The Senate has asked for an outside audit of three senators’ housing expenses after their residency claims came under scrutiny.

Among them is Sen. Patrick Brazeau, who was criminally charged in connection with an alleged domestic violence incident and kicked out the Conservative caucus.

The expenses of Conservative Sen. Mike Duffy and Liberal Sen. Mac Harb will also be audited.

The accounting firm Deloitte will review the senators’ claims about where they primarily live and the housing allowances they’ve collected for accommodations closer to Ottawa.

The Senate has already asked all members of the Red Chamber to prove where they live by submitting copies of their drivers’ licences, health cards and tax returns.

Committee chair Sen. David Tkachuk and deputy chair Sen. George Furey also said Friday that they are seeking a legal opinion about Duffy's residency.

Duffy has been under fire for collecting a taxpayer-subsidized housing allowance by claiming his home in Cavendish, P.E.I., as his primary residence, even though he has lived in the Ottawa area for decades.

Senators can claim $21,000 annually in housing and meal expenses if their primary address is more than 100 kilometres from Ottawa.

It was recently revealed that Duffy wasn’t on the voters’ list in his home province in 2011, but voted in the Ontario provincial election that year. He also had to apply for a new P.E.I. health card -- an application his office tried to expedite ahead of a Jan. 31 deadline requiring all senators to provide proof of residence.

In a statement Friday, Duffy repeated that he has done nothing wrong.

"As a Prince Edward Islander, born and bred, I am proud to represent my province and its interests in the Senate of Canada," he said.

"I represent taxpayers with care, and Canadians know I would never do anything to betray the public trust. I have a home in Prince Edward Island as required by law. I will have no further comment until this review is complete."

Brazeau has also denied any wrongdoing for listing his father’s Maniwaki, Que., home as his primary residence and collecting a housing allowance, even though he lives in a house in Gatineau, a short drive from Parliament Hill.

Brazeau was arrested at that Gatineau home Thursday morning after an alleged domestic violence call. He was charged Friday with assault and sexual assault and will be placed on a leave of absence from the Senate as a result.

Harb, a longtime Ottawa resident and former MP, has been questioned for claiming expenses for a secondary residence in the city.

With files from The Canadian Press