Melissa Rivers, the daughter of comedian Joan, is preparing to file a medical malpractice and wrongful death lawsuit.

Joan died on September 4, 2014 after suffering ''predictable'' surgical complications while undergoing a minor operation on her vocal cords - and, in response, her daughter has reportedly hired a top US law firm to represent her in a multi-million dollar court battle against the Yorkville Endoscopy Clinic in Manhattan and the doctors who treated her.

A source close to the 46-year-old star told that the suit won't be filed for another month to give her lawyers time to study all of the relevant materials.

What's more, her legal team have contacted people involved in the procedure to tell them not to destroy any documents that relate to the fatal incident.

Meanwhile, a recent statement from the New York City Medical Examiner's Office said Joan's brain was starved of oxygen after she suffered cardiac and respiratory arrest during surgery.