Conservative MP Dean Del Mastro, the party's lead spokesman on the robocalls election controversy, faces allegations of his own over his spending in the 2008 federal election.

The member for Peterborough, Ont. is reportedly under investigation for spending too much money in the campaign almost four years ago. Invoices and cheques filed in a small claims court case show $21,000 spent on polling and get-out-the-vote services, apparently paid for with a personal cheque from Del Mastro, that is unaccounted for.

Del Mastro says he absolutely did not overspend to get elected and that the expenses he filed with Elections Canada have been audited.

No charges have been filed, and the allegations from the court documents have not been tested in court. Elections Canada won't confirm whether they are investigating, as is their policy.

Under the Elections Act, penalties for exceeding personal contribution limits or going over the campaign spending limit are fines of up to $5,000 or up to five years in prison.

Opposition MPs say Del Mastro's responses so far don't clear up the mystery surrounding the records. Here are five questions raised by his 2008 campaign spending:

1. Was he reimbursed for the $21,000 personal cheque?

Federal election spending laws say candidates can contribute $2,100 to their campaigns, a tenth of the amount in question. Del Mastro says his campaign or his riding association reimbursed him for any election expenses, but records on the website of Elections Canada show no sign of a repayment that big. The records show the campaign reimbursed Del Mastro a total of $437.54 for his 2008 run. Likewise, the expenses filed by the riding association show $96,670 in transfers to Del Mastro's campaign, but none to him.

2. Why isn't the $21,000 paid to Holinshed Research Group listed in the election return?

After a 2009 falling-out over a contract with Del Mastro, Frank Hall, president of Holinshed Research Group, filed a suit in small claims court. The claim was dismissed as abandoned June 8, 2011, meaning Hall let it lapse. But the records he filed in the claim are still available. They show a $21,000 invoice, as well as the personal cheque from Del Mastro. The Sept. 14, 2008 invoice lists 630 hours of voter identification phone calls, plus election day get-out-the-vote calls. But the Elections Canada return lists only two Holinshed expenses: one for $10,000, categorized in a miscellaneous "amounts not included in election expenses" category, and another for $1,575 for election surveys or other research. UPDATE: Del Mastro says the $21,000 was a quote for potential services, not an invoice, and doesn't reflect work done for his campaign. The campaign was set to pay in two installments: one a $10,000 cheque and the other an $11,000 cheque. Elections Canada records show Holinshed refunded $10,000 and Del Mastro's campaign put a stop on the $11,000 payment.

3. What happened to the other $11,000?

While there's a $10,000 expense for Holinshed listed in the campaign costs in Elections Canada's records, if that comes from the $21,000 quote, Del Mastro's campaign has up to another $11,000 unaccounted for.

4. How does the $21,000 fit in under the spending limit?

Del Mastro's campaign spending limit was $92,566.79. The expenses he submitted to Elections Canada show he spent $90,987.52 or 98.29 per cent of his cap (before the election agency reviewed and got more detailed information from him, records showed he spent $91,770.80, or 99.14 per cent of his cap). Elections Canada records suggest that if the $21,000 invoice is included, he would have exceeded the limit. Del Mastro did not explain the additional $21,000.

5. What happened to Holinshed?

The Ottawa-based research and polling company appears to be out of business, with its website out of service and its phone disconnected. The firm did work for at least 10 federal Conservative candidates in the 2008 election, and worked with Ontario Progressive Conservatives as well. As the CBC's Kady O'Malley pointed out last fall, Holinshed got $125,000 from the federal government to develop GeoVote, a voter ID system. The cash was part of the Canada Economic Action Plan. The project website says the money was to develop "the firm's flagship application GeoVote used in support of election campaigns and data management used in preparation for upcoming elections." It also seems to be the only political polling firm to have received stimulus money.