Andrew Prescott was the Conservatives' deputy campaign manager in Guelph, Ont., where supporters of other candidates complained they received misleading phone calls directing them to the wrong polling station.
Prescott has a written guarantee "the Crown has no intention" of charging him in connection with the misleading phone calls, according to a source close to the case.
The calls were directed at non-Conservative Party supporters.
The agreement says the Crown is interested in Prescott as a witness and not as an accused. It was reached sometime in December.
Michael Sona, 25, is the only person charged in the robocalls scandal. A former staffer to Conservative MP Rob Moore, he was candidate Marty Burke's director of communications during the campaign. Sona has repeatedly denied any involvement and says his name was leaked to the media by someone in the Conservative Party because of a previous scandal.
Sona was accused during the campaign of grabbing for a ballot box at the University of Guelph, an action he denies.
Prescott's lawyer, Matthew Stanley, said he couldn't comment on whether his client has an agreement with the Crown.
Prescott, who has made only rare public comments on the matter, said in October 2012 that he appreciates the support of family and friends like Sona "who know I was not involved."
"I respect the voters and democracy far too much to participate in any disgusting dirty tricks like this," Prescott said in a written statement more than a year ago.
2 robocalls accounts
Prescott's name has come up in some of the court filings made by investigators from Elections Canada, although he has so far declined to be interviewed by them.
Prescott, who was paid a $1,000 stipend for his work on the campaign, including IT services, was the main contact with RackNine, the company whose services were used to make the illicit calls.
All political parties use robocalls, or automated calls, to reach voters. Robocalls are regulated but not illegal. The calls at the heart of the investigation in Guelph were illegal because Elections Canada believes they were meant to interfere with some voters' right to cast their ballots.
Burke's campaign used RackNine to make legitimate robocalls through Prescott's account. The misleading calls were made using a separate account, although Al Mathews, the Elections Canada investigator leading the probe, has traced the two accounts to the same computer.
In one instance, Mathews alleges in an affidavit filed in court, the account assigned to Prescott and the account used to make the misleading calls both signed into RackNine in a single web session minutes apart.
Pierre Poutine used burner phone
Mathews says in the affidavit that he has an email showing Prescott sent the campaign's RackNine contact information to Sona and campaign manager Ken Morgan on April 30, 2011, one day before the mystery robocaller programmed the misleading calls.
It's not clear why Prescott sent the information to Sona and Morgan — there is no mention of an emailed request for the information in the court documents.
Later on April 30, somebody using the pseudonym Pierre Jones set up a RackNine account using a private phone number that company president Matt Meier only provides to clients.
The mysterious caller also set up a PayPal account using prepaid, or vanilla, credit cards, and bought a disposable, or burner, cellphone. The cellphone account was set up under the name Pierre Poutine.
Sona is scheduled to be in court June 2 for either a preliminary hearing or, if he forgoes the preliminary hearing, a trial.
Croft Michaelson, the Crown assigned to Sona's case, said he won't comment on cases before the courts.
Sona's lawyer wasn't immediately available to comment.
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