This juror could wind up on trial herself.

A suspended lawyer with a history of alcoholism and a string of arrests is under investigation by the feds after allegedly lying her way onto a jury that convicted five people in a massive tax-shelter scam.

Court papers unsealed yesterday say Catherine Conrad, 42, hid her checkered past, which also includes being married to a convicted felon she’s described as a “Mafia boss,” during jury selection for a trial in Manhattan federal court earlier this year.

Defense lawyers say the Bronxville woman’s “extraordinary” and, “to our knowledge, unprecedented” deception was uncovered after prosecutors turned over a rambling, postverdict letter in which Conrad said, “I did fight the good fight.”

The July 8 defense filing seeks a new trial for four of the defendants, Paul Daugerdas, Donna Guerin, Denis Fields and David Parse.

Conrad’s convictions include a 1998 guilty plea for drunken driving and a 1999 plea for criminal contempt and aggravated harassment.

In 2009, after her law license was yanked for refusing to cooperate with a professional-misconduct probe, Conrad also pleaded guilty to shoplifting from Westchester supermarkets.

She failed to get back her license last year after a shrink found her “unable to practice law as a result of her alcohol dependency.”

During her 2007 honeymoon in Arizona, Conrad called cops to her motel room at 5 a.m. during a drunken dust-up with her hubby, Frank Rosa, 63, who she said was “a Mafia boss in New York,” court papers say.

Rosa, meanwhile, has his own “extensive criminal history,” which includes a seven-plus-year prison stint in New Jersey, according to the filing.

Conrad’s lawyer, Mark Jay Heller, said, “Ms. Conrad . . . served fairly and impartially, and believes that she has been mischaracterized in the [defendants’ court papers].”

Heller also said that Rosa told him that “he is not now, and has never been, involved in the Mafia.”