King, who was 89 when he died in his sleep, had battled diabetes for years, and the disease caused a series of small strokes that took his life, his doctor and a coroner said at the time of his death.
Patty King and Karen Williams, two of King's 15 children, filed two identical affidavits claiming that their father’s personal assistant, Myron Johnson, and business manager, Laverne Toney, gave him medication to induce diabetic shock.
In part, King's daughters claim: "I believe my father was poisoned and that he was administered foreign substances to induce his premature death. … I believe my father was murdered."
Lawyers for King's estate called the claims unfounded and disrespectful.
Nevada's Clark County Coroner said it would investigate with the Las Vegas Police Department's homicide division, adding that the investigation is expected to take at least six to eight weeks.
"At this point, we don't have evidence that these allegations of foul play will be substantiated," Coroner John Fudenberg told BBC News. "However, we are taking them very seriously and will be conducting a thorough investigation."