At least five people were allegedly involved in a telephone conversation that led to an election-related police investigation into Ottawa city Coun. Tim Tierney, sources tell CBC News.

As reported earlier this week, Ontario Provincial Police are investigating a conversation that allegedly took place behind closed doors at the city's elections office moments before the 2 p.m. deadline for candidates to register on July 27.

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Michael Schurter, Tierney's only rival for the Beacon Hill-Cyrville council seat, has said the subject of that conversation led him to make an official complaint, but refused to elaborate on what was discussed.

However, a number of sources confirmed to CBC Tierney tried to convince Schurter not to run against him, and allegedly promised to make a donation to a local food bank if Schurter dropped out of the race.

Under the Municipal Elections Act, it's an offence to offer a candidate an inducement to drop out of an election.

Before a library board meeting Tuesday, Tierney said he would not be commenting on the issue.

"There is a process that is in place, and again at the advice of my lawyer, we will let that play out at this time," the councillor said.

Investigation hinges on call

In the office at the time of the alleged call were Schurter, who threw his hat into the ring at the last minute to run against the two-term incumbent, Schurter's campaign manager Justin McAuley and a city election official.

According to sources, while in the office, Schurter received a call from Jeremy Wittet, who is known to both Tierney and Schurter. Wittet, who did not reply to a request for comment, also works for outgoing Innes Coun. Jody Mitic, who is on leave for health reasons.

Sources said once he had Schurter on the phone, Wittet then patched Tierney into the call, some of which could be heard on a speaker phone. Sources said Wittet stayed on the line, but it was unclear if any others were also listening in.

Michael Schurter said he contacted police after a phone call with incumbent Tim Tierney. (CBC)

OPP interviewing witnesses

Schurter filed an official complaint with Ottawa police sometime after the alleged phone call.

Because Tierney sits on the Ottawa Police Services Board, the case was forwarded to the OPP to avoid any perception of a conflict of interest.

Last Friday, Tierney recused himself from the OPS board, presumably because it would be awkward for a board member to be under investigation by the police force it oversees.

Sources told CBC that OPP investigators have interviewed a number of people connected with the investigation including Schurter, McAuley and city officials. Tierney would not say whether he's been interviewed by the OPP.