Gail Sheridan, the wife of former socialist MSP Tommy Sheridan, has been charged with perjury, her husband said.
The move came after Mrs Sheridan was questioned at Edinburgh's Gayfield police station, where detectives are investigating allegations linked to his high-profile newspaper defamation trial in 2006.
His father-in-law, Angus Healy, has also been charged with perjury, it was confirmed.
Mr Sheridan later told reporters: "Lothian and Borders Police have detained a 71-year-old grandfather for over four hours and charged him with perjury. They've detained a 44-year-old mother-of-one who has never been in trouble in her life for over six hours and charged her with perjury."
The firebrand ex-MSP said his family was "disgusted" about the way they have been treated and claimed they were the victims of a "vendetta".
He said: "We are dismayed and disenchanted by the behaviour of Lothian and Borders Police but we're also determined that we'll fight on to prove our innocence because our family and friends have done nothing to be ashamed of and certainly do not deserve the treatment that we've been subjected to.
"I really do want to raise the question how Lothian and Borders Police can find the time and resources to conduct this vendetta against my family and friends."
The move takes the number of people charged with perjury in connection with the ongoing inquiry to six.
Mr Sheridan, who left the Scottish Socialist Party to set up his own rival party Solidarity, was himself charged with perjury in December, around 16 months after he won his case against the News Of The World.
More recently, three colleagues who backed him in the court action were also charged with perjury - former SSP MSP Rosemary Byrne, Solidarity national secretary Graeme McIver and member Jock Penman.
