Twenty-five senators have either refused to prove to CBC News that they live where they claim to or haven't responded to questions, as a senate probe into their residency and allowances goes on.

CBC's James Cudmore asked each one of 104 sitting senators to answer:

Where they live.

Where they hold a driver's licence and health card.

Where they pay taxes.

Where they vote.

As of Tuesday, 5 p.m. ET, 96 senators had responded to the CBC's queries.

Once contacted, 17 senators simply refused to provide the information requested. Sixteen of those senators were Conservative, and 15 were appointed by Prime Minister Stephen Harper. Among those who refused:

Conservative Donald Oliver, appointed by then-prime minister Brian Mulroney.

Former broadcaster Pamela Wallin.

Former broadcaster Mike Duffy.

Hockey legend Jacques Demers.

Former Quebec Conservative campaign co-chair Suzanne Fortin-Duplessis.

Former N.W.T. premier Dennis Patterson.

Former New Brunswick Conservative cabinet minister Rose-May Poirier

Former Montreal Canadian Alliance and later Action Démocratique du Québec organizer Leo Housakos.

Senators respond After CBC News published this story, another six senators responded to James Cudmore's questions. Senator Leo Housakos says he lives in Quebec and holds a Quebec driver's licence and health card. Senator Tobias Enverga says he lives in Ontario and holds an Ontario driver's licence and health card. Senator Jacques Demers says he lives in Quebec and holds a Quebec driver's licence and health card. Senator Nancy Greene Raine says she lives in British Columbia and holds a B.C. driver's licence and health card. Senator Lynn Beyak says she lives in Ontario and holds an Ontario driver's licence and health card. Senator David Braley says he lives in Ontario and holds an Ontario driver's licence and health card.

A further six Conservatives have yet to respond at all. All of those are Harper appointees, including:

Larry Smith, the former head of the Canadian Football League, who was twice appointed to the Senate, the second time after he resigned from the Senate to run for the House of Commons and lost.

Irving Gerstein, a Conservative party fundraiser.

That means a total of 21 Conservative senators appointed by Stephen Harper have either refused or not furnished the residency data to CBC News.

One Liberal refused

Two of 36 Liberal senators haven't responded to the request. Trudeau appointee Pierre De Bané refused to turn over the information, but told CBC News he lives in Ottawa — not in the Quebec riding he was appointed to represent. De Bané says he doesn't claim the living allowance.

Getting answers There are 104 senators right now. Most — 96 — responded to questions from CBC News: 58 of 64 Conservatives, 34 of 36 Liberals, and four independent senators. Of the 96 who answered, 17 refused outright to back up their response by saying whether they hold the correct driver's licence and health card. All but one were Conservative, and all but one of the Conservative refusals were from senators appointed by Harper. Eight senators have yet to respond: six Conservatives and two Liberals.

Liberal Senator Mac Harb, who is under fire now for racking up Senate travel and living expenses, didn't respond at all. Harb was an Ottawa city councillor from 1985-1988, then represented Ottawa Centre — the riding in which Parliament Hill sits — as a member of Parliament until he was appointed to the Senate in 2003.

Two Conservative senators who sit on the Senate committee reviewing the residency and expenses of senators have also refused to disclose key residency issues to CBC News.

Despite repeated requests over two weeks, Smith and his Senate caucus colleague Claude Carignan have refused to reveal in which province each holds a driver's licence and health card, pays provincial income tax, and votes. The other 13 members of the committee have provided that information to the CBC, including the seven other Conservatives.

Five senators are expected to be called before the Senate committee auditing housing allowances to answer more questions:

Patrick Brazeau, appointed from Quebec.

Mike Duffy, appointed from P.E.I.

Mac Harb, appointed from Ontario.

Dennis Patterson, appointed from Nunavut.

Pamela Wallin, appointed from Saskatchewan.

Duffy to repay expenses

Patterson refused to answer questions from reporters Tuesday as he left a committee on Parliament Hill. He said he's co-operating with the review process.

Last week, Duffy told CBC News that he would pay back the expenses he'd claimed for his housing because questions about the issue were distracting people from his work. Wallin has reportedly decided to do the same.

Both Liberal and Conservative leaders in the Senate have said they expect anyone who can't back up their expense claims to repay the money.

Duffy is the only federal politician in P.E.I. who does not receive a special residents-only tax break. According to tax information obtained by the CBC, all three other senators, and four elected MPs, receive the provincial credit.

Senator Patrick Brazeau, who is also under scrutiny for his expenses, did respond to questions and provided the information requested.

Brazeau lists his primary residence as Maniwaki, even though the address listed on his driver's licence shows he lives in Gatineau, the city across the river from Parliament Hill.

Brazeau currently faces charges of assault and sexual assault in an unrelated matter.