Tory MP Peter Bone has been accused of benefit fraud in a report in The Times newspaper.
The MP for Wellingborough and Rushden was alleged to have hidden assets belonging to his mother-in-law, Dorothy Sweeney, so her local authority, Northamptonshire County Council, would fund her care home costs.
Anyone who has assets of more than £23,250, including property and savings, must pay for their own care.
Police raided Bone's house after a year-long investigation, triggered after they became aware that Sweeney had sold a house shortly before going into a care home.
Bone denied that he was guilty of a fraud charge, saying he had suffered a "personal nightmare at the hands of the police".
He said "we are totally innocent" of the accusation.
Bone has been an MP since 2005, and is known for rebelling against his party in parliamentary votes.
The website They Work For You, which carries information on the voting records of MPs, shows he strongly supported the government's bedroom tax, a housing-linked benefit cut.
This opens the 61-year-old MP up to accusations of hypocrisy.
He also very strongly supported an overall reduction in benefits and voted against increasing benefits by the rate of inflation despite the allegation that he personally profited from our welfare system.
This pattern was in place despite the fact that the UK has the lowest unemployment benefits in western Europe, far below most of our competitor countries.