Former Conservative campaign worker Michael Sona is facing a charge under the Canada Elections Act following an investigation into mysterious robocalls that some voters in the Ontario riding of Guelph say sent them to the wrong polling station.

Sona's first appearance is set for Guelph court on May 3. He appears to be the only person facing a charge.

The charge is listed under section 491(3)d of the elections act, which prohibits preventing or trying to prevent a voter from casting a ballot. The maximum penalty is a $5,000 fine and five years in prison.

The court appearance will fall two years and one day after Canadians cast their ballots in the 2011 election, which has become known for eliciting complaints of misleading or harassing live and automated robocalls in 247 ridings across the country.

Sona was in charge of media relations for Conservative candidate Marty Burke in 2011 and was working for Conservative MP Eve Adams when his name was leaked to the media as news broke last winter of the Elections Canada investigation into the calls.

Sona says he had nothing to do with the misleading calls, which are illegal under Canadian election law.

A statement by Elections Canada confirmed the charge.

"The strong public reaction to the fraudulent telephone calls made to electors in Guelph during the May 2011 general election shows how deeply disturbed Canadians were by what happened," said Yves Côté, the commissioner of Canada Elections.

"I hope that the charge we filed today will send a strong message that such abuses under the Canada Elections Act will not be tolerated."

'An interest in seeing me take the fall'

Sona was mostly silent after his name surfaced, although he has started trying to rehabilitate his image. And while another former Guelph campaign worker named repeatedly in court documents moved from southern Ontario to Alberta, Sona has kept working in Ottawa.

Sona first fought back in a sit-down interview last fall with Evan Solomon, host of CBC News Network's Power & Politics.

Sona told Solomon that he's not going to take the fall for something he didn't do.

"All the anonymous sources in the world can point the finger at me, but I'm not going to take responsibility for something that I'm not responsible for," Sona said.

"I think that there's some people that maybe had an interest in seeing me take the fall for it."

He also said he didn't have access to the lists of voters that Elections Canada believes were used to place the calls. The agency's investigator says in court documents that it appears the party's list of non-Conservative supporters matches the list of numbers auto-dialled with the misleading message.

"You've got to take a look at the options and just say, 'You know what, what is the more realistic option here? That some then-22-year-old guy managed to co-ordinate this entire massive scheme when he didn't even have access to the data to be able to do this, or the alternative — that this was much more co-ordinated or possibly that there were people that knew how to do this, that it was being done?'"

Sona has sometimes surfaced at social events around Ottawa. He attended a party at Hy's Steakhouse following the tabling of the federal budget on March 21, an event attended every year by cabinet ministers, political staffers and reporters. A photo posted on Facebook last fall following a Halloween party featured him with a former NDP staffer.

Sona's lawyer calls for public inquiry

A statement from Sona's lawyer, Norm Boxall, says neither of them will make a public statement beyond the one distributed by email. Boxall called the charge disappointing but said it provides an opportunity for Sona to address the allegations in court instead of in the media.

"I cannot help but comment that if the government was interested in the public being fully informed and the issue of robocalls being properly addressed, a full public inquiry would be called, 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. I am confident the public agrees."

Boxall is a well-known lawyer who has served as counsel in public inquiries like the Maher Arar commission and the Air India inquiry. He is head of the Criminal Lawyers Association and past-president of the Defence Counsel Association of Ottawa.

The case in Guelph has also become known by the name Pierre Poutine, the alias used by whoever arranged for the automated calls. Elections Canada traced the calls to a burner cellphone registered to a Pierre Poutine on Separatist Street in a Quebec town.

A statement by Conservative Party spokesman Fred DeLorey said the party is pleased the investigation "has progressed to this point."

"The Conservative Party of Canada ran a clean and ethical campaign and does not tolerate such activity. The party was not involved with these calls and those that were will not play a role in any future campaign."

Party lists used for calls

Documents filed in court last year revealed the Conservative Party's lawyer, Arthur Hamilton, said the list of Guelph residents targeted by the calls matches a list of Conservative non-supporters identified by the party on April 27, just days before the election.

A CBC analysis of fraudulent calls reported across the country identified a pattern of voter identification calls and follow-up fraudulent calls made to those who said they didn't support the Conservatives.

The supporter lists were downloaded by Andrew Prescott, who handled IT for the campaign. Prescott has said he only handled supporter lists, not non-supporter lists.

Elections Canada investigator Al Mathews also said in court documents that it appeared Prescott and the fictional Pierre Poutine had logged into the same IP address within minutes of each other. An IP address is a unique locator assigned to a computer or network accessing the internet.

Prescott tweeted Tuesday evening that he was leaving for a vacation and would be out of cellphone range. He has said repeatedly on the social media site that he had nothing to do with the misleading calls.

Mathews also reported in the court documents that a staffer for former intergovernmental affairs minister Peter Penashue fingered Sona for the calls.

Penashue stepped down last month after a CBC News investigation revealed his 2011 election campaign accepted corporate donations, which are illegal in Canada.

Mathews said he interviewed Chris Crawford in March, 2012, accompanied by Hamilton. According to Mathews' court filing, Crawford told him that Sona — Crawford's former roommate — talked about "calling electors to tell them their poll location had changed" and "pretending to be Liberals" when calling non-supporters late at night.

Crawford was the Guelph campaign worker in charge of CIMS, the party's voter database, Mathews says in the court documents.

Crawford said Ken Morgan, the campaign manager for the Guelph Conservative candidate, was involved in that conversation with Sona. Morgan has since left the country, sources tell CBC News.