The Westchester County District Attorney's Office confirms it is reviewing one of the most notorious unsolved cases in county history – the disappearance of Kathleen McCormack Durst.

News 12 has learned that the interviews conducted by the DA's office have been going on for the past several weeks and involve at least two investigators and several top attorneys.

The family of Kathie Durst met privately with investigators from the Westchester District Attorney's Office in White Plains last month. Three of her four siblings were there with their spouses.

Durst hasn't been seen since Jan. 31, 1982. She had previously lived in a South Salem home she shared with her real estate heir husband, Robert Durst.

Westchester County District Attorney Mimi Rocah released a statement saying, "The Westchester DA’s Office Cold Case Unit was established to review and reinvestigate unsolved homicides. It is reviewing a number of cases, including the murder of Kathie Durst."

In a news conference Monday, Kathie Durst’s family attorney claimed to have uncovered new evidence that will prove Robert Durst was the one who murdered her nearly four decades ago and alleged that there is an ongoing effort to conceal the truth about the disappearance. Attorney Robert Abrams says Robert Durst’s family has used its power, money and clout to protect him and themselves from criminal prosecution.

Abrams says that one motive for the death was that she was threatening to go to the IRS and others about Robert Durst stealing from the Durst Corporation from the mid-70s to early 80s.

Authorities have revealed a theory Robert Durst might have buried Kathie Durst's body in southern New Jersey. 

In 2003, the eccentric, often cross-dressing Durst was also acquitted for another brutal murder - of a friend in Galveston, Texas, after claiming he acted in self-defense.

And then there was a chilling final statement from Durst in a 2015 HBO documentary - "What the hell did I do? Killed them all, of course."

Robert Durst was back on trial in Los Angeles Monday in the killing of his friend Susan Berman, who was believed to have knowledge about Kathie Durst's disappearance.

His attorneys are asking for a delay due to his health concerns.

In a statement, Jordan Barowitz, a spokesperson for the Durst family, said, “Mr. Abrams is a member of the cottage industry that seeks to personally profit off of Robert’s victims, even if it involves disrupting the prosecution of the murder of Susan Berman. The truth is that the Durst family is appalled by Robert’s actions and has cooperated with authorities to help ensure justice is served. These allegations are false and have been repeatedly debunked.”