Liberal Mac Harb, Tory Sen. Mike Duffy and Patrick Brazeau are seen in this combination file photo. QMI Agency/REUTERS

OTTAWA - An outside auditing firm will probe the "residency declarations and related expenses" of three sitting senators, including Patrick Brazeau who was released from a Quebec jail Friday.

Sen. David Tkachuk, chair of the Standing Senate Committee on Internal Economy, announced Friday that Deloitte will review and report the finances of former Tory Brazeau, Liberal Mac Harb and Tory Sen. Mike Duffy.

All three senators are under review for claiming living allowance costs for a "second residence" in the Ottawa region, when it appears they do not reside elsewhere.

Brazeau was kicked out of the Conservative caucus on Thursday following his arrest at his Gatineau, Que., residence.