The city of Toronto's integrity commissioner has launched an investigation into Etobicoke councillor Justin Di Ciano's ties to a local developer.

CBC News has learned the investigation centres on allegations the councillor benefited "financially and politically" from developer Dunpar Homes Ltd.

Coun. Di Ciano, who represents Ward 5, Etobicoke-Lakeshore, has had both personal and business ties to Dunpar, as first reported by CBC News in May. He and fellow Etobicoke councillor Mark Grimes pushed for changes to a planning report that ended up benefiting Dunpar.

Allegation: Di Ciano bought new home from Dunpar for 'well below market value'

The complaint to the integrity commissioner was filed by Etobicoke resident Malcolm Strachan.

While none of the allegations have been proven, Strachan raises seven issues he wants investigated.

Among them, Strachan alleges Di Ciano has bought two newly built homes from Dunpar. The second purchase was in 2009, when according to the complaint, Di Ciano "was known to be a candidate in the ensuing election," and Di Ciano allegedly paid "tens of thousands of dollars less" than his neighbours. Land registry records obtained by CBC News show Di Ciano paid $434,149 for the newly built townhome.

In his affidavit to the integrity commissioner Strachan writes: "Giving [Di Ciano] the ability to purchase the property well below market value is tantamount to a gift and is a violation of Section IV of the Code [of Conduct]."

Land registry records indicate his immediate neighbours on either side paid between $32,000 and $66,000 more.

CBC News has learned several Dunpar executives also bought homes in the same complex and also paid less than their neighbours.

In May, when CBC News first raised the issue, Di Ciano said, "I paid what they asked me to pay." In a subsequent email, his lawyer threatened to sue CBC News, adding Di Ciano paid "tens of thousands" of dollars to upgrade paint and tiles himself that wasn't reflected in the purchase price from Dunpar.

The complaint also alleges that in May, when Di Ciano pushed for the rezoning changes that benefited Dunpar, he was involved in an ongoing libel lawsuit against Etobicoke businessman Dean French.

Court documents obtained by CBC News show Di Ciano wanted $100,000 in damages, claiming French libelled him and caused him to lose the 2010 municipal election.

French had publicly accused Di Ciano of having personal ties to Dunpar and its owner John Zanini. French had also led a local residents' group that fought the height of a proposed Dunpar development in the Kingsway neighbourhood of Etobicoke. Dunpar eventually won the costly battle at the Ontario Municipal Board.

In his affidavit to the integrity commissioner, Strachan notes that Di Ciano was questioned by French's lawyer as part of the civil proceeding. A transcript of the hearing, obtained by CBC News, shows Di Ciano refused to answer when asked if Dunpar owner Zanini was paying his legal bills. Di Ciano also refused to answer if he was paying his own legal bills. Di Ciano's lawyer had advised him not to answer the questions.

In June, days after CBC news reports detailed Di Ciano's past ties to Dunpar, the lawsuit was dropped. The case was supposed to go to trial weeks later. CBC News asked Di Ciano why the lawsuit was withdrawn but he declined to answer.

Developer's employees allegedly canvassed for councillor

The complaint made by Strachan also alleges "Dunpar staff canvassed Dunpar built homes on behalf of the Di Ciano campaign" in both the 2010 and 2014 municipal campaigns. Di Ciano and Zanini have a long standing friendship.

In his affidavit to the integrity commissioner, Strachan alleges "Councillor Di Ciano has a long and close relationship with Dunpar. It has been a relationship that has been both financially and politically rewarding for him. It is therefore my contention that he was in contravention of the [Code of Conduct] Act by voting to support the rezoning of the land on Judson Street, a rezoning that stands to profit Dunpar."

In addition to the complaints made by Strachan, CBC News has learned that prior to becoming a councillor, Di Ciano was a guest on a number of occasions at Zanini's Scottsdale, Arizona vacation property. Earlier this year, Di Ciano purchased his own property in Scottsdale.

Di Ciano declined to answer questions about the allegations contained in the complaint, or his visits to Arizona with Zanini. In an email to CBC News he wrote: "I do not believe that I have contravened the City's Code of Conduct (or the Municipal Conflict of Interest Act for that matter), and am taking that position in responding to the complaint with the Integrity Commissioner."

John Lancaster can be reached at john.lancaster@cbc.ca or 416-205-7538