators about the robocall affair. He has not been charged with any offence.

A number of junior Conservative staffers on Parliament Hill are also likely to be called to testify. Court documents show six staffers told investigators -- with some prompting by Conservative party lawyer Arthur Hamilton -- that Sona boasted to them shortly after the 2011 election about orchestrating the robocall scam in Guelph.

However, Sona has produced travel documents showing he was actually on vacation in Aruba at the time he was supposedly bragging to the staffers.

If he is found guilty, Sona faces up to five years in prison and fines of up to $5,000.