The party's internal procedure has been halted with gardaí taking up the case.
The Sinn Fein Leader is characterising the complaint made against Laois Offaly TD Brian Stanley, which has been passed on to gardaí, as "serious".
Mr Stanley has resigned from the party claiming he was unfairly treated by an inquiry into a complaint against him.
Mary Lou McDonald says the internal process has now been suspended - Deputy Stanley says the process was seriously flawed.
Speaking with Will Faulkner on Midlands Today, she says she couldn't outline the details of the complaint:
Gardai Praise Safety Organisation For Hard Work
Westmeath Councillor Calls For Compromise On Housing Development
Offaly Councillor Proposes Livestreamed Local Authority Meetings
Revenue Seize Over €570k In Contraband
Westmeath Volunteers Recognised At Water Safety Awards
Westmeath Hospital Among Top Earners Of Public Health Funds
Calls For Accountability Over State Covered Tax Errors
Government To Support Workers Affected By Fastway Receivership - Peter Burke
Major Oil Spill In Offaly
Growing Industry Driving Rise In Property Prices - Laois Auctioneer
Half A Million Granted For Midlands Outdoor Recreation Projects
New Objection To Midlands Hospice Site In Offaly
Developers To Address Oireachtas On Housing Challenges
Westmeath Residents Move Against Major Housing Development
Median House Prices Rise In Midlands
Literary Festival Kicks Off In Laois Tomorrow
New Entrance To Laois Shopping Centre Gets Green Light
Midlands Winners For Family Carer Of The Year Announced
INTO Survey Reveals Job Vacancies In Over Half Of Special Schools
Offaly Mother Raises Almost €2k for Down Syndrome Ireland