PETERBOROUGH, Ont. -- A Crown lawyer at the trial of a member of Parliament charged under the Canada Elections Act has told court the case might be considered unusual.

Tom Lemon says a large documentary record and several witnesses will be involved in the trial of Dean Del Mastro, which got underway in Peterborough, Ont., today.

Del Mastro has pleaded not guilty to charges of overspending during the 2008 federal election campaign and failing to report a personal contribution of $21,000 to his own campaign.

Elections Canada also alleges Del Mastro tried to cover up his overspending by knowingly submitting a falsified document. He denies any wrongdoing.

Del Mastro was once the Harper government's point man on defending the Conservatives against voter fraud allegations.

But Stephen Harper's former parliamentary secretary is now sitting as an independent in the House of Commons pending the outcome of the case.

Richard McCarthy, Del Mastro's official agent for the 2008 campaign, is being tried at the same time on three charges, including "incurring election expenses in an amount more than the election expenses limit."

Del Mastro stands accused of paying Ottawa-based Holinshed Research $21,000 for consulting work on his 2008 campaign -- an amount that would have put him over the maximum $2,100 candidates can contribute to their own campaigns.

It's alleged he paid Holinshed using a personal cheque from an account he shares with his wife, but failed to include the amount in his campaign financial report.

That report listed Holinshed as having been paid $1,575.

Investigators have also claimed that a false document was filed by the Del Mastro campaign, indicating that $10,000 of the $21,000 paid from the Del Mastro chequing account had been refunded by Holinshed.

"The Crown's theory is that the transactions described above amounted to Mr. Del Mastro and Mr. McCarthy incurring a $21,000 election expense from Holinshed," said Lemon.

"Mr. Del Mastro paying the expense with his own funds, according to the Crown's theory, facilitated the concealment and misreporting of the expenses."