An Elections Canada investigator alleges in court documents that he suspected Conservative campaign worker Michael Sona was not the only person involved in misleading robocalls to voters in Guelph, Ont.

Sona, who worked as director of communications to Marty Burke, the Conservative candidate in Guelph, is the only person charged over automated calls that directed hundreds of voters to the wrong polling station on election day in May 2011.

His defence counsel is expected in court Thursday morning in Guelph for a pretrial hearing.

In a sworn statement made public this week, Elections Canada investigator Allan Mathews described his conversations with Sona and his lawyer last year.

“In my March 2, 2012 telephone conversation with Sona, and in my conversations with his counsel, I have noted that I suspected that others were involved as well as Sona, but in each case I have been clear that I was asking Sona to provide a statement to me under warning,” Mathews alleges in an Information to Obtain a court order (ITO) he swore in May.

Witnesses who give statements under warning are told that anything they say could be used in court.

Mathews does not indicate in the ITO whether he still believes someone else was involved in the calls made by a suspect using the pseudonym “Pierre Poutine.”

But in the conclusion of the document, Mathews alleges that Sona “admitted to personal involvement while leaving some suggestion that he did not act alone.”

The ITO is subject to a publication ban that restricts the reporting of certain sections. Madam Justice Celynne Dorval ordered the ban on Monday. The Citizen is considering challenging the publication ban in court.

Mathews also refers in the ITO to comments Sona made in television interviews with CBC and Radio-Canada last fall, before he was charged for violating the Elections Act.

“Sona denied being Pierre Poutine and suggested that as a young staffer it would not have been possible for him to carry out such a vast scheme (possibly speaking of all robocall complaints, arising in over 200 [electoral districts], rather than just Guelph),” Mathews wrote.

During the interviews, Sona said he couldn’t have arranged the robocalls because he didn’t have access to the list of identified non-Conservatives contained in the Conservative Party’s voter-tracking database.

In the ITO, Mathews contradicts Sona about whether Elections Canada had ever cleared him in the robocalls case.

“Sona also said in his media interviews that Elections Canada had told him in June that they had cleared him of involvement and that our investigation was completed. These last statements are wrong,” he alleges.

In an email Wednesday, Sona’s lawyer, Norm Boxall, said, “My view is that this case should be tried in court, not in the media, and accordingly I am not commenting.”

The ITO also corrects information in an earlier court document concerning Andrew Prescott, the campaign worker who set up voice broadcasts for Burke’s campaign through RackNine, the Edmonton-based robocall company used to send the election day broadcast.