The Crown says it believes former Conservative staffer Michael Sona did not work alone in committing election fraud in 2011.

But in its closing statement in a Guelph, Ont., courtroom today, the Crown says there's ample evidence pointing to Sona as the main culprit in the misleading robocalls plot to prevent Liberal supporters from voting on election day.

Sona is accused of concocting an elaborate plot to autodial 6,700 phone numbers on the morning of the 2011 election with misleading information on where to vote in Guelph.

Crown attorney Croft Michaelson tells Justice Gary Hearn the evidence "points to more than one person" being involved.

But Michaelson insists "Sona played an instrumental role and committed one or more acts" in the scheme.

Sona, who has maintained his innocence, is charged with "wilfully preventing or endeavouring to prevent an elector from voting." He faces a maximum penalty of five years in prison.

'Compelling evidence'

Michaelson cites "compelling evidence" that Sona used the fake names Pierre Poutine and Pierre Jones to acquire untraceable prepaid credit cards and a disposable phone to cover his tracks while ordering the robocalls.

He also says the evidence of Andrew Prescott, who testified against Sona in exchange for immunity, "should probably be approached with caution."

Last week, the Crown called a number of Sona's past colleagues to testify that he had admitted to planning and pulling off the fraud.

The defence elected to not call any witnesses in Sona's defence.