Dirty Money

The plot thickens.

US Representative John F. Tierney’s elderly mother-in-law donated $4,800 to his campaign account at the same time that she was receiving money from a bank account that was allegedly funded with illegal gambling money her son made from an offshore sports betting operation in Antigua.

Tierney’s wife, Patrice Tierney, pleaded guilty in federal court on Wednesday to aiding and abetting the filing of false tax returns for her brother, Robert Eremian, and acknowledged she managed a bank account for him that was allegedly funded with more than $7 million in illegal gambling profits he earned from an Internet sports betting operation based in Antigua.

Prosecutors said Patrice Tierney used the account to pay bills for her 86-year-old mother, Mary, and for Robert Eremian’s three children. Robert Eremian, 57, is a fugitive, wanted on a federal racketeering indictment that was handed down by a federal grand jury in Boston in August.

John Tierney, through a spokeswoman, said today that the contributions to his campaign came directly from Mary Eremian and he never received any money from Robert Eremian’s account.

However, the spokeswoman, Kathryn Prael, said that ‘‘if the campaign finds out any money came from his account, it will return it or contribute it to charity.’’