PETERBOROUGH, Ont. -- Dean Del Mastro insisted Thursday he never sent or received a series of emails considered central to the Elections Act charges against him, casting doubt on the foundation of the prosecution's case.

On the witness stand for his first full day of testimony, the now Independent MP -- once a political pitbull who defended the Conservatives from partisan claims of dirty electoral tricks -- repeatedly suggested a portion of digital communications provided to investigators by the Crown's key witness were fake.

"So that email chain...you just say you didn't write those, you didn't receive those?" asked defence lawyer Jeffrey Ayotte.

"This electronic discussion did not take place," Del Mastro replied. "I did not write them, I did not receive them."

The emails in question came from the laptop of Frank Hall, president of Holinshed Research, the now-defunct data-consulting firm whose alleged services lie at the centre of the case.

Hall has said his company provided hundreds of hours of voter-ID calling for Del Mastro's campaign -- a claim supported by emails between himself and Del Mastro that were found on his computer by investigators.

Del Mastro, however, testified that he rebuffed Hall's efforts to get him to buy Holinshed's voter ID services, and denied ever receiving or sending the emails in question.

He also said he was not familiar with spreadsheets attached to some of those emails, which Hall said he had been sending regularly to Del Mastro's campaign as part of the voter identification services.

"At no point did I discuss a voter ID package for the campaign with Frank Hall. At no point," said Del Mastro.

Del Mastro is charged with overspending during the 2008 federal election campaign, failing to report a personal contribution of $21,000 to his own campaign and knowingly submitting a falsified document. He has denied all the allegations.

He did acknowledge that he had discussions with Hall about new riding mapping software that was under development by Holinshed to identify the political leanings of would-be voters in a particular constituency.

Del Mastro said he told Hall he was interested in buying the software -- called GeoVote -- and gave Holinshed a $21,000 personal cheque in 2008 as a deposit when Hall said he needed one.

The software was to be jointly owned by the Peterborough Conservative Electoral District Association and Del Mastro's constituency office.

The Crown, however, alleges that the cheque was actually to pay for voter ID calls, putting Del Mastro over the limit both for personal contributions and overall campaign spending.

The prosecution has also pointed out that while the cheque was dated for August, prior to the election period, Del Mastro's account only had sufficient funds to cover it in October, when it was cashed.

Del Mastro said he's never concerned about his cheques clearing because his account is tied to a line of credit.

"The Royal Bank does not bounce my cheques," he said, adding that a financial adviser could have called his wife, who shares the account, and asked her to deposit sufficient funds before the cheque cleared.

Questionable dates on key documents have been a significant issue in the trial as the Crown has further alleged Del Mastro tried to use backdated invoices to make it appear Holinshed had only charged his campaign a fraction of the overall cost of its services during the election period -- an allegation the MP firmly denied.

"I never asked (Hall) to do that," Del Mastro said, adding he had no control over the dates Hall printed on Holinshed contracts.

The only campaign-related contract the MP had with Holinshed was for the firm to conduct a portion of get-out-the-vote calls on election day -- a service which was declared on Del Mastro's election expenses.

"At no point -- and I want to be emphatic on this -- at no point was our campaign over its spending limit," he said.

Later Thursday, Del Mastro found himself on the defensive when Crown prosecutor Tom Lemon began his cross-examination by focusing on the dates of the MP's GeoVote contract with Holinshed.

The document was created by Hall in June 2008 but Del Mastro said he signed and dated it for December that year.

Del Mastro has told the court that GeoVote never ended up working for his campaign and that it became the subject of a small claims court case Hall tried to bring against him that was ultimately abandoned.

He said he only signed the GeoVote contract in December 2008 because Holinshed's terms of service had to be revised multiple times.

"So it's common business practice to enter into a business agreement with services that you're not clear a party has agreed upon?" Lemon asked, in a series of aggressive questions on the subject.

"I was certain that there was an understanding," Del Mastro said. "I provided a cheque because there was a level of trust there."

"That doesn't explain why you dated the June contract for December 2008," Lemon said.

Del Mastro's testimony continues Friday.