CNN reports King's daughters, Patty King and Karen Williams, made the accusations in separate, but identically worded, affidavits filed over the weekend.
"I believe my father was poisoned and that he was administered foreign substances to induce his premature death," they said in their affidavits. "I believe my father was murdered."
King died May 14 in home hospice care in Las Vegas at age 89.
No investigation was conducted at the time of his death. And King's attending physician listed the cause as multi-infarct dementia, which is caused by a series of small strokes.
But the daughter's say that two of King's associates gave him medication to induce diabetic shock.
John Fudenberg, the coroner for Clark County, Nevada, told CNN that initial autopsy results found "no evidence to substantiate the allegations." But full forensic results will take six to eight weeks.