The donations were part of an alleged scheme to skirt political financing rules by concealing the fact they were made by a corporate donor.
"It sounded like a good deal," said one contributor whose name was blacked out in the documents released this week.
Another contributor was asked "if friends or family could do this."
The evidence forms part of an ongoing investigation by the Office of the Commissioner of Canada Elections into the activities of Deltro Electric Inc. and its president, David Del Mastro.
Former Conservative MP Dean Del Mastro, who now sits as an Independent, is not a subject of the investigation. No charges have been laid in the case, and the allegations have not been tested in court.
Following legal pressure brought by The Ottawa Citizen, the newspaper that broke the story in 2012, heavily redacted court documents related to a search warrant request were released this week. Investigators, backed by a technical unit of the RCMP, searched the offices of Deltro in Mississauga, Ont., last fall.
Names of those they spoke to were blacked out in the documents for fear of "potential intimidation" by those who "may be charged in the future."
"I believe...that Deltro Electric Ltd., David Del Mastro and/or his staff, encouraged employees or former employees to make donations that would be reimbursed by Deltro Electric and to enlist friends or family to make similar donations," wrote investigator Ronald Lamothe.
Under the Canada Elections Act, it is illegal to make a donation under someone else's name, and corporations are barred from making political contributions.
In addition to receiving a $50 bonus with the reimbursement, those who allegedly participated in the scheme could also apply for a tax credit. Investigators estimated the credit at $558 per person.
Although notations on the cheques specifically earmarked the money for the MP's re-election campaign, some of it was directed to the Conservative electoral district association in Peterborough.
The Citizen previously quoted two anonymous sources, who provided copies of cheques, alleging they had been asked to donate to the MP's campaign in exchange for the reimbursement.
It is not known whether they are the same two people who later spoke to investigators. Details of an interview with a third person were heavily redacted, but that individual appeared to bolster the investigators' view that the firm, Del Mastro and potentially others encouraged the donations.
Bank documents secured through a previous warrant showed that 22 people who showed up as contributors to the MP's campaign or to the Conservative riding association also received cheques of $1,050.
David Del Mastro did not return a call placed to Deltro Electric. He told Lamothe in the summer of 2012 that he did nothing wrong. His lawyer later told Lamothe that Del Mastro would not co-operate voluntarily with the investigation, unless he was provided with "immunity."
Scott Fenton, a lawyer representing David Del Mastro, told the Citizen in an email Tuesday that "Mr. Del Mastro denies having being involved in any breaches of the Elections Act."
Dean Del Mastro declined to comment.
The MP is facing four charges under the Canada Elections Act for allegedly exceeding his 2008 campaign spending limit, and submitting allegedly misleading documents to Elections Canada.
Del Mastro has said he is anxious to fight the charges when they reach a courtroom in June.
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